Explain this

[Jim]

I fired two different cartridges in my Spanish Mauser today. One was a Lake City 7.62X51. The other was a Winchester .30-06 that had been converted to a .308.

The load was a Lee .311-100-1R over 6 grains of Bullseye. Primers were large rifle.

When you go to the site, your cursor will allow you to click on the photo. You will then be given the opportunity to magnify it with the indicator. Look at the primers and explain to me why there is such a difference in the print.

http://fgsp.wordpress.com/2010/12/10/lc-vs-commercial-brass/

[fishhawk]

has to be the differnce in cast volume in my opinion. steve k

[spqrzilla]

Or neck tension, did you do any neck turning after resizing to .308?

[Moonie]

odd, looks like they were fired in 2 different rifles, the primer strikes are soo different.

[rtracy2001]

Case capacity, neck tension, how about trim length? All of those can affect pressure.

Did you weigh the charge or use a meter?

How about seating depth?

Which one was fired first? could there be a leading problem?

[leftiye]

The military brass is thicker.

[Jim]

I checked the volume of each case with WC820 powder.
LC- 51.5 gr.
Win- 52.3 gr.

That's less than 2 percent difference in charge weight.

I did not turn the neck on the Win. case. I did, however, f/l size both with a .305 sizing ball.

Trim length was checked to 51 MM.

Each charge was digital scale weighed.

COL was checked on each with a caliper.

I don't mean to sound boastful or prude, but my lube eliminates leading.

Guys, I'm not arguin', I'm just answerin' ya' questions. I'm as puzzled as y'all are. Beats the hang outa' me what caused it.

And, yeah, it DOES look like they were fired in two different rifles. I always look at my primers. every one. I looked at these and thought "What the....?".

[waksupi]

Jim, check for a broken firing pin.

[swheeler]

Looks like ignition problem, but when your touching off only 6 grs of BE one would think a LR primer would suffice with powder in any position, but evidently not? maybe ream out the flash holes.

[Jim]

Ric, fired this rifle many times. If the pin was broken, would it continue to fire? Not a gunsmith, so I wouldn't know.

Forgot to mention, barrel was tipped up prior to firing each round.

[Jim]

Ric, fired this rifle many times. If the pin was broken, would it continue to fire? Not a gunsmith, so I wouldn't know.

Forgot to mention, barrel was tipped up prior to firing each round.

[docone31]

That is an issue there.
With 6 gns of anything in a case with a capacity of 50gns, ignition is an issue.
I do not mean slow ignition, I mean explosive ignition.
Perhaps, the powder in the LC case had spread though the case more than the -06 case.
The primer flame would have ignited all of it, rather than progressive ignition. You perhaps had a boom! rather than a Blam.
Might be an answer.
Maybe not.

[Jim]

I dunno, Doc. I can't count the number of times I've loaded very small charges of fast powder under light boolits. Never seen this before.

[azcruiser]

are the primer flash holes the same look at them when you de prime them. LC is Thicker than Win so that could be it . I would change powder 6gr in that case is not much.try trail boss
6gr will fill up over 1/2 the case .

[454PB]

Looks like the flattened primer may have been caused by excess headspace. The firing pin pushes the case forwards, the primer ignition and pressure pushes the primer partially out of the pocket, then the case is slammed back against the bolt face as the pressure increases. It's a fairly common occurrence, and especially with reformed brass.

[lylejb]

The answer is in the tightness of the primer pockets.

For the LC case, the primer set back upon ignition, then was smashed when the case thrust back against the bolt head.

For the Win case, the primer did not set back. the Primer and case thrust back against the bolt head as one piece. Theirfore, no smashing.

I've seen this before, with light loads. I've seen light plinker loads that primers look flatter than max loads, due to primer set back and smashing.

It LOOKS like high pressure, but it's not. It doesn't actually hurt anything.

Hth

[AZ-Stew]

I'm with 454PB.

