Flash hole blow up

[joeb33050]

Some shooters drill out flash holes to 1/8" or #28 drill = .1405 for use with reduced loads to reduce/eliminate shoulder setback. Large primer cases)
Some say to segregate these big-flash-hole cases, that use of them with full loads will blow up the gun.
I'm finding it hard to understand the WHY.
1. Does anyone here have experience with big flash holes and full power loads?
2. I'm trying to get some MA friends to experiment with maybe a 7.7 Jap. Does anyone out there have a low value strong bolt action rifle and interest in maybe blowing it up? In the name of science? We're talking a tire and a string here.

joe brennan

[Bass Ackward]

Some shooters drill out flash holes to 1/8" or #28 drill = .1405 for use with reduced loads to reduce/eliminate shoulder setback. Large primer cases)
Some say to segregate these big-flash-hole cases, that use of them with full loads will blow up the gun.
I'm finding it hard to understand the WHY.
1. Does anyone here have experience with big flash holes and full power loads?
2. I'm trying to get some MA friends to experiment with maybe a 7.7 Jap. Does anyone out there have a low value strong bolt action rifle and interest in maybe blowing it up? In the name of science? We're talking a tire and a string here.

joe brennan


Joe,

I do on #1. A absolute full power? No. Because I got over pressure signs well below max charges. This is using both cast and jacketed.

I used the chronographed velocity and had Quickload predict the pressure which went over 75,000 psi. I did learn from that to drop down in powder speed when straight sided cases lengthened 3/16" on a single firing.

And I have similar high pressure experience with too small of a flash hole in Speer DWM brass from the early 70s in 7MM Mauser. (Before Quickload or I even owned a chronograph)

Both can cause high pressures though for different reasons. What would you like to know?

[joeb33050]

Joe,

I do on #1. A absolute full power? No. Because I got over pressure signs well below max charges. This is using both cast and jacketed.

I used the chronographed velocity and had Quickload predict the pressure which went over 75,000 psi. I did learn from that to drop down in powder speed when straight sided cases lengthened 3/16" on a single firing.

And I have similar high pressure experience with too small of a flash hole in Speer DWM brass from the early 70s in 7MM Mauser. (Before Quickload or I even owned a chronograph)

Both can cause high pressures though for different reasons. What would you like to know?

I don't understand this.
Did you shoot "high" (= up to factory) pressure loads in a rifle with enlarged flash holes in the cases?
If so, please tell me all about it.
Also, tell about the small flash hole experience.
Thanks;
joe brennan

[66gt350]

I drill out my 45LC brass to 9/64", but I these are only blackpowder blanks that I make to keep the primers from backing out and locking up the cylinder.

[mooman76]

I have an old 7mm Spanish Mauser I'm mad at.

[joeb33050]

I drill out my 45LC brass to 9/64", but I these are only blackpowder blanks that I make to keep the primers from backing out and locking up the cylinder.
When I googled on "flash hole oversize" or something like that I found that Winchester made/makes 45 ACP cases with ~.140" flash holes for use with no-lead primers and no-lead bullets. The story is that these can be used for normal reloading, with the big flash holes. I'll go back and try to understand it, but the question revolves around rifles so I didn't pay much attention.
joe brennan

[joeb33050]

I have an old 7mm Spanish Mauser I'm mad at.

If that's a serious offer, you're on. Let us know and we'll write the test protocol.
Thanks;
joe b.

[Larry Gibson]

Some shooters drill out flash holes to 1/8" or #28 drill = .1405 for use with reduced loads to reduce/eliminate shoulder setback. Large primer cases)
Some say to segregate these big-flash-hole cases, that use of them with full loads will blow up the gun.
I'm finding it hard to understand the WHY.
1. Does anyone here have experience with big flash holes and full power loads?
2. I'm trying to get some MA friends to experiment with maybe a 7.7 Jap. Does anyone out there have a low value strong bolt action rifle and interest in maybe blowing it up? In the name of science? We're talking a tire and a string here.

joe brennan


Joe

This might be a case of condeming a technique because of miss application (sorta like the use of dacron wads cuasing ringing). Those of use who drill out the flash holes (I use the #28 drill) do so with light loads of quick burning powder, i'e "squib loads". The reason is to prevent the force of the primer explosion from forcing the case forward and setting the shoulder back. The drilled flash holes also get the flash to the powder much quicker and reduces any "position sensitivity". Flash holes are drilled in rimless cases that headspace on the shoulder.

What do you mean by "full power loads"? Cases with drilled flash holes are meant only for reduced light loads and certainly not for anything approaching what I consider a "full power load", i.e. 180 gr jacketed SP at 2700+ fps in and '06. I have been sneaking up close to regular CAST bullet loads in the .308 with flash hole drilled cases, i.e. a 311291 over 4895. so far I'm up to the 1800 fps range without any signs of pressure problems. ES and SD of all loads with drilled flash holes are consistantly lower than with regular flash holes. I plan on stopping at 2200 fps (if I don't get any pressure signs) with that bullet as accuracy falls off past that with the 1-12" twist barrel I'm using. I am going slow and easy. Even if I succede I won't recommend it as I'm not seeing THAT much benifit and it's to easy to misinterprete it's application.

Larry Gibson

[mooman76]

Sounds like a project! The only thing is It has a chamber vent hole. Don't know if that makes a difference or not!

[Bass Ackward]

I don't understand this.
Did you shoot "high" (= up to factory) pressure loads in a rifle with enlarged flash holes in the cases?
If so, please tell me all about it.
Also, tell about the small flash hole experience.
Thanks;
joe brennan


Joe,

I was shooting 55 grains (full case) of H-4895 with a 300 grain Barnes bullet in a 458X2. This load was used in unaltered cases with Fed 215 primers because it was borderline too slow for the bullet weight. Velocity was around 2300 fps. Same batch of cases that had flash holes opened, raised presure only slightly producing velocity of 2350 fps which established a false sence of security on my part.

Confident, the same cases were used with a 375 grain lead bullet and H-322. While working up a modest load we went to 55 grains and found that velocity exceeded 2200 fps at a predicted 55,000 psi with the standard cases. Accuracy was around 52 grains at 2100 fps. But this time, when cases were inadvertintly charged with 52grains that had large flash holes, velocity jumped to 2450 fps which Quickload estimated took 75,000 psi to produce. Cases were trimmed almost 3/16" on the enlarged flash hole cases, while the standards were quite fine.

Two powders with very close burn rates acted entirely differently as evidently H-322 had crossed over a threshold when using a heavier bullet. Those cases with enlarged flash holes could not be used for powders faster than H-322 without requiring a substancial quantity reduction. heavier bullets were worse than lighter offerings. Even pistol primers produced more velocity with 4198 in enlarged hole cases compared to magnum rifle primers did with the same charge in standard cases.

A similar pressure event happened with smaller holes than standard which cused poor ignition.

Back in the early 70s, Speer sold brass marketed under the Speer DWM brand. I believe that this excellent brass was made in Germany. Two previous boxes turned out to be very uniform compared to brass of this day, and the anneal was first rate. The third box purchased later apparently had flash holes that were too small. Certainly smaler than the prior purchases.

This caused erratic ignition with the same load successfully developed and used in the previous cases. Some loads produced very modest recoil and others flattened primers leaving visible extractor marks on the brass and swollen bases. Cases that were subjected to the higher pressue levels required extensive trimming and were retired after only one loading. Don't have the load anymore, but it was a mid range offering obtained from a reliable reloading manual at that time. The cartridge was a 7X57 using a 130 grain Speer. I belive the powder was 4320. After diagnosing the problem, the holes were opened the same as the prior brass, and the survivors lived a respectable reloading life.

