Downside to oversize boolits?

[Silvercreek Farmer]

Been reading this forum for months, but still have a newb question from time to time, so here goes:

Seems like undersized boolits are a constant theme. A boolit leads and doesn't shoot well at .xxx, beagle the mold or what ever you have to do to get a .xxx + .001/.002 boolit and all of the sudden groups tighten up and leading disappears. "Fit is King" gets repeated all the time. Commercial cast boolits tend to be undersized and several manufacturers sell guns with oversized bores. What gives? What's the downside to commercial casters and mold manufacturers setting up for an oversized boolit to begin with (as long as it will chamber reliably)? Pressure? Accuracy?

I don't know if I have seen a single post where someone has contributed increased performance to shrinking a boolit...

[paul h]

Some guns have tight dimensions and hence an oversize bullet will not chamber in them. Bullet manufacturers are more interested in their bullets fitting everyones gun, and honestly not all shooters are capable of shooting to their guns accuracy potential. Hence, they'll recieve more bad publicity when their bullet won't chamber in Enis' gun than the good publicity they'll recieve when Clyde shoots a really small group.

[44man]

Been reading this forum for months, but still have a newb question from time to time, so here goes:

Seems like undersized boolits are a constant theme. A boolit leads and doesn't shoot well at .xxx, beagle the mold or what ever you have to do to get a .xxx + .001/.002 boolit and all of the sudden groups tighten up and leading disappears. "Fit is King" gets repeated all the time. Commercial cast boolits tend to be undersized and several manufacturers sell guns with oversized bores. What gives? What's the downside to commercial casters and mold manufacturers setting up for an oversized boolit to begin with (as long as it will chamber reliably)? Pressure? Accuracy?

I don't know if I have seen a single post where someone has contributed increased performance to shrinking a boolit...
Fit works but over size can also be bad. Fit to the bore or a little over is best but if you go too soft and a boolit skids the rifling and opens gas channels it will not matter how much "FIT" you have. Soft can also slump a boolit so bad the GG's are gone before it enters the bore and so is the boolit design you had a special mold made for.
Some say make a revolver boolit way over throat size, that is wrong too.
It is true that many bought boolits are under groove size and so are many molds. You will be told to make the lead softer to "obturate." Not good either.
The 45-70 is an example. Many bores are .459" to .460" yet boolits and molds are .457".
Under size never works. But there is no need to go too high over groove size either.

[geargnasher]

Commercial cast bullets have some challenges to overcome which are typically detrimental to performace. To withstand shipping heat and being dropped/banged around, the bullets have to be cast from an alloy that's harder than often needed to shoot well, the lube is very hard and has a very high melt point, and the designs tend to be bevel-based if not gas-checked so that the effects of base dings during shipping are minimized. As for the undersize thing, I don't know for sure but I suspect that is the result of a variety of factors involving most common fit, commercial mould limitations, and "we've always done it that way". I rember a thread here some time back started by someone high up in a large commercial mould production company asking about how to size boolits, it was obvious that he had virtually no idea what the product was supposed to do. at least he was trying to learn.

If you'll notice, the custom mould makers are also shooters, and know how to design their products. The bigger, mass-market producers seem to have more of a division between production and shooting. After all, it's common knowledge that .38 Special bullets have to be sized .357 and cast from pure linotype alloy, and that MicroGroove Marlin rifles can't be loaded to anything faster than 1600 FPS, right?

I do give Lyman a lot of credit for getting an expert competitive shooter and gun writer who casts his own boolits to author their latest edition of The Cast Bullet Handbook, but the truth is that not very many folks in the greater scheme of things really know what works best when shooting cast, and the common knowledge driving the industry is more like common ignorance.

That's why we have such a market here for custom mould manufacturers, and why we roll our own in the first place.

Gear

[H.Callahan]

After all, it's common knowledge that .38 Special bullets have to be sized .357 ...
I think there is a lot of this going on, too. Remember that a lot of purchasers of commercial cast are not versed in the differences between jacketed and cast. There are a lot of them that are just looking for a cheaper alternative to shooting jacketed. When the go to buy cast, they make the mistake of equating cast with jacketed. They WERE buying .357 diameter jacketed bullets, so it should make sense that one would buy .357 diameter cast bullets, right? I would bet that if they kept track of all the cast bullets sold commercially, that there would be a spike in the diameters that were nominal for the caliber.