Regards,

Stew

[docone31]

I had a big bang one day.
I was loading lightly. I thought if I tipped the barrel up they would be ok. Well, one day Boom! It exploded more than burned. No damage, but the case was split up the side.
As a guy at the range explained it, the powder gets ignited by the primer. This in turn progressively ignites the rest of the powder. In this case, the primer fired over the entire charge. It burned all at once.
That charge makes tremendous pressure. I have had it happen.
That was the last light charge I did. Not because of the incident, I just loaded to full tilt. I was now going for distance, rather than short range.
Basically, a tip up that time was not enough. I have had it happen in a pistol also. A Ruger SBH. They are strong pistols for sure. With 6gns of Blue Dot, the primer went into the firing pin hole! Again, I had a light load that went the entire lenght of the case, low enough to let the primer fire it all at once. I never loaded below 10gns after that. I went to 2400, and compressed case loads. I shot IHMSA at that point. Didn't do well, but met some great folks, adn had the time of my life!
Won a bunch of trophies, but that was mostly for attendance. I never missed a meet.
Dang, I had fun .

[S.R.Custom]

Not enough information here to say...

Some of the variables that come to mind: Flash hole diameter. Headspace. Thickness of brass at the neck. Proximity of the seated bullet to the lands. And the list goes on...

Personally, I think it has to do with the vagaries of putting a small amount of powder in a relatively huge space and expecting it to burn the same way each time. Try the same test with an appropriate load that approaches a loading density of 95%, and I'll bet you dollars to doughnuts you don't get such wildly different pressure variations.

[jcwit]

Did one chamber harder than the other

[buck1]

I would be tempted to say a bit of detination. The flame from the primer pushes the boolit in to the throat hard, but pases over the powder not lighting it . Then the powder sitting in the bottom (side) of the case lights with a boolit stuck in the throat. you get a pressure spike untill the boolit moves from it stuck position.
Thats the only way I can see the LC primer getting that flat with 6.0 Bullseye.
Thats my Guess...Buck

[waksupi]

Yes, lots of firearms will fire for awhile with a broken firing pin, until they totally give up. Sharps have a fairly high breakage rate, and will fire, but accuracy goes down the drain. If there is enough alignment in a bolt action, they will also fire, until it gets a serious jam in the bolt sleeve.

[HORNET]

How's the case neck clearance on the loaded round in the LC case? Just because the WW case is heavier doesn't mean that its distributed where it needs to be after reforming. OR 454PB or lylejb could be right and it could be a little headspace/ loose primer pocket issue.

[Jim]

7:40 AM

Some very good observations brought forth. Lemme get my startin' fluid an' I'll take a look at a coupla' things.
I'll deprime and photograph the primers and try to caliper the pockets.
I'll letcha' know when the photos are up.

[9.3X62AL]

It's posts/threads like this that have almost convinced me to STOP loading relatively small amounts of fast powder into large cases. I don't do much of it any more, though I'm right in the middle of a run of 250 Savage with RCBS 25-85-CB and 6.5 grains of Unique. I'm a muzzle-raiser with any such load, and to date I haven't experienced anomalous reactions like that discussed here. I'd prefer doing without such events, myself.

[Jim]

The ARTICLE (http://fgsp.wordpress.com/2010/12/10/lc-vs-commercial-brass/) has been updated with a photo of the cases and primers. More information has been added in text above the new photo.

[cajun shooter]

Some years back in one of the gun mags that I read at the time there was a article about light loads being dangerous. They showed a couple of rifles that had damage from various loads that were used. It is past my level but one thing I 've always done is to shoot the same brass with each load be it large or small. I remember the author of the article saying something about detonation but that it was not known at the time why or how it was caused. They did recommend using a IMR 4759 IIRC for any type of gallery load.The article stated they could explain why a overload destroyed a rifle but not the small one. I also stopped doing my mouse loads after that.

[John 242]

How light is too light? I usually load around 10 to 12 grains of Unique in the .303 British and 7.62 Russian and haven’t had a problem with hang fires or flattened primers. I’ve had mediocre accuracy, but I'm not exactly David Tubb, so it could be operator error. Anyway, how light is too light?

[azcruiser]

You can see by the primer in the LC military case that it was crimped by the ring around it and that held it more in place . The other case was not crimped primer is smooth so it moved back.
In my mind I have seen as many guns break from pressure spikes from low powder charges as
over charges. And yes I know that the labs don't agree with what I have seen .so don't shoot the poster . But try That TRAIL BOSS Powder 9 o/z has the same volume as 16 o/ of most other powders and you will never double charge with it . My 2 cents

[Jim]

Actually, AZ, the primer cup in the LC case is not crimped. I have been given some LC cases that were, but they all get chamfered before loading.