Moral of the story is to always start low and work up any time you change any variable.

[Ricochet]

I expect the big flash holes are just another variable that you need to work up the load with, not just drop it in with a load already worked up.

As for the small flash holes, poor ignition and pressure signs, some 10 years ago I cooked up a hypothesis that perhaps some "SEE" events occurred due to poor ignition partially igniting some of the powder, which burned slowly without immediately igniting the rest of the charge. The slow flame heated the unignited powder deep inside the grain, so that when it did ignite it burned much faster than normal and caused the pressure excursion. I'd expect a noticeable hangfire with that sequence of events, and with a hangfire I'd worry about possible pressure surges.

[joeb33050]

Sounds like a project! The only thing is It has a chamber vent hole. Don't know if that makes a difference or not!

What is a chamber vent hole? It's not a hole from the chamber, where the case is, to the outside, is it?
Thanks;
joe brennan

[joeb33050]

This is nothing to do with condemning a technique; it may have to do with the warnings we attach to the use of cases with drilled flash holes and techniques we use to assure that they aren't used with full loads.

I'm told that using a full power jacketed load in a case with flash hole drilled out to 1/8" will cause the gun to blow up.
Hence the reason to segregate cases.
I find it difficult to believe that the gun will blow up
I think that 1. the pressure inside the primer cup = the chamber pressure regardless of the size of the flash hole and 2. the primer cup is supported by the bolt head and won't fail = leak at any in-spec pressure.
I don't know.

I think that the theory is that;
the big flash hole lets more gas into the primer pocket
the gas/pressure causes the primer cup to fail, get a hole in it
the gas whistles through, eating away the case web until the case base fails
the gun blows up

Now, if this is true, we should certainly segregate cases and not use the big-flash-hole cases in any other loads; and maybe even stronger measures are called for.

If it isn't true, we should still segregate cases, but maybe the stronger measures aren't called for.

There's no "working up the load" called for, we/I don't want to know WHERE in the powder charge spectrum the failure occurs.

We/I want to know this: If a set of big-flash-hole cases are loaded to a full load in a rifle (bolt action, Mauser-type, strong) and fired (tire and string), then do they blow the gun up?

joe brennan






Joe

This might be a case of condeming a technique because of miss application (sorta like the use of dacron wads cuasing ringing). Those of use who drill out the flash holes (I use the #28 drill) do so with light loads of quick burning powder, i'e "squib loads". The reason is to prevent the force of the primer explosion from forcing the case forward and setting the shoulder back. The drilled flash holes also get the flash to the powder much quicker and reduces any "position sensitivity". Flash holes are drilled in rimless cases that headspace on the shoulder.

What do you mean by "full power loads"? Cases with drilled flash holes are meant only for reduced light loads and certainly not for anything approaching what I consider a "full power load", i.e. 180 gr jacketed SP at 2700+ fps in and '06. I have been sneaking up close to regular CAST bullet loads in the .308 with flash hole drilled cases, i.e. a 311291 over 4895. so far I'm up to the 1800 fps range without any signs of pressure problems. ES and SD of all loads with drilled flash holes are consistantly lower than with regular flash holes. I plan on stopping at 2200 fps (if I don't get any pressure signs) with that bullet as accuracy falls off past that with the 1-12" twist barrel I'm using. I am going slow and easy. Even if I succede I won't recommend it as I'm not seeing THAT much benifit and it's to easy to misinterprete it's application.

Larry Gibson

[Bass Ackward]

Joe,

Drilling out a flash hole depends on how big you drill it and the conditions you use in the case. It amounts to no more than using a hotter grade of primer. BUT it is more sensitive as bullet weight within a caliber increases and powder speed picks up. If your sytle of reloading is to use full cases of powder that never reach a SAAMI max for that particular cartridge, you may never see the difference.

I had a 7MM Remington Mag that would not shoot anything faster than 4064 powder with a 145 bullet no matter what I did. Had those cases been drilled out, I couldn't have used that fast of a powder in that big of a case. Had the gun worked with RL@@ on down in burn rate, I might have been the happiest guy in the world.

And you can pierce primers in the space between the firingpin and the bolt head itself. I did at 75.000 psi.

[Ricochet]

It amounts to no more than using a hotter grade of primer.

Exactly.

[porkchop bob]

When I googled on "flash hole oversize" or something like that I found that Winchester made/makes 45 ACP cases with ~.140" flash holes for use with no-lead primers and no-lead bullets. The story is that these can be used for normal reloading, with the big flash holes. I'll go back and try to understand it, but the question revolves around rifles so I didn't pay much attention.
joe brennan

I have picked up several of the Winchester lead-free 45ACP brass from the indoor range I use. Their flash hole is larger. I have read that the lead-free primer was not as strong and the larger flash hole helped. I have them sorted and sit aside. Not enought on hand to mess with.

Today, I went to Dogpile and searched "Winchester lead-free primers". Several results. You may want to read this one.

http://www.findarticles.com/p/articles/mi_m0BQY/is_5_51/ai_n13469620

Once fired brass that are pick ups from the range should be checked carefully before being processed and reloaded. Read the above article. What we have long considered and used as 'standards' are no longer standard.
You may find, for example -
_ 45ACP with wide flash hole
_ 45ACP with small primer
_ 45ACP with heavy crimped primer

Bob

[Ricochet]

It's long been known among interior ballisticians that the blast of the primer firing can shatter powder grains near the flash hole. I expect that enlarging the flash hole increases the brisance (shattering effect) of the primer explosion. As powder grains are broken into smaller fragments, they burn faster. This has an effect much like a duplex charge with a small amount of faster burning powder down around the flash hole. Different powders break more or less easily, position of the powder against or away from the flash hole would affect it, and I expect that the very fast powders would be less affected by it than slower ones.

Old smokeless powder becomes more brittle, while losing very little energy from denitration, and powder shattering when the primer fires generally causes old ammo to rise in pressure. That's a reason that a lot of older military ammo has been surplused out, because it no longer meets maximum pressure standards. May well explain why the older Turkish 8mm is often very "hot."

[joeb33050]

Joe,

Drilling out a flash hole depends on how big you drill it and the conditions you use in the case. It amounts to no more than using a hotter grade of primer. BUT it is more sensitive as bullet weight within a caliber increases and powder speed picks up. If your sytle of reloading is to use full cases of powder that never reach a SAAMI max for that particular cartridge, you may never see the difference.

I had a 7MM Remington Mag that would not shoot anything faster than 4064 powder with a 145 bullet no matter what I did. Had those cases been drilled out, I couldn't have used that fast of a powder in that big of a case. Had the gun worked with RL@@ on down in burn rate, I might have been the happiest guy in the world.

And you can pierce primers in the space between the firingpin and the bolt head itself. I did at 75.000 psi.

I'm still looking for somebody with a strong bolt action rifle who's willing to perform the experiment. I've got two guys in MA interested, working on a 7.7 Jap rifle.
Bass; if I understand, you're saying that an enlarged flash hole gives bigger pressures and higher velocities than the in-spec flash hole.
I plan to experiment along these lines, starting with cast bullets in a 30/30 and a 30/06.
I'll keep us all informed.
joe b.

[Bass Ackward]

Bass; if I understand, you're saying that an enlarged flash hole gives bigger pressures and higher velocities than the in-spec flash hole.
joe b.