When I very first started casting in the early 1970's I got caught in this (remembering that there was no CastBoolits at the the time and very little casting information available). My very first sizing dies were a .357 and .429 for 38/357 & 44. I wasn't getting good results and almost gave up casting until I finally did read something that told me that I generally needed to go bigger with cast. That made all the difference.

[popper]

Only down side is if it won't chamber or increases pressure too much.

[geargnasher]

Oversized cast boolits increasing pressure is another myth I'd love to see destroyed. It's been proven that even .004" increase in boolit size over groove diameter made no measureable increase in chamber pressure.

Gear

[prs]

From my experience, if it fits (chambers) it shoots even if it is over sized for the barrel. Lead boolits are sized rather easily by the barrel. My Ruger 45 Colt BVs are an example. My moulds drop .454+, the sizer (if I use it) is .454, the chambers are huge and the loaded rounds rattle about in there, the cylinder throats are .453 and the barrels are real close to .451. No problems at all. But a barrel can not "up-size" a boolit; if too small you are just screwed.

I agee with the thing about commercial casters, if they were gonna shoot those boolits, they would be correct size for their guns.

prs

[prs]

Oversized cast boolits increasing pressure is another myth I'd love to see destroyed. It's been proven that even .004" increase in boolit size over groove diameter made no measureable increase in chamber pressure.

Gear

Agree with that too.

prs

[EdS]

When I started casting for my revolvers 50 years ago, I read Elmer Keith's articles in which he said to size bullets .429 for the .44 Magnum. So, I set up and did just that. When I got leading at any velocity over about 1100 fps, with four or five different lubes; I was frustrated to say the least. Then, by luck, I bought the hollow base version of the famous 429421 and when I cast bullets from 16:1 to 20:1, my leading troubles all but disappeared. -Ed

[Char-Gar]

Been reading this forum for months, but still have a newb question from time to time, so here goes:

Seems like undersized boolits are a constant theme. A boolit leads and doesn't shoot well at .xxx, beagle the mold or what ever you have to do to get a .xxx + .001/.002 boolit and all of the sudden groups tighten up and leading disappears. "Fit is King" gets repeated all the time. Commercial cast boolits tend to be undersized and several manufacturers sell guns with oversized bores. What gives? What's the downside to commercial casters and mold manufacturers setting up for an oversized boolit to begin with (as long as it will chamber reliably)? Pressure? Accuracy?

I don't know if I have seen a single post where someone has contributed increased performance to shrinking a boolit...

Are you talking about rifle, sixgun or pistol bullets here? The answer to your question will vary quite a bit without knowing what you are talking about.

[runfiverun]

airc at .004 the pressure goes up more.
up till then every thou is something like 300 psi.
then it jumps up to something like 6-700 psi.


grossly oversized is NOT what you want, the old "just make them .002 oversized" advice comes from throats and bbl's not being measured.
we all know every 30 cal bbl is 300x308,and......
so just make them .310 diameter, put 10 grs of unique in the case and go shootin.... [sarcasm button on]
yeah, that will "work",,,,,,,well? maybe,maybe not.

[geargnasher]

airc at .004 the pressure goes up more.
up till then every thou is something like 300 psi.
then it jumps up to something like 6-700 psi.


grossly oversized is NOT what you want, the old "just make them .002 oversized" advice comes from throats and bbl's not being measured.
we all know every 30 cal bbl is 300x308,and......
so just make them .310 diameter, put 10 grs of unique in the case and go shootin.... [sarcasm button on]
yeah, that will "work",,,,,,,well? maybe,maybe not.