[Jim]

I pulled the firing pin. Nothing wrong, no breakage, not bent.

[geargnasher]

Looks like the flattened primer may have been caused by excess headspace. The firing pin pushes the case forwards, the primer ignition and pressure pushes the primer partially out of the pocket, then the case is slammed back against the bolt face as the pressure increases. It's a fairly common occurrence, and especially with reformed brass.

My take on it as well. I've had primers look like that on cases that were sooty around the necks from low pressure loadings, too much headspace lets them back out a touch and then get mushroomed on the way back in under full burn pressure.

Gear

[Bloodman14]

Is it just me, or does the LC primer pocket look bigger than the Winny pocket? I also think that the 'crimp' in the LC primer is actually a 'fold' from being popped out and then smashed back into the pocket.

[Jim]

I didn't think of that. I just miked 'em. They're both .209, on the button.

As for head space, both cases were fire formed in this rifle prior to the trouble mentioned. Would that not fully form the cases to eliminate head space, or not? I'm not sure, to be honest with you. I was always under the impression that fire forming eliminated head space problems. Am I wrong?

After much discussion, I'm beginning to believe I had a slight case of SEE. Not enough to blow the gun because of the small charge, but enough to max out the primer.

[454PB]

Did you have the full length resizer set to touch the shell holder?

Fire forming only works if the sizing die is set so that you never push the shoulder back any more than required for chambering.

As an example, I own multiple rifles that use belted cases. Theoretically, a belted case headspaces on the belt, but I've found that setting the full length resizer so it touches the shell holder shortens case life to about 3 or 4 firings.

I established the proper setting by finding a fired case that WILL NOT chamber, then gradually cranking down the sizing die a 1/4 turn at a time until that case would allow the bolt to close with some resistance. I then turned the die another 1/4 turn and set the lock ring. My cases last from 10 to 15 firings now because I'm using the shoulder instead of the belt for headspacing. The same principle works for rimmed rifle cases

In your case, if you fire formed and then had the resizer screwed down enough to touch the shell holder on the next resizing operation, you would be returning that fired case to it's original configuration.....and possibly a slightly excess headspace condition.

[Jim]

After fire forming, I use a neck size only die. I set it to stop .050 shy of the shell holder. The inside of the die never touches the shoulder. That way, the case is truly fire formed.

[madsenshooter]

I didn't think of that. I just miked 'em. They're both .209, on the button.

As for head space, both cases were fire formed in this rifle prior to the trouble mentioned. Would that not fully form the cases to eliminate head space, or not? I'm not sure, to be honest with you. I was always under the impression that fire forming eliminated head space problems. Am I wrong?

After much discussion, I'm beginning to believe I had a slight case of SEE. Not enough to blow the gun because of the small charge, but enough to max out the primer.

Yes, but the firing pin fall, and primer detonation, is sometimes strong enough with a light load to push the shoulder forward and create the excess headspace. With really light loads flashholes are sometimes enlarged so there isn't enough pressure created to push the shoulder forward. Your chamfer of the LC primer pocket, looks a little broad, I know, sometimes they have to be to get all the crimp, but it helped swage some of the primer's shape, and, it appears there was a little less area for the primer edge to grip as pressure built, thus it backed out, before the previously pushed forward case started back. Why didn't the Win push forward also? Shoulder may be thicker, flash hole looks minutely larger, more surface of the primer pocket for the edges of the primer to grip. Another possibility is that there were a few grains of powder got into the pocket, right in there with the primer to increase pressure there. That's something Phil Sharpe did to prove primer condition was not a good indicator of pressure. Put a few grains in the primer pocket, he'd get flat primers, but the lab was telling him pressure was the same as an identical load w/o powder on top of the primer. Your chamfer is part of the problem, I've done the same thing when all I had to cut them with was a little pocket knife, some would expand to the chamfer, some stay nice and rounded, my cutting technique with the Barlow wasn't very exact. Now I swage them out.