Joe,

I say that it matters on the case design, the size hole you drill, the bullet weight, and the powder speed. Results comes on three situations or levels.

1. That means that in some situations, with light bullets and real slow powders, you might not notice any difference what so ever, and falsely think enlargeing makes no difference.

2. Speed the powder up and or increase bullet weight and you might be in a zone where you see quicker pressure but to the same expected level where your results seem .... just .... like you would expect from a hotter primer. This too may falsely encourage you to continue.

Both of those senarios are manageable. The danger comes in the third situation. The third situation is NOT PREDICTIBLE!!!!!!!!!!!!!

3. Here, a seemingly safe and still slow powder speed crosses a burn rate threshold where the increased pressure goes straight up. You may see an increase in velocity or as in my case, you may NOT!!!!!! If you survive this point and misdiagnose the problem, you may want to increase the powder charge again which I did by one grain. This caused my cases to stretch almost 3/16" on a straight sided case!!!!!!!!!!!!!

Here is an expample:

You have experience with an 06. Lets say you try a 150 grain jacketed. Let's say you try 4895. At 47 grains you get 2800 fps. You add 1 more grain to 49 grains which is max and you get 2900 fps. Roughly 100 fps for the grain. You add one more grain to 50. Now you only get a 40 fps gain. You add one more grain to 51 and you get flatened primers, enlarged case heads, and basically the same velocity.

Using enlarged flash holes is like going from 47 grains to 51 grains in 1 (that's ONE) step. You can be fine, and without warning, you are way over the limt. That is the danger you face if you enlarge the holes. And depending on how large you enlarge them, will change that critical point.

Is that clear now?

[Ricochet]

Right, it's unpredictable as substituting a magnum primer for a standard one in a worked up maximum load is. Start with a sane reduced load and work it up, and you can be safe with it IMO.

[mooman76]

Joeb
I thought I answered you but guess not. The chamber vent hole I have only seen a few times in older rifles like late 1800's early 1900's. Mine is a spanish mauser 7x57 of some type from that era. The vent hole is in the chamber or right behind I guess. You can't see the brass case but you can see the front part of the bolt. The hole is figure 8 shaped like the drilled 2 holes together. I was told it was to vent excess pressure rather than blow up the gun. I assume sence you rarely see this and never on a modern rifle, it didn't work or at least didn't always work as intended!
I do have a 7.7 jap but and it is the late production no frills but it has a perfect cusantiminium ( I can't spell the flower)so I'm not willing to blow it up! But this spanish mauser is a piece of C$@p. Let me know what you want to do!

[Bass Ackward]

Right, it's unpredictable as substituting a magnum primer for a standard one in a worked up maximum load is. Start with a sane reduced load and work it up, and you can be safe with it IMO.


Ric,

I dropped 3 full grains which should have been like 45,000 psi and certainly safe enough to substitute a magnum primer in that situation. That's how slow the powder was for that application. And since "all" cases stretched 3/16 " on a single firing, I doubt that any magnum primer change would do that. And realize that 52 grains is to the bottom of the bullet. No SEE, no filler. Nothing else to blame it on.

That is my point. I understand exactly how you feel. I know because I would have bet my place in heaven on situation 2. But .... I found situation 3.

So at least consider the possibility, there is bend in the road ahead and maybe you will recognize it when you come to it.

[Ricochet]

Hmmm. Hard to see how the flash hole size alone could make such a big difference. I'd love to see some pressure test data!

[joeb33050]

Joeb
I thought I answered you but guess not. The chamber vent hole I have only seen a few times in older rifles like late 1800's early 1900's. Mine is a spanish mauser 7x57 of some type from that era. The vent hole is in the chamber or right behind I guess. You can't see the brass case but you can see the front part of the bolt. The hole is figure 8 shaped like the drilled 2 holes together. I was told it was to vent excess pressure rather than blow up the gun. I assume sence you rarely see this and never on a modern rifle, it didn't work or at least didn't always work as intended!
I do have a 7.7 jap but and it is the late production no frills but it has a perfect cusantiminium ( I can't spell the flower)so I'm not willing to blow it up! But this spanish mauser is a piece of C$@p. Let me know what you want to do!

Now I think I understand about the vent hole.
Here's what I think the experiment should look like:
Take 5 once-fired cartridge cases and drill the flash holes out with a 1/8" drill.
Load these with a full power safe (max) load. In the Lyman 48th there are a number of 45,000 CUP loads, none much higher.
Get a tire and a string.
Shoot them and see what happens.
Pictures would be great.
If the gun doesn't blow up or do anything bad, repeat with 5 cases with the flash holes drilled with a #28 drill, .140"

I don't see any point to working up to it, we want to know if the gun blows up with full power loads.

Anybody else chime in about the experiment protocol.
I wish I could be there!!
joe b.

[trk]

If the cards are played right, the gun could (afterwards) be a candiate for the next gun-by-back campaign by the anti-gun folks.

[joeb33050]

Now I think I understand about the vent hole.
Here's what I think the experiment should look like:
Take 5 once-fired cartridge cases and drill the flash holes out with a 1/8" drill.
Load these with a full power safe (max) load. In the Lyman 48th there are a number of 45,000 CUP loads, none much higher.
Get a tire and a string.
Shoot them and see what happens.
Pictures would be great.
If the gun doesn't blow up or do anything bad, repeat with 5 cases with the flash holes drilled with a #28 drill, .140"

I don't see any point to working up to it, we want to know if the gun blows up with full power loads.

Anybody else chime in about the experiment protocol.
I wish I could be there!!
joe b.

And PLEASE, mooman76, write everything down the day and date and load and where and everything. And PLEASE, be careful.
Thanks;
joe b.

[porkchop bob]

IMO, the results will be a wasted rifle and mis-leading results. Two stated variables - vent hole and drilled out primer hole. Will a newbe read the posting and conclude anything less will be safe in his or her rifle? How many times will the test be repeated to rule out the posibility the first rifle was not stronger than usual? What assurances will any of us have our rifle is as strong?
Bob

[Char-Gar]

The only way, at least in my mind, to settle the issue is to have a lab do the test in a pressure gun. How much could it cost to have 15 rounds put through a pressure gun?

[Ricochet]

That would be the only useful data, from measuring pressures with normal and enlarged flash holes. And I'll bet it's been done, if we could find it.

[joeb33050]

This is all about safety, and advice to shooters.
If you don't understand what it's about and why, please read the thread-I think it's pretty clear. If that doesnt clarify the matter, ask and I'll give it a shot.
If you have questions or criticisms or suggestions about the test protocol, please write them here.
We're not interested in measuring anything here, we're/I'm interested in testing the ?hypothesis?: If you shoot a 30/06 at 50,000 pounds pressure with a case with a flash hole enlarged to 1/8", then the gun will blow up."
If the 7MM mauser blows up, we have evidence that the hypothesis is correct.
If it doesn't bl;ow up, we have some evidence that the hypothesis is incorrect.
In neither case is the evidence 100% PROOF-
Ricochet, chargar and porkchop bob-your opinions are always welcome; please make sure to comment after the test, no matter the outcome.
Thanks;
joe b.

[Larry Gibson]

joe b

So then to clarify with the flash hole drilled cases; are you loading (going to test) the 7mm Mauser to normal cast bullet velocity for this cartridge, i.e. a 160-175 gr cast bullet over a medium burning rate powder to 1800-1900 fps? Or are you loading the 7mm Mauser to factory (European) pressures with 139 - 175 gr jacketed bullets to 2800 to 2400 fps respectively?