Indeed. Correct fit is what's important, just about every gun seems to need something different. There are some designs, like many of the rifle boolits designed by 45 2.1, which cast large enough for most any gun in the caliber intended and are shaped to fit the throats. It is up to the user to size the bands to fit the throat, the gun will take care of the rest. Two-diameter bore-riders are much more difficult to fit. The commercial guys trying to make "one size fits all" boolits that are ready to load really can't hope to achieve much more than "works ok in most guns and won't get us sued". It's a tough row to hoe for those guys. The production mould makers should make the boolits large enough that the end user can make boolits to fit the largest throat expected with the minimum spec alloy, and then they have something to work with. Casting boolits yourself usually means you also expect to have and use the sizing/lubing equipment too, so can make your boolits fit most guns, whereas the commercial casters have to find an average for pre-sized and lubed bullets.

Gear

[beagle]

Fit's the thing for sure. The only downsize to oversize bullets is that they're hard to chamber. I have a 429421 that will drop a .434" bullet. I tried sizing .433" but they were very hard to chamber in my two SBKs so I dropped back to .432".

They shot well but I like fairly easy chambering.

I can't think of a case where an OS bullet would be a problem with normal reloading practices./beagle

[Larry Gibson]

Oversized cast boolits increasing pressure is another myth I'd love to see destroyed. It's been proven that even .004" increase in boolit size over groove diameter made no measureable increase in chamber pressure.

Gear

I have to disagree with this. I have been pressure testing this exact question in several cartridge/calibers. In the .308W with AA4350 under the 311466 the psi increases about 5,000 psi between bullets sized .308 and those left at .314. I have measured such differences many times and the measurement of such is easily reproducable.

Runfiverun's comment of; "airc at .004 the pressure goes up more.
up till then every thou is something like 300 psi. then it jumps up to something like 6-700 psi." is very close to what actual testing shows.

This is with cast bullets only. Within the normal psi with cast bullets used where they are a reduced load this poses little problem. However, in some firearms where loads are at the top end an increase of such psi from larger than needed cast bullets, especially harder cast ones, can put loads over the top. That is not good........:cry:

With jacketed bullets it is a very different story, be very careful with oversized jacketed bullets..

Larry Gibson

[Larry Gibson]

I should add that while "fit is king" I do not think "fit" necessarily means "oversize". In regards to commercial cast as per the OP's question I've found that hard cast commercial bullets in revolvers will enerally shoot well if relubed with a better and softer lube. This is eaven if they are .001 - .004 smaller than revolver throats but are at or .001 .002 over the barrels groove diameter.

I have and do shoot lots of commercial hard cast bullets and they shoot very well, not the best always but very well none the less. Commercial soft cast shoot better, especially if they are FB'd. Conversely I've found that even the best of cast do not shoot all that well if sized to throats that are .004+ over actual groove diameter. This is with revolvers and with rifles.

I prefer my cast bullets to 'fit" at throat diameter, whether a revolver or closed breach chamber (rifle or handgun). I find the best accuracy to most oten be found there. However, in revolvers with hard cast commercial I find bullets witin .002 to shoot very well.....if they are relubed with a good lube.

Larry Gibson

[geargnasher]

I remember the results I was reading were based on .45-caliber rifles operating at lower pressures. Good to know about the high-pressure .30s. But basically, you aren't going to blow a gun up even if dancing with the upper limit if you go .004" over groove, an unlikely even in a .30-bore anyway due to throat size and chamber neck limitations. What was the case neck clearance in your .308 with a .314" boolit stuffed in it?

Gear

[Larry Gibson]

Gear

I'm sure everyone who has unintentionally damaged or blown up a gun never thought they would. "unlikely"....probably but you stated emphatically "Oversized cast boolits increasing pressure is another myth I'd love to see destroyed" . It is not a myth and the caution and knowledge that it does indeed raise psi should still be there.

"What was the case neck clearance in your .308 with a .314" boolit stuffed in it?"

.002", necks were turned to ensure the bullet wasn't sized down nor "pinched" by the chamber neck. I am a little scientific in my testing so I was aware of and eliminated that potential problem as I was only interested in measuring the psi difference in different diameter cast bullets. The thinner neck should have resulted in a small decrease of the overall increase of psi as a result of a smaller amount of "bullet pull" with the slightly thinner case necks.