[jecjec13]

Jim, I dont know if this will help but I have an old lee enfield 303 british gun with too much headspace as most of the old enfields did. I load 180 gr cast over 9 gr. red dot. I had the same problem until a friend at the range ask if I was using any filler in the case. At the time I was not. I did some work trying different fillers such as grits, oatmeal and sever others I finely settled on used dried coffee grounds as a filler to keep the powder at the primer. Load 9 gr. red dot fill the case to the top with the coffee grounds and press the boolit down to hold everything snug. I have not had the problem with flat primers again. Dont know if it will help but thats my 2 cents worth.

[Mk42gunner]

Jim,

Here is my opinion, and theory (with this and a dollar plus tax you can get a cup of coffee at my local McDonald's).

When the firing pin fell it: 1. Ignited the primer, while pushing the case forward, however minutely. 2. The primer backed out of the primer pocket. 3. The powder ignited and expanded the case. 4. The casehead of the reformed .30-06 pushed over the primer. The LC case didn't because the primer pocket was tighter, thus causing the primer to protrude enough to flatten as the casehead came back.

Incidently, why form .308 cases from .30-06?

It took refreshing the page three times to view your pictures; I severely dislike dail-up, but won't move into town.

Robert

[NHlever]

The answer is in the tightness of the primer pockets.

For the LC case, the primer set back upon ignition, then was smashed when the case thrust back against the bolt head.

For the Win case, the primer did not set back. the Primer and case thrust back against the bolt head as one piece. Theirfore, no smashing.

I've seen this before, with light loads. I've seen light plinker loads that primers look flatter than max loads, due to primer set back and smashing.

It LOOKS like high pressure, but it's not. It doesn't actually hurt anything.

Hth

Yes, I have seen this before using light loads of fast powder, and agree that it is nothing to worry about. I would mike the case heads to see if there is any difference in case expansion. That will tell you. I have also seen primers that protrude from the case after firing light loads, particularly in old lever guns that might have a touch of extra headspace. One can almost measure the headspace by measuring the primer protrusion. Each time you fire a gun the case is first pushed ahead by the force of the hammer / striker blow, and then moves rearward as the pressure rises, and reseats the primer. An oily case / chamber can change how much that happens, the shape, or in your case the thickness of the case can affect it, and there are many other variables. Because a .308 case is thicker, and has less taper than a 30-06, you will get the same kind of different signs using loads of equal, but lower pressure in both for example.

[Jim]

My caliper shows .209 of both primer pockets.

I dunno, fellas. This one's got me shakin' my head.

[1Shirt]

Jim, For what ever it is worth, I never use Bullseye or very fast powders in a rifle. In most of my cast loads for everything from 243 up to 45-70, I use 2400 or 4759, and in most cases use a dacron filler.

I have as of late also been using a fair amount of Trail Boss (no filler) and have had a lot of satisfying sucess with it as well. After a bad experiance, if my charges of powder do not come at least half way up to the inside of the case, I weigh each finished case on a little battery scale for consistancy. Of course cases must be the same mfg, and preferably the same batch of production.

I long ago stopped loading the same load in a batch that I was loading with ctgs of different mfg and weight. Also am very careful of reformed mil brass, due to thickness and increased weights, and reduce charge percentage for initial loading of same due to increased pressures.
1Shirt!:coffee:

[onondaga]

Looks to me that the powder detonated in the LC case. Detonation of light charges is an erratic thing and doesn't always happen. When it does happen you see the typical over-pressure signs that are puzzling with such a low charge when it detonates instead of burning as a propellant. You had a lot of pressure there, more than would be possible from slightly different case volumes, or loading differences with similar bullet weights when the charge was the same. Low volume light loads are more likely to detonate even with the best loading and shooting methods.

I am a bad offender. When I began to experiment with reduced loads in .458 Win Mag a several years ago I had one detonation so severe that I had case separation and primer blowout. The muzzle flash terrorized everyone at the range. I did a lot of studying and settled on the controversial use of ballistic fillers. With careful calculations adding the filler weight to the bullet weight for a total projectile weight with load safety. I have gotten perfect reduced load ignition in over 2000 test firings with BPI Original Ballistic filler with reduced charges and 105% capacity loads including filler. That stuff acts as a good gas check on plain base boolits also. I get no leading, no tumblers, no ringing and the bore finish is mirror like. The bore on my Colt Sauer Grand African has kept the wonderful slick shine since new, circa 1984 even with over 10,000 rounds fired. Only a few hundred rounds were jacketed bullets when the rifle was new.

Gary