Steady Diet of +P Ammo...

[Smitty79]

I've read over and over that a steady diet of +P ammo is tough on pistol life time. If you run nothing but +P self defense rounds though your gun, that makes sense. The muzzle energy is much higher than typical 9mm minor rounds. The frame and slide can take a beating.

I was reading another thread on this forum about alternate powders for 9mm minor. Some people were quoting loads that manufacturer load data showed were into +P. One person didn't think they should be stressing the gun with this steady diet of +P guns.

This sounds wrong to me. I've never had a gun actually break. But I've only run one gun past 10k rounds. Most of the failures I've heard of, that were from wear out non-replaceable parts of the gun, are cracks in the slide or frame. Barrels get "shot out" for high velocity, hard coated rounds (Think Wolf ammo in a stainless barrel AR). If I'm shooting +P loads, that only achieve just above minor PF, the recoil of the gun is low, so the slide and frame aren't over stressed. The velocity out the barrel is the same as it would be so, I'm not going to shoot out the barrel faster.

The one risk, I see, is that the "hoop stress" around the chamber will be higher. Has anyone ever heard of a barrel failing with the fatigue failure that usually "kills" frames, slides or CZ slides stops? I've seen the failure of a double charged 44 magnum. (The guy was shooting "full power" 44 mag loads for Steel Challenge) I suspect the pressure there was something like 2.5X the planned pressure. I've never heard of a fatigue failure of a modern firearm barrel. I suspect the pressure limits are more related to brass failure. The brass is stressed to plastic deformation, hence the need to resize when reloading. I bet the barrels are run below the fatigue limit, though I don't know for sure.

[kneelingatlas]

+P is a marketing ploy and is meaningless to those of use used to pushing the edge 9 major. Look at published specs for +P and +P+ factory ammo, anything over 150PF is pretty rare. I've been shooting 9mm loads 165-175PF and never cracked a slide or frame. The worst was wearing out the locking lug on a one lug compact barrel shooting 9 major.

[Hi-Power Jack]

I'm sure it would depend on the gun ...

Not all guns are made equal ....

Some (1911's and clones) are very tough for a 9mm.

Other makes would probably suffer more rapidly (KelTec's?)

[parisite]

The term....."+P" is actually not very old. Why it came in to being I really don't know. Either a load is over a max charge or it's not.

[IDescribe]

Smitty, in testing the Army found early Beretta M9 pistols could suffer chamber ruptures after somewhere between 10k and 30k rounds (can't remember exactly) as a result of metal fatigue. If I remember correctly, they had three fail. Beretta changed the metal they were making the barrels/chambers from, and all was well. The point, though, is that chambers are subject to fatigue, and if you pound them hard enough and long enough, they can eventually rupture. So it's not just the slide battering itself and the receiver. The chamber, itself, is a concern for over-pressure rounds.

Pistols blow up every weekend around the country. "Squib!" "Double-charge!" But it's most often a guess. No one wants to say "Probably the result of metal fatigue from 10,000 or so overpressure gamer rounds just like 25% of the rest of the rounds out here this afternoon."

[RDA