I ask because I have already snuck up to 2044 fps with the 123 SKS/AK bullets the '06 over 18 gr Unique with well fire formed cases and the flash hole drilled with a #28. Those loads do not exhibit any signs of excessive pressure being applied to the primer. I have shot several hundred of them so far. I also have been working with the .308 with flash holes drilled and 311291 over 4895. I'm up around 1800 fps and again no sign of excessive pressure on the primer.

Larry Gibson

[porkchop bob]

Joe B.
I have read this thread a few times. I will comment, try to summarize and ask questions.

I agree the pressure on both sides of the primer hole is the same.

Now let’s talk about force. Increasing the size of the flash hole will increase the force exerted on the primer side of the flash hole. Assuming the bolt face is even and snug against the primer, the weak point will be the dimple from the strike of the firing pin.

Hopefully, the firing pin, in the test rifle, fully retracts behind the face of the bolt after striking the primer. The test results should make a note of this.

Paint the bold lugs with machine blue and see how tight and evenly they fit when the bolt is closed. Measure them again after the tests, if it is possible.
_ If not tight, the bolt will set back and the brass will flow at the base.
_ If not even, the bolt will cant to one side and the brass will be distorted and flow more so towards that side.

There is only one test rifle.
_ The variable will be a set of rounds loaded in brass having an enlarged primer hole. As I understand it, a load designed to blow the rifle up.

_ Missing is a similar set of rounds loaded in brass having a normal primer hole.

Assuming the rifle does not blow up with the normal set of test rounds, then I would be interested in knowing it did when the enlarged set was fired. I would be more interested in knowing how the case failed.
_ Was it at the primer?
_ Was it at the base of the brass?
_ If not a brass failure, what caused the rifle to blow up?

Joe B., I look forward to the test, published results and findings.

Thanks, Bob

[Ricochet]

I agree the pressure on both sides of the primer hole is the same.

Now let’s talk about force. Increasing the size of the flash hole will increase the force exerted on the primer side of the flash hole.

No, it won't. If the pressure is the same on both sides of the flash hole, so is the force against the primer cup. Force = pressure x area.

The only way this can make a difference is by affecting the pressure developed in the powder chamber, by affecting the ignition of the powder.

The main way I think increasing the size of the flash hole may increase pressure is by letting more of a shock wave from the primer explosion through into the powder, shattering grains into small, uncoated fragments that burn faster. A small flash hole "throttles" the flow of gas from the explosion in the primer pocket, so it's less of a shock mechanically to the powder grains.

Remember, lead styphnate and tetracene are high explosives, as is PETN, which is a major ingredient in some primers. (As also is the diazodinitrophenol found in no-lead primers.) Primers go off with a pretty sharp blast.

[joeb33050]

joe b

So then to clarify with the flash hole drilled cases; are you loading (going to test) the 7mm Mauser to normal cast bullet velocity for this cartridge, i.e. a 160-175 gr cast bullet over a medium burning rate powder to 1800-1900 fps? Or are you loading the 7mm Mauser to factory (European) pressures with 139 - 175 gr jacketed bullets to 2800 to 2400 fps respectively?

I ask because I have already snuck up to 2044 fps with the 123 SKS/AK bullets the '06 over 18 gr Unique with well fire formed cases and the flash hole drilled with a #28. Those loads do not exhibit any signs of excessive pressure being applied to the primer. I have shot several hundred of them so far. I also have been working with the .308 with flash holes drilled and 311291 over 4895. I'm up around 1800 fps and again no sign of excessive pressure on the primer.

Larry Gibson

Larry;
The object is to test a load that produces pressure in the 45,000 pound range as given in the Lyman or other handbook. This is the "full load", max in my manuals-maybe because of the Rolling Blocks?? or earlier Mausers?
I am interested in both of your loads, precisely described, and the guns used. I'd like to know the "Quickload" pressure estimates fot them. If you'll post them, maybe we can find a Quickload owner to run the pressure.
I'd also like to get Bass's load, precisely, for Quickload pressure estimation.

[joeb33050]

Joe B.
I have read this thread a few times. I will comment, try to summarize and ask questions.

I agree the pressure on both sides of the primer hole is the same.
(I don't know what this means.)

Now let’s talk about force. Increasing the size of the flash hole will increase the force exerted on the primer side of the flash hole.
( I don't know that this is true, and suggest that it is not. The primer goes off, blowing flame through an ,080" flash hole. There's some pressure inside the primer/primer pocket cylindrical space with the only opening the flash hole. I don't know what the pressure is, but I do know that the pressure is enough to generate a force that moves the shoulder back on a 30/06 empty case. Now the powder lights up, certainly a continuous thing going on, primer-powder-bullet moves... The pressure builds in the case to ??above ?? the pressure of the primer. ??The gas goes through the .080" flash hole increasing the pressure in the primer slash to ?? but you're suggesting less than full pressure, before the pressure goes down. In my mind I don't see a lot of gas needed going through the flash hole to pressurize the primer pocket. A large primer pocket is .210" diameter X .132" deep with a volume of .0046 cubic inches less the primer and anvil volumes. The ratio of .080" flash hole area to primer pocket volume is ~1:1, 1 square inch to 1 cubic inch, one square foot to one cubic foot. I think about a cubic foot box with one side open and 50,000 psi on the open side, and I see the box fill quick. But, I don't know. I'm thinking that the flash hole, .080" or .125" or .140" is large enough to allow pressure to maximize in the pocket. But I don't know. I don't think that a larger flash hole will increase pressure. BUT, I can see that if the primer fails, then a larger flash hole MAY?? allow more gas to escape, maybe."

Assuming the bolt face is even and snug against the primer, the weak point will be the dimple from the strike of the firing pin.
( I don't know this. If the brass primer cup dimple doesn't flatten back out or extrude into the firing pin hole, and mine don't-this I always took as a sign of excess pressure or bad firing pin/hole geometry- and if the pressure isn't greater in the primer pocket with a big flash hole, then I don't know what's going to fail. I don't know.)
,
Hopefully, the firing pin, in the test rifle, fully retracts behind the face of the bolt after striking the primer. The test results should make a note of this.

Paint the bold lugs with machine blue and see how tight and evenly they fit when the bolt is closed. Measure them again after the tests, if it is possible.
_ If not tight, the bolt will set back and the brass will flow at the base.
_ If not even, the bolt will cant to one side and the brass will be distorted and flow more so towards that side.

There is only one test rifle.
_ The variable will be a set of rounds loaded in brass having an enlarged primer hole. As I understand it, a load designed to blow the rifle up.

_ Missing is a similar set of rounds loaded in brass having a normal primer hole.
( YES, we need to shoot the gun with ~5 rounds and a normal flash hole to make sure it doesn't blow up. MOOMAN, will you add this as the first step?? Thanks!!!!)

Assuming the rifle does not blow up with the normal set of test rounds, then I would be interested in knowing it did when the enlarged set was fired. I would be more interested in knowing how the case failed.
_ Was it at the primer?
_ Was it at the base of the brass?
_ If not a brass failure, what caused the rifle to blow up?

Joe B., I look forward to the test, published results and findings.

Thanks, Bob

Thanks, I needed that!
joe b.

[porkchop bob]

Good evening, Joe B. A Merry Christmas Eve it is.

To address some of the questions you raise.