BTW; the psi difference mentioned is the result of 10 shot tests strings with each diameter of bullet as per SAAMI standards.

Larry Gibson

[softpoint]

Oversized cast boolits increasing pressure is another myth I'd love to see destroyed. It's been proven that even .004" increase in boolit size over groove diameter made no measureable increase in chamber pressure.

Gear

I used to read everything PO Ackley wrote. He once claimed re-chambering a 30/06 barrel to accept a .35 Whelen cartridge. Strapped the rifle down to an old tire, ran a string out to the trigger and let her rip. Claimed the rifle fired the cartridge with no ill effects! Ackley had lots of barrels and war surplus actions to play with, and play he did. He performed a lot of these kind of experiments that most folks don't have the resources to do. So at least in one experiment, a grossly oversize bullet didn't destroy the gun.

[RobS]

Question for the revolver??? Say a person shoots .454 boolits in a revolver with .4525 throats and then into the .451" barrel. Seems like things would be minimal here regards to pressure increase. Of course those who have inquisitive minds will say now why in the hell would you do that and in my case I shoot a lever action with a larger bore diameter than the revolver; I'm loading for the combo. I see little difference over the chrono and will see more of a velocity increase when I go from air cooled WW boolits to water quenched or heat treated WW boolits.

[Larry Gibson]

and will see more of a velocity increase when I go from air cooled WW boolits to water quenched or heat treated WW boolits.

Probably a reason for that related to increased psi.

Larry Gibson

[geargnasher]

I was just discussing this morning with someone the subject of an individual who rechambered an Arisaka to .30-'06 and fired a factory jacketed round in it while measuring the chamber pressure. After the bullet engraved the pressure was actually lower than with the proper ammo in the original chamber. I suspect since more energy was needed to force the grossly oversized bullet into the bore( probably converted to heat), there wasn't enough left to maintain the same pressure level for the remainder of the trip down the bore.

Guns do weird things sometimes. Sometimes they blow up for no readily apparent reason, sometimes you can't seem to MAKE them blow up. Same thing with internal combustion engines!

Gear

[Sonnypie]

From my experience, if it fits (chambers) it shoots
prs

Are you a postman?
You remind me of the post office commercial...
If it fits, it ships! :lol:
__________________________________________

I like perimeters. I like Standards of some sort.
So in order to have a sibilance of repeatability, I like to use Rotometals Lyman #2 alloy for my 30 cal bullet metal. And a single cavity mold.
Then, I size the bullets @ .002" over my slugged bore size.
So I know what the metal is, I know what the single cavity mold drops, I know my bore size, and I reamed my sizing die to size those specific bullets to my specific size.
For all that I expect to be able to have a repeatability round after round.
To me, to do otherwise (IE: Shoot them as they drop from the mold) is... well... inaccurate.
After all, I took casting back up to be able to improve over "store bought" bullets.
Otherwise, why bother at all?
My idea is to have a precisely over-sized bullet I can repeat thousands of times.
When all things have a standard, the variable becomes the powder. And specifically the amount and type you wish to use.

So for my guns, I cast over-sized bullets, but size them to a standard I want to use. (Which is a precision over-size) :veryconfu :lol:

(Incidentally, I have never experienced any signs of over-pressuring using cast boolits. They just aren't as hot as jacketed loads are. No need.)

[RobS]

and will see more of a velocity increase when I go from air cooled WW boolits to water quenched or heat treated WW boolits.

Probably a reason for that related to increased psi.

Larry Gibson

Yep, I'm thinking the same thing.

[fcvan]

I love this site. I get to read the posts of varied opinions and from folks who have vastly more expertise than my own. My education in this complicated hobby really reinforces what knowledge I have obtained through my own experiences. Thanks go out to everyone who shares their collective knowledge and experiences. Frank

[Char-Gar]

A few years back I watched Jim Taylor do a demontration about this issue oversize bullets in barrel and pressure with two Ruger BH revolvers, one in 45 Colt and the other in 44 Magnum. The cylinders were switched and both fired with ammo.

1. A 45 Colt round was fired down a 44 Mag barrel. This is a .452 bullet pushed down a .430 barrel. That is .022 oversize if my head math is right. The bullet stuck the target and Jim ejected the case and handed it to me. It ejected smooth from the cylinder and the primer looked normal in all regards. He explained to me the round has developed max pressure before the bullet hit the barrel and any pressure increase created by the oversize barrel was almost nil.

2. A 44 Mag round was fired down a 45 Colt barrel. It struck the target.

3. The cylinders were then put back where they belonged and a 44 Mag round was fired in a 45 Colt cylinder and barrel. The case expanded to fit the cylinder but the target was still struck.

The target was about 15 yards away, and when we looked at all three holes, they were less than 4 inches apart.

Since that day, I have never put any stock in the notion that shooting bullets a few thousands oversize in a six gun increased pressure in any amount that would any difference to anything.

[onceabull]

Once again,Char-gar, some useful info for emergency use..If some how I find myself sans 45 C.ammo,I will confront the home invader(s) with a cylinder full of 44 Maggies in the OM 45 Blackhawk..only a few spaces inside here where 15 Ft. accuracy won't suffice.!!!! Got to do a dry run soon... Onceabull

[popper]

Thank you Larry. I have evidence of increased pressure from HARD OVERSIZED CBs. When the POI is 2" lower @ 7' and case mouth is dinged because the slide cycled too fast. Wasn't over pressure - cases were fine otherwise, no flattened primer, etc. but much more pressure (velocity). I would be very careful of a hot, heavy, hard, way oversized 9mm load. Not to say it ALWAYS will, but something that does need to be watched. Try pushing a grossly oversized hard CB through a sizer. Sometimes they get stuck. Another possible problem with oversized is the 'fringe' on the base. Like what you see pushing through a sizer, lead from the drive band will leave a fringe ring around the base. I wonder what that does for accuracy and leading. A thin sharp edge that could break off, get gas cut, etc.

[GRid.1569]

Well I shoot "as cast", whatever that is....

I use an 18.5" sizing die (A.K.A. Marlin 1894CS) & 4.6grns of Bullseye to smooth things out...
...and I manage to keep a place in the Scottish National Squad (Gallery Rifle)...

Too small = problem.... a little big, might not chamber (unless you inside neck ream - yes I did that...:roll:).....

If it chambers.. and you're not pushing anywhere near max loads.... go for it.... (with caution...)

[Larry Gibson]

Char, that was a nice "trick" Taylor did but he was both right and he was wrong.

Shooting a 14,000 psi 45 Colt load (SAAMI MAP) in the Ruger (.44) probably did not exceed the 35,000 psi SAAMI MAP for the .44 Magnum. Now what do you think would happen if he fired the same 45 Colt ammo in a .44 Special Colt Model P? Conversely the 44 magnum with the much higher psi was fired in the larger45 Colt barrel, did we really expect to see any higher psi from that? Would have been a more realistic test if Taylor had put the .44 cylinder in a Ruger .41 BH and I'd bet you'ld agree the results would have been quie different.....obviously Taylor was too smart to do that test........

I have measured the time/pressure curve of various 45 Colt and 44 magnum ammunitions. With factory level 45 Colt cartridges loaded with faster burning powder Taylor is correct in that peak pressure is most often reached prior to the bullet entering the barrel. However, Taylor was incorrect about 44 Magnum level loads. The bullets is well within the barrel when peak pressures are reached, especially with the slow powders like BlueDot, AA#9, 2400 and H110.

Larry Gibson

BTW; I do not suggest any of the above exchange of cylinders to fire a cartridge in a revolver/barrel that was not intended for it.......like I said, it was a nice "trick".

[Char-Gar]

The 45 Colt load was a Buffalo Bore "Heavy 45". It contains a 260 grain WFN over enough h110 to give an honest 1,050 fps out of a 5.5" barrel. The round came out of my ammo box and we put some over a crony to keep Tim Sundles honest.

Don't know what the pressure was.

[Larry Gibson]

Haven't tested the Buffalo Bore load but 8.5 gr Unique under Gears 454190 (250 gr) runs 933 fps out of my 5.5" barreled SAA. It runs 16,700 psi BTW (measured in a Contender). The Buffalo load is obviously out of the SAA safety parameters but I would surmise it was relatively mild for the Ruger BH. I'd also guess the H110 load would peak psi wise after the bullet was in the barrel. Do you think it would be wise to shoot the Buffalo 45 colt load in a Colt SAA .44 Special frame/barrel?

Larry Gibson

[swheeler]

I was just discussing this morning with someone the subject of an individual who rechambered an Arisaka to .30-'06 and fired a factory jacketed round in it while measuring the chamber pressure. After the bullet engraved the pressure was actually lower than with the proper ammo in the original chamber. I suspect since more energy was needed to force the grossly oversized bullet into the bore( probably converted to heat), there wasn't enough left to maintain the same pressure level for the remainder of the trip down the bore. Guns do weird things sometimes. Sometimes they blow up for no readily apparent reason, sometimes you can't seem to MAKE them blow up. Same thing with internal combustion engines!

Gear

The Arisaka used a .312 jacketed bullet, the 30/06 uses a .308 jacketed bullet, the .004"smaller diameter bullet should produce less pressure. The bullet is actually grossly undersized, .004" undersized.

So if you RECHAMBERED a 7.7 Jap to 30/06 you would have a 30/06 rifle with a .312" groove, now if you are talking about a 6.5 jap to 06 I don't know what to say about that. I actually witnesses a fellow at the bench next to me , chamber and shoot an 8mm round through an Interarms 30-06, I helped him pound the bolt open.

[softpoint]

I'm thinking...So if ya' smell sumthin' burning, don't panic......Taylor should have worded it that the boolit was already sized down before maximum pressure was reached. Max pressure is reached somewhere in barrel, as the bullet continues to accelerate, but that bullet will be sized down in the throat, where maximum pressure has not been reached yet. ?

[softpoint]

The Arisaka used a .312 jacketed bullet, the 30/06 uses a .308 jacketed bullet, the .004"smaller diameter bullet should produce less pressure. The bullet is actually grossly undersized, .004" undersized.

So if you RECHAMBERED a 7.7 Jap to 30/06 you would have a 30/06 rifle with a .312" groove, now if you are talking about a 6.5 jap to 06 I don't know what to say about that. I actually witnesses a fellow at the bench next to me , chamber and shoot an 8mm round through an Interarms 30-06, I helped him pound the bolt open.

Other factors COULD have a bearing here, the 8mm cartridge is dimensionally different than the '06. Headspace, body taper, brass length, etc.

[softpoint]

Incidentally, Ackley also claimed he took a 30/06 and incrementally increased the headspace, firing after he did so each time, and backed the barrel out where he had to start lengthening the firing pin to make it go off, and only after the entire webbed portion of the case head was out of the chamber did the cartridge head fail and blow off, without harming the gun :shock: Of course, he fired these test rifles remotely. These test would not be something I'd recommend doing on your day off....:coffee:

[Larry Gibson]

Let me say this in the interest of safety since some seem to have a laissez faire attitude toward the subject, now with jacketed bullets;

The harder and larger in diameter the oversized bullet the higher the pressure jump with a given load will be. This applies to cast and jacketed bullets.

As I stated earlier I have conducted numerous tests with various sized cast bullet in numerous calibers with the same load measuring the psi and time/pressure curve for each shot. I have also run the same test with over sized jacketed bullets. Invariably the psi always is higher with the larger sized bullets, cast or jacketed. For example; a recent test with the .308W was conducted. The load with 145 - 154 gr bullets of .308 to .311 was 43 gr of 4895 in LC cases with a WLR primer.

With a .308 Sierra 150 gr SP the MAP was a rather sedate 50,600 psi(M43) with 2717 fps. According to some here it seems that there should have been a sufficient safety factor to substitute a larger diameter bullet with the 12,000 psi remaining before the SAAMI MAP of 62,000 psi was reached. However, it didn't work out that way when a soft steel jacketed 147 gr FMJ of .311 diameter was substituted. The psi for the 2 shots (I quit testing that load) was 73,000+ psi(M43))!!! That was a jump of 23,000+ psi!!!!.

In another post I said with ordinary cast bullet loads in most cartridge/firearms the oversized cast bullet, while still increasing psi, makes little difference, especially when the load is worked up from a lower charge. However, I also stated that problems could arrise in some older, weaker cartridge/firearm combinations from the increase in psi from the use of oversized cast bullets if the loads were top end. I believe there is ample documented pressure measuremets to give justification for the safety caution.

Imagine what the spi's might have been had the .308W control load been at the top end SAAMI MAP of 62,000 psi when I stuck the .311 oversized 147 gr bullet in there? Add +23,000 psi to 62,000 psi and we would have been "over the top" for sure. Oversized bullets, cast and jacketed, do raise psi's, sometimes very drastically. It is not a "myth".

Larry Gibson

[popper]

It is not a "myth". Correct. I'm a relatively new 'newbie' to this stuff. Just like safely working up a load, size and hardness matters. My experience was an as cast (.402ish) pure coated with my home brew poly coating, not sized at all . I didn't think it would be a problem - wrong! 180 TC w/ 4.8 gr 231. Yes, it could be that is was SLOW and POI was 2" low and the slide didn't cycle fully, denting the case mouth, but I don't think so. I read someone wanted to shoot 32 cal jacketed through a 30 cal carbine, thought they would swage down. Maybe? We need to give safe comments so newbies don't have fatal mistakes.

[paul h]

The 45 Colt load was a Buffalo Bore "Heavy 45". It contains a 260 grain WFN over enough h110 to give an honest 1,050 fps out of a 5.5" barrel. The round came out of my ammo box and we put some over a crony to keep Tim Sundles honest.

Don't know what the pressure was.

Interesting, because I would think a 260gr cast loaded with H-110 couldn't possibly be as slow as 1050 fps without being a dangerous underload with H-110. H-110 starting loads with a 260gr bullet are going to be in the 1300fps range. 1050 fps is more along the lines of a top eng unique load.

But back to the bigger dicsussion at hand, unless someone has equipped a gun with pressure measuring equipment, I will take any claims of any load being within SAAMI pressure specs with a huge grain of salt. Just because one load, or a dozen loads don't blow up the gun, doesn't mean they are within pressure specs for the cartridge, for the gun, nor that continued use of those loads won't lead to a catastrhophic failure of the gun.

[Larry Gibson]

"unless someone has equipped a gun with pressure measuring equipment"

I have 25 guns (complete firearms and barrels) of various cartridges so equiped with strain gauges for pressure measurement via an Oehler M43 Personal Ballistics Laboratory.

"Just because one load, or a dozen loads don't blow up the gun, doesn't mean they are within pressure specs for the cartridge, for the gun, nor that continued use of those loads won't lead to a catastrhophic failure of the gun."

I concur whole heartily with that statement based on the pressure measurement of many different milsurp, factory and handloaded cartridges.

Larry Gibson

[Hang Fire]

Oversized cast boolits increasing pressure is another myth I'd love to see destroyed. It's been proven that even .004" increase in boolit size over groove diameter made no measureable increase in chamber pressure.

Gear

Ditto, the oversized boolit will wreck guns is highly over rated.

Take a look here what was pushed through an old break down Brazilian made single shot .410 with intent for destruction of the gun.

http://www.youtube.com/watch?v=wAnbDvLIAac&feature=relmfu

http://www.youtube.com/watch?v=TwX9mJvss1k&feature=relmfu

[btroj]

Wonder if that is non-educated people extrapolating jacketed info to cast?

Imagine that, the concept of misinformation about cast bullets from people who don't shoot them.

[runfiverun]

i think the concept has been taken to legendary status.
"cause my uncle....... [the guy at the shop/walmart/ the range/internet] said so"

[paul h]

Wonder if that is non-educated people extrapolating jacketed info to cast?

Imagine that, the concept of misinformation about cast bullets from people who don't shoot them.

Don't know if having a degree in engineering and practicing as an engineer for 20 years qualifies me for educated or not. Not sure if having turned over 1000#'s ww's into bullets and shooting them through several different revolvers, pistols and rifles qualifies me as someone who has shot cast bullets or not.

I will say that blanket statements can get people into trouble, and a little bit of knowledge can be a dangerous thing. The more I cast and the more I shoot, the more I realize I still have alot to learn. Also the more I realize I should never take the experience with one gun and extrapolate it to every other gun, bullet and powder combination.

Making the blanket statement that oversized bullets will not raise pressures and is totally safe could, however unlikely, lead someone to blowing up a gun. All I'm saying is proceed with caution and knowledge of what you are doing. Those who claim oversize bullets don't raise pressure and who have not backed up those claims by using pressure measuring equipment are speculating at best.

[Northerner]

My Marlin 1895 won't chamber with bullets sized to .459 in anything other than starline brass. It's a pain, but I find that extra .002 thousandths of an inch makes a huge difference in accuracy.

[onceabull]

I'm thinking "Bob's your uncle"------------Onceabull

[BAGTIC]

My Marlin 1895 won't chamber with bullets sized to .459 in anything other than starline brass. It's a pain, but I find that extra .002 thousandths of an inch makes a huge difference in accuracy.

Might be a worthwhile painkiller to have the throat enlarged.

[geargnasher]

......Also the more I realize I should never take the experience with one gun and extrapolate it to every other gun, bullet and powder combination.

Making the blanket statement that oversized bullets will not raise pressures and is totally safe could, however unlikely, lead someone to blowing up a gun. All I'm saying is proceed with caution and knowledge of what you are doing. Those who claim oversize bullets don't raise pressure and who have not backed up those claims by using pressure measuring equipment are speculating at best.

How true, glad you pointed that out. Larry showed the difference in a high-pressure, smallbore rifle, and although small it's measurable, it's still pretty small. The test to which I was referring was a larger caliber at lower overall pressure, and the pressure increase wasn't measurable until after increasing beyond .004" larger than groove diameter.

Anything we change in a load can potentially alter the chamber pressure. Seating depth, case volume, primer brisance, fillers, alloy, etc. A responsible reloader will back off a charge when changing things, and only run the "ragged edge" with carefully selected and verified components (powder lot, case volume, neck clearance, etc.). Not everyone knows or does this, so blanket statements and assumptions can get them into trouble if the tolerances and effects stack just so in the wrong direction.

However, making the blanket statement that a boolit a couple thousandths larger than groove diameter will blow up a gun (which is how I keep hearing it) is pure hogwash.

Gear

[Larry Gibson]

However, making the blanket statement that a boolit a couple thousandths larger than groove diameter will blow up a gun (which is how I keep hearing it) is pure hogwash.

I must have missed that statement/implication............I thought the "myth" was that oversized bullets (cast in this case) wouldn't raise pressures? Damage to a gun or even the shooter or bystanders can easly come well before the "blow up (of) a gun". I think that's the contention here that Becuase psi is most often raised by using larger diameter bullets then there is always a potential for problems.

Just a caution is all from many of us who do think the caution is noteworthy and the statement you originally made is not a myth. We can certainly agree to disagree but the statement was made and then we mentioned the differing opinion and the caution. As usual the reader is left to do as he/she decides.

Larry Gibson

[geargnasher]

Yup, you missed it, it was way back in the beginning.

Gear

[44man]

Care and caution by working loads is still the byword.
I have two boolits nearly identical, same diameter, cast from the same alloy. One has a GC and one a PB. The GC boolit will stick brass well before the PB.

[Larry Gibson]

Yup, you missed it, it was way back in the beginning.

Gear

My apologies but up through your post #7 where you made the "myth" statement and including the OP's original statements/questions I see no mention of "guns blowing up".

You brought the topic of "blowin up guns" in your post #17. Many firearms have been damaged and shooters/bystanders have injured by increases in psi that did not "blow up the gun". That's the whole point; oversize bullets do raise psi's, it is not a "myth" as you claim and damage can happen to firearms and people if the psi is raised too much. It's as simple as that.

No sense continuing with this thread, the point is made.

Larry Gibson

[onceabull]

Looks as though the Arab's board will be the place to look for further reading... Onceabull