Think of a long thin balloon and then squeeze it with you hand until you have two sections: a small one and a much larger one. The pressure in both sections will be the same. Picture now a cartridge with the primer pocket/primer being the small section and the larger section being what we think of the inside/volume of the cartridge. Because they are connected by the primer hole, the pressure on both sides will be equal. For an instant, an in-balance can exist, but the pressure will become equal very quickly.

Simple hydraulics says a piston of 2 inches diameter connected to another piston of 6 inches in diameter can multiple the force applied by the smaller piston upon the larger one by a factor of 9. Push the small piston down 9 inches with a one pound weight and the larger one will rise 1 inch with a nine pound weight. (6 is 3 times larger than 2. 3 squared is 9)

In the case of the cartridge and the primer pocket/primer, reverse the situation. Increasing the diameter of the primer hole will result in more force being applied outward pushing the inside of the primer towards the face of the bolt.

There are several engineers on the board. I trust they will comment one way or another on the validity of this simplistic explanation.

Bob

[leftiye]

You're goin' ta have some trouble with primers that won't fire if ya bore out the flash hole until the anvil isn't sittin' on somethin'. Also, though the ignition should be speeded up, there will be a definite place where a larger hole has no further effect.

[Linstrum]

And then to complicate things there are Berdan primers with TWO flash holes! Yeah, I know the holes in Berdan pockets are smaller, but the flame front is initiated in two places.

[Ricochet]

Bob, none of that fancy hydraulic piston stuff applies to this case. What you've got is a pressure in a chamber, and an area of the primer cup that it works against. There's your force. If increasing the flash hole size increases it, it has to be by increasing the pressure in the powder chamber, which connects to the primer pocket. That would have to be by affecting the ignition.

[porkchop bob]

Bob, none of that fancy hydraulic piston stuff applies to this case. . . .
Thanks. This forum is full of lessons to be learned. Bob

[Ricochet]

Isn't that the truth?!

[monadnock#5]

Let me start off by saying that I'm way out of my depth on this subject. No degree, and no wealth of experience. That said, it is my recollection that the US Navy dropped a lot of bags of blackpowder onto the tarmac from a crane before they got a result that said "Yes, the explosion on the Iowa could have been caused by the loader ramming the charge into the gun with the same gusto that the projectiles are inserted". If the object of this exercise is to come to a definite conclusion as to whether enlarged flash holes create a dangerous condition, we need to fire a lot more than five rounds IMHO.

Ken

[joeb33050]

Let me start off by saying that I'm way out of my depth on this subject. No degree, and no wealth of experience. That said, it is my recollection that the US Navy dropped a lot of bags of blackpowder onto the tarmac from a crane before they got a result that said "Yes, the explosion on the Iowa could have been caused by the loader ramming the charge into the gun with the same gusto that the projectiles are inserted". If the object of this exercise is to come to a definite conclusion as to whether enlarged flash holes create a dangerous condition, we need to fire a lot more than five rounds IMHO.

Ken

If the gun blows up on the first shot, second,...fifth-don't we know something?
If the gun doesn't blow up?
There are a number of possible outcomes, each of which has at least one precisely true statement attached.
What do you define the question as?
joe brennan

[trk]

OK, I looked it up in MY Funk and Wagnalls:

Let me quote from Philip B. Sharp’s reference Complete Guide to Handloading beginning on page 35:

Actual tests show that reaming out flash holes to a larger size will slightly increase velocity and greatly increase pressure! Furthermore there will be a tendency toward primer leakage and the stretching of pockets with normal pressure loads. To verify these findings, the author asked the Hercules Experiment Station to try reaming flash holes oversize and report findings. The .270 Winchester cartridge was chosen for the experiment, non-corrosive priming, 130 grain bullet, and a full charge of HiVel #2. Normal flash-hole size in 0.80 inch, and this was tried, the loading being repeated with the vent reamed to .101.

With the normal flash hole, the maximum velocity for the series of twenty shots ran 3067 f.s. instrumental, with 2984 f.s. minimum. Average or mean velocity was 3036 f.s. Pressure tests for the twenty shots showed 56,600 pounds maximum, 50,400 for minimum and 54,600 for the mean or average. Using the same components, the flash hole was reamed to .101 and the test repeated. Maximum velocity jumped to 3138 f.s. instrumental, minimum was 3066 f.s. while the average was 3105, and average increase of 69 f.s. The real problem occurred with the pressures. Maximum jumped to 68,800 pounds, minimum was 58,000 pounds, while the mean ran 63,600, and increase of 9000 pounds with a velocity increase of only 69 f.s. These figures should be self-explanatory. Don’t ream out your flash holes to larger than normal size. Such reaming as is necessary should be solely for the purpose of removing burrs.

This 3rd edition 2nd revision is copyrighted 1937, 1941, 1949, 1952 and 1953 published by Funk and Wagnalls Company, New York.

[felix]

HiVel #2 was one of the hottest powders in existance then, and was about equal to a typical Cordite cooler lot. 40 percent nitroglycerin. Pressures prolly won't come close to the Hivel percentage gain when using the same experiment but using 4350/4831 instead. Just my bet. However, using Hivel with condoms will break in the throat on a new barrel quite rapidly. So, it does have some current use. ... felix

[Ricochet]

Thanks for reporting that!

I felt certain someone would have investigated that, and I'll bet there's more tested data out there...

[trk]

I find it intersting that he went from .080 to .101 and got the results he did. AND wasn't Ed Harris that predicted catestrophic failure at .125"? There are MANY other pages worth of stuff by Sharp - well worth the read.

As an engineer I KNOW that if I come up with an idea that there are MANY folks that have thought of it before and tested it - just a matter of digging a little to find what results they got.

[joeb33050]

Well, I hope that the test shows the truth. Perhaps the modern/other powders won't show this increase in pressure, and the gun won't blow up.
Both SAAMI and the reloading equipment manufacturer's association (I wonder if the apostrophe goes in manufacturer's) warn against increasing the size of flash holes because of the attendant pressure rise.
Testing tells.
joe brennan

[Ricochet]

Yes, it does.

The effect is likely to be different with different loads.

[Char-Gar]

Yes, I read that in Phil Sharpes book, but it was some time ago. I think I still have a can or two of HiVel #2 around, but quite using it when it became evident that it did eat barrels at a faster rate.

For all of that and all of that.. 64K CUP won't take a good action apart. Mind you I said good action. This would exclude Krags and low numbered 03 and some others.

At 64K you are going to get enlarged primer pockets, case head flow into depressions in the bolt head, hard extraction etc, but that will be all.

I certainly don't think 64K is anything we want to shoot, but it won't cause catastrophic failure in a good rifle action. Probably would not cause any damage at all.

The point being, the rifle tied to a tire and pull by the string wouln't blow up and might not give any reliable information other than high pressure signs.

[joeb33050]

I'm starting to think that we're missing the boat here. There are loads of opinions about whether the gun will blow up or not. How about a pool, all the opinion holders throw in $5 and the winners divide the cash? I'll hold the money!
joe brennan

[trk]

I think it's academic on whether or not a given gun blows up. It simply means that some unknown pressure limit was exceded. From Sharp's reference and others' I'm content to keep the flash holes standard.

[Char-Gar]

Joe... What do you mean by "missed the boat"? I thought the discussion was whether or not enlarged flash holes would cause excessive pressure with standard condom full snort loads. You suggested testing in a low value strong bolt gun via the tire and string method.

If such a test was done, what would be learned? It could show the drilled flash holes produced high pressure than those without drilled flash holes. But without lab equipment it would not show how much pressure increase was generated.

Sharpe's tests indicate this would be the result. High pressure, but not past the red line of brass and rifle strength.

If the rifle flew into pieces, that would prove the pressures were high enough to destroy the rifle, but would still not give a real pressure reading.

If we want to get a money pool going, I would suggest it be spent on pressure testing by H.P. White. Then we would have made some kind of contribution other than several pages of opinions and banter.

[joeb33050]

Joe... What do you mean by "missed the boat"? I thought the discussion was whether or not enlarged flash holes would cause excessive pressure with standard condom full snort loads. You suggested testing in a low value strong bolt gun via the tire and string method.

.

No, it's about whether or not shooting a "full" load with a case with an enlarged flash hole will blow the gun up. That's what I want to know.
joe brennan

[Ricochet]

Well, I don't think one test of a rifle in a tire fired by a string will give us any generalizable conclusions. I'll save my $5 toward my next bottle of White Lightning.

[Bass Ackward]

No, it's about whether or not shooting a "full" load with a case with an enlarged flash hole will blow the gun up. That's what I want to know.
joe brennan


Joeb,

In trk's example, they were only opened to .101 which was considered a no no. Now imagine .125.

I suspect that how large tyhe flash hole is opened might be a factor. And case design another.

[Char-Gar]

No, it's about whether or not shooting a "full" load with a case with an enlarged flash hole will blow the gun up. That's what I want to know.
joe brennan

Jeeze Joe... We must be having some sort of time warp communication problem, because we are saying the same things with different words.

[joeb33050]

Pressure is problematical. "Quickload" estimates pressure and velocity without regard to the primer type. Velociy and pressure are not related as I once thought.
Everythin I've read about it tells me that increased flash hole diameter increases pressure, nothing I've read tells me that that increase is enough to blow up the rifle.
trk quotes a 9 ksi average pressure increase with enlarged flash holes.
Here's a reference showing a 12.8 ksi pressure increase caused just by changing primer type. And I don't think the gun blew up.
Handloader, August 2005, "Velocity and Pressure" by John Barsness.
The author cites "Any Shot You Want", the A-Square loading manual concerning variations in pressure with changes in primer. From that manual, on pg. 65 the table "Primer Experiment" shows: 7MM Remington Magnum, 160 grain Sierra boat-tail, 66.0 grains of Hodgdon H-4831 and Winchester cases.
CCI 200 (standard) 3011 fps, 54,800 psi
Rem 9 1/2 M (magnum) 3041 fps, 59,300 psi
CCI 250 (magnum) 3039 fps, 61,500 psi
Fed 215 (magnum) 3036 fps, 61,400 psi
Win WLR (standard) 3024 fps, 64,400 psi
Win WLRM (magnum) 3045 fps, 67,600 psi

The author then performed a test on a ".300 Winchester Magnum with a 23-inch barrel, the load a 180-grain Nosler Partition with 75.0 grains of Hodgdon H-4831 in Winchester cases."
Fed 215M, 2924 fps, 63,800 psi
CCI BR2, 2920 fps, 55,800 psi
Win WLRM, 2991 fps, 70,100 psi

It is clear that pressure varies greatly with primer, while velocity varies much less.

So, pressure varies by flash hole diameter, and even more by change in primer type/brand/whatever it is.




OK, I looked it up in MY Funk and Wagnalls:

Let me quote from Philip B. Sharp’s reference Complete Guide to Handloading beginning on page 35:

Actual tests show that reaming out flash holes to a larger size will slightly increase velocity and greatly increase pressure! Furthermore there will be a tendency toward primer leakage and the stretching of pockets with normal pressure loads. To verify these findings, the author asked the Hercules Experiment Station to try reaming flash holes oversize and report findings. The .270 Winchester cartridge was chosen for the experiment, non-corrosive priming, 130 grain bullet, and a full charge of HiVel #2. Normal flash-hole size in 0.80 inch, and this was tried, the loading being repeated with the vent reamed to .101.

With the normal flash hole, the maximum velocity for the series of twenty shots ran 3067 f.s. instrumental, with 2984 f.s. minimum. Average or mean velocity was 3036 f.s. Pressure tests for the twenty shots showed 56,600 pounds maximum, 50,400 for minimum and 54,600 for the mean or average. Using the same components, the flash hole was reamed to .101 and the test repeated. Maximum velocity jumped to 3138 f.s. instrumental, minimum was 3066 f.s. while the average was 3105, and average increase of 69 f.s. The real problem occurred with the pressures. Maximum jumped to 68,800 pounds, minimum was 58,000 pounds, while the mean ran 63,600, and increase of 9000 pounds with a velocity increase of only 69 f.s. These figures should be self-explanatory. Don’t ream out your flash holes to larger than normal size. Such reaming as is necessary should be solely for the purpose of removing burrs.

This 3rd edition 2nd revision is copyrighted 1937, 1941, 1949, 1952 and 1953 published by Funk and Wagnalls Company, New York.

[joeb33050]

Joeb,

In trk's example, they were only opened to .101 which was considered a no no. Now imagine .125.

I suspect that how large tyhe flash hole is opened might be a factor. And case design another.

I don't know how pressure rises as flash hole diameter increases. It could be a straight line relationship, I suspect an increase for a while then a leveling off.
Note: many responders mentioned the popular #28 drill for opening up flash holes with reduced cast loads, that's .140" I think.
I wonder why we settled on ~.080", when we seem to get a "free" pressure boost from larger flash holes.
I anxiously await the test.
joe brennan

[trk]

"I wonder why we settled on ~.080", when we seem to get a "free" pressure boost from larger flash holes."

Continuing in Philip B. Sharpe's volume, from where I left off,

Just what should the flash-hole size be? A check made early in 1937 with the various ammunition manufacturere indicates that Western Cartridge Company has standardized on the diameter of 0.0815 inch in all calibers, regardless of primer size. Winchester, on the other hand, uses, generally speaking, .070 for all revolver and pistol sizes, including small rifle sizes, a diameter of .080 for all military rifles and general sporting rifle sizes with a single exception of the .220 Swift which runs .060. Bear this in mind with the .220 Swift. The small size flash-hole is of extreme importance; excessive primer pressures are recorded where the large hole is used, and in many cases the primer drops out entirely, spilling gas back through the action. Ammunition made by Remington and Peters is standardized at .060 for all pistol and revolver sizes .070 for all small-sized rifle items ... and .080 for all military-rifle sizes. Frankford Arsenal measures .078 to .082 in both the .30/06 and .45 automatic. Reloaders must bear in mind that these flash-hole sizes have been scientifically developed after considerable research and are the proper diameters for the particular make of primer originally used in the shell. To experiment with different primers, including those of a "stronger" nature, is inclined to build pressures rapidly, not only from the breech-pressure standpoint, but from the primer-pressure angle. This will cause the primer to flow back more or less, making the gun rather difficult to function, or what is even worse, may cause serious leakage or even blown-out primers. Very definate experiments have been conducted to verify this information.

That was written in 1937. Obviously there has been great standardization since then. This may not be the answer to your question, but it is a snap-shot of what was at that particular moment of time. I suspect timing (1937- WWII) had a LOT to do with standardization - as it did in all the rest of the standardization of manufacturing processes.

[mooman76]

JoeB

I am ready to get started on the project. Would have done it sooner but with the hoildays and had the flu this past week, I didn't have the time! I never got into the 7mm Mauser too deep because I never could get it to shoot well and didn't want to invest in the money so I am some what limited on brass but will make due. I have 13 once fired 7x57 brass and 19- .06 military brass converted to 7x57. The first loads with unchanged primer hole will be with military brass. All will be done with Winchester WLR primmers & 175g Jacketed Speer Mag tip bullets. The varget I got out of the Lee manual for 50446 PSI and the WMR I got off line and the pressure is unk.

3ea- 37.7 Varget / 3 ea- 48.0 WMR
3ea- 37.7 Varget / 3 ea- 48.0 WRM 1/8 hole
3ea- 37.7 Varget / 3 ea- 48.0 WRM 9/64 hole (.14)

Let me know what you think. Maybe I should drop the first 6 unaltered down a hair beings they are military cases and subject to higher pressures or should I use all military cases?

[joeb33050]

I don't know what WRM powder is. With 13 once fired 7X57 brass cases I'd load three sets of four, four with standard flash holes, four with .125 flash holes, and four with .140 flash holes. I'd be leery of the cases made from 30/06.
The Lyman 47th limits max pressure to under 46,000 CUP, I'm guessing because of the 95 Mauser used in testing. If yours is a 95 or non-98 Mauser, I think that 45,000 CUP should be the pressure tested at. If yours is a 98 Mauser, your load/pressure with Varget seems fine. In any case,. we need to know or have an estimate of the pressure fired at. Whatever you decide, please write everything down and be careful. I consider this an important test from a safety aspect.
Thanks for this;
joe brennan


JoeB

I am ready to get started on the project. Would have done it sooner but with the hoildays and had the flu this past week, I didn't have the time! I never got into the 7mm Mauser too deep because I never could get it to shoot well and didn't want to invest in the money so I am some what limited on brass but will make due. I have 13 once fired 7x57 brass and 19- .06 military brass converted to 7x57. The first loads with unchanged primer hole will be with military brass. All will be done with Winchester WLR primmers & 175g Jacketed Speer Mag tip bullets. The varget I got out of the Lee manual for 50446 PSI and the WMR I got off line and the pressure is unk.

3ea- 37.7 Varget / 3 ea- 48.0 WMR
3ea- 37.7 Varget / 3 ea- 48.0 WRM 1/8 hole
3ea- 37.7 Varget / 3 ea- 48.0 WRM 9/64 hole (.14)

Let me know what you think. Maybe I should drop the first 6 unaltered down a hair beings they are military cases and subject to higher pressures or should I use all military cases?

[mooman76]

JoeB
Mine is a spanish Mauser, not sure of the year but something like the 93 or so. WMR (Winchester Magnum Rifle) is an old discontinued powder. I only threw that in because I have allot, and not many applications to use it in but the main reason I threw it in is because it is the only ball type powder I have and I thought it might be good since I am going threw all this trouble doing it that it would be good to have another validation. That is if it makes it this far. I can drop it down to 45k , I was considering doing this because it is an older weopon. I have a few factory rounds left. I could dismantle them and use instead of the old military brass!

[joeb33050]

JoeB
Mine is a spanish Mauser, not sure of the year but something like the 93 or so. WMR (Winchester Magnum Rifle) is an old discontinued powder. I only threw that in because I have allot, and not many applications to use it in but the main reason I threw it in is because it is the only ball type powder I have and I thought it might be good since I am going threw all this trouble doing it that it would be good to have another validation. That is if it makes it this far. I can drop it down to 45k , I was considering doing this because it is an older weopon. I have a few factory rounds left. I could dismantle them and use instead of the old military brass!

You'l have to be the judge, but I'd hate to see the gun blow up and not have any notion of the pressure. Your call, for sure.
Thanks;
joe brennanl

[joeb33050]

I think that what I've copied below is the only factual information that's been posted-factual means not questions, not opinions, real stuff somebody did.

There are several reports that Quickload predicts MV well, predicts pressure poorly.

TRK is going to scan Phil Sharpe's article and send it. This shows pressure excursions with drilled flash holes.

My quote of John Barsness shows big pressure excursions with change in primer.
Bass Ackwards sees change in MV with change in flash hole diameter.
Larry Gibson sees no problems with drilled flash holes and some respectable velocities.
The Fouling Shot, January February 2007 "Velocity Check" by Grant Macomber says several things about this, one is "In my handloads, 20 grains of 2400 gives 1300, 1330, or 1400 fps mean velocity depending on the primer used."

Something's going on here with primers and flash holes.

I'd like permission from Bass Ackward and Larry Gibson to quote/use what they've written.

I'd like any DATA that anyone else has, and any suggestions.
Meanwhile we wait for MOOMAN in Las Vega to blow up the Mauser. I'm nervous when I don't hear from him.

Bass? Larry?
Thanks;
joe brennan

Joe

This might be a case of condeming a technique because of miss application (sorta like the use of dacron wads cuasing ringing). Those of use who drill out the flash holes (I use the #28 drill) do so with light loads of quick burning powder, i'e "squib loads". The reason is to prevent the force of the primer explosion from forcing the case forward and setting the shoulder back. The drilled flash holes also get the flash to the powder much quicker and reduces any "position sensitivity". Flash holes are drilled in rimless cases that headspace on the shoulder.

What do you mean by "full power loads"? Cases with drilled flash holes are meant only for reduced light loads and certainly not for anything approaching what I consider a "full power load", i.e. 180 gr jacketed SP at 2700+ fps in and '06. I have been sneaking up close to regular CAST bullet loads in the .308 with flash hole drilled cases, i.e. a 311291 over 4895. so far I'm up to the 1800 fps range without any signs of pressure problems. ES and SD of all loads with drilled flash holes are consistantly lower than with regular flash holes. I plan on stopping at 2200 fps (if I don't get any pressure signs) with that bullet as accuracy falls off past that with the 1-12" twist barrel I'm using. I am going slow and easy. Even if I succede I won't recommend it as I'm not seeing THAT much benifit and it's to easy to misinterprete it's application.

Larry Gibson

Joe,

I was shooting 55 grains (full case) of H-4895 with a 300 grain Barnes bullet in a 458X2. This load was used in unaltered cases with Fed 215 primers because it was borderline too slow for the bullet weight. Velocity was around 2300 fps. Same batch of cases that had flash holes opened, raised presure only slightly producing velocity of 2350 fps which established a false sence of security on my part.

Confident, the same cases were used with a 375 grain lead bullet and H-322. While working up a modest load we went to 55 grains and found that velocity exceeded 2200 fps at a predicted 55,000 psi with the standard cases. Accuracy was around 52 grains at 2100 fps. But this time, when cases were inadvertintly charged with 52grains that had large flash holes, velocity jumped to 2450 fps which Quickload estimated took 75,000 psi to produce. Cases were trimmed almost 3/16" on the enlarged flash hole cases, while the standards were quite fine.

Two powders with very close burn rates acted entirely differently as evidently H-322 had crossed over a threshold when using a heavier bullet. Those cases with enlarged flash holes could not be used for powders faster than H-322 without requiring a substancial quantity reduction. heavier bullets were worse than lighter offerings. Even pistol primers produced more velocity with 4198 in enlarged hole cases compared to magnum rifle primers did with the same charge in standard cases.

A similar pressure event happened with smaller holes than standard which cused poor ignition.

Back in the early 70s, Speer sold brass marketed under the Speer DWM brand. I believe that this excellent brass was made in Germany. Two previous boxes turned out to be very uniform compared to brass of this day, and the anneal was first rate. The third box purchased later apparently had flash holes that were too small. Certainly smaler than the prior purchases.

This caused erratic ignition with the same load successfully developed and used in the previous cases. Some loads produced very modest recoil and others flattened primers leaving visible extractor marks on the brass and swollen bases. Cases that were subjected to the higher pressue levels required extensive trimming and were retired after only one loading. Don't have the load anymore, but it was a mid range offering obtained from a reliable reloading manual at that time. The cartridge was a 7X57 using a 130 grain Speer. I belive the powder was 4320. After diagnosing the problem, the holes were opened the same as the prior brass, and the survivors lived a respectable reloading life.

Moral of the story is to always start low and work up any time you change any variable.

Bass Ackward on Cast Boolits

joe b

So then to clarify with the flash hole drilled cases; are you loading (going to test) the 7mm Mauser to normal cast bullet velocity for this cartridge, i.e. a 160-175 gr cast bullet over a medium burning rate powder to 1800-1900 fps? Or are you loading the 7mm Mauser to factory (European) pressures with 139 - 175 gr jacketed bullets to 2800 to 2400 fps respectively?

I ask because I have already snuck up to 2044 fps with the 123 SKS/AK bullets the '06 over 18 gr Unique with well fire formed cases and the flash hole drilled with a #28. Those loads do not exhibit any signs of excessive pressure being applied to the primer. I have shot several hundred of them so far. I also have been working with the .308 with flash holes drilled and 311291 over 4895. I'm up around 1800 fps and again no sign of excessive pressure on the primer.

Larry Gibson


OK, I looked it up in MY Funk and Wagnalls:

Let me quote from Philip B. Sharp’s reference Complete Guide to Handloading beginning on page 35:

Actual tests show that reaming out flash holes to a larger size will slightly increase velocity and greatly increase pressure! Furthermore there will be a tendency toward primer leakage and the stretching of pockets with normal pressure loads. To verify these findings, the author asked the Hercules Experiment Station to try reaming flash holes oversize and report findings. The .270 Winchester cartridge was chosen for the experiment, non-corrosive priming, 130 grain bullet, and a full charge of HiVel #2. Normal flash-hole size in 0.80 inch, and this was tried, the loading being repeated with the vent reamed to .101.

With the normal flash hole, the maximum velocity for the series of twenty shots ran 3067 f.s. instrumental, with 2984 f.s. minimum. Average or mean velocity was 3036 f.s. Pressure tests for the twenty shots showed 56,600 pounds maximum, 50,400 for minimum and 54,600 for the mean or average. Using the same components, the flash hole was reamed to .101 and the test repeated. Maximum velocity jumped to 3138 f.s. instrumental, minimum was 3066 f.s. while the average was 3105, and average increase of 69 f.s. The real problem occurred with the pressures. Maximum jumped to 68,800 pounds, minimum was 58,000 pounds, while the mean ran 63,600, and increase of 9000 pounds with a velocity increase of only 69 f.s. These figures should be self-explanatory. Don’t ream out your flash holes to larger than normal size. Such reaming as is necessary should be solely for the purpose of removing burrs.

This 3rd edition 2nd revision is copyrighted 1937, 1941, 1949, 1952 and 1953 published by Funk and Wagnalls Company, New York.
__________________
trk
aka Cat Whisperer

Pressure is problematical. "Quickload" estimates pressure and velocity without regard to the primer type. Velociy and pressure are not related as I once thought.
Everythin I've read about it tells me that increased flash hole diameter increases pressure, nothing I've read tells me that that increase is enough to blow up the rifle.
trk quotes a 9 ksi average pressure increase with enlarged flash holes.
Here's a reference showing a 12.8 ksi pressure increase caused just by changing primer type. And I don't think the gun blew up.
Handloader, August 2005, "Velocity and Pressure" by John Barsness.
The author cites "Any Shot You Want", the A-Square loading manual concerning variations in pressure with changes in primer. From that manual, on pg. 65 the table "Primer Experiment" shows: 7MM Remington Magnum, 160 grain Sierra boat-tail, 66.0 grains of Hodgdon H-4831 and Winchester cases.
CCI 200 (standard) 3011 fps, 54,800 psi
Rem 9 1/2 M (magnum) 3041 fps, 59,300 psi
CCI 250 (magnum) 3039 fps, 61,500 psi
Fed 215 (magnum) 3036 fps, 61,400 psi
Win WLR (standard) 3024 fps, 64,400 psi
Win WLRM (magnum) 3045 fps, 67,600 psi

The author then performed a test on a ".300 Winchester Magnum with a 23-inch barrel, the load a 180-grain Nosler Partition with 75.0 grains of Hodgdon H-4831 in Winchester cases."
Fed 215M, 2924 fps, 63,800 psi
CCI BR2, 2920 fps, 55,800 psi
Win WLRM, 2991 fps, 70,100 psi

It is clear that pressure varies greatly with primer, while velocity varies much less.

So, pressure varies by flash hole diameter, and even more by change in primer type/brand/whatever it is.


joe b.

[Bass Ackward]

I'd like permission from Bass Ackward and Larry Gibson to quote/use what they've written. joe b.

joeb,

Fine by me.

Bass

[leftiye]

Joe, I'd be quite interested in the feasibility of using enlarged primer flash holes to ignite slow burning powders in low pressure loads in straight wall cases like 45-70. As an adjunct maybe to the effect on full power loads maybe.

[mooman76]

JoeB

I finnaly got the test done but it proved to be inconclusive. I loaded 3x3 each 3 unchanged, 3 1/8" hole and 3 9/64"(.140) of once fired factory brass with Winchester WLR primers and 35g of Varget each round weighed twice for accuracy and 175g Speer bullets. All rounds including the once with the enlarged primmer hole showed pressure signs in the head including two near head seperations. The two that showed near head seperation were the ones with the unaltered primmer hole and one with the 1/8" hole.

[joeb33050]

JoeB

I finnaly got the test done but it proved to be inconclusive. I loaded 3x3 each 3 unchanged, 3 1/8" hole and 3 9/64"(.140) of once fired factory brass with Winchester WLR primers and 35g of Varget each round weighed twice for accuracy and 175g Speer bullets. All rounds including the once with the enlarged primmer hole showed pressure signs in the head including two near head seperations. The two that showed near head seperation were the ones with the unaltered primmer hole and one with the 1/8" hole.

Mooman 76;
Thanks for doing the test. Was there any damage to the rifle?
May I quote your results?
Bass Ackwards;
Can you give us a pressure estimate from Quickload on this load?
Thanks;
joe brennan

[mooman76]

Yes you can! The rifle held up good. Unfortunately it isn't that great of a gun. I believe I possibly have a headspace problem due to the facts and that also might be why I never could get it to shoot worth a darn!
According to Lee modern loading second edition 50446 P.S.I. or 45,500 C.U.P. by Hogdens manual.

[trk]

Was the 'headspace' changed in the process?

Did the bases of the cartridges expand? (Do they still slide into the shell holder as easily as before?)

[joeb33050]

Yes you can! The rifle held up good. Unfortunately it isn't that great of a gun. I believe I possibly have a headspace problem due to the facts and that also might be why I never could get it to shoot worth a darn!
According to Lee modern loading second edition 50446 P.S.I. or 45,500 C.U.P. by Hogdens manual.

Are these pressures from the Lee and Hodgdon manuals with 35/Varget? I had a pm that this load is 36,000 psi according to quickload. The pressure or an estimate is important.
Where's Bass Ackward when we need him???
Thanks;
joe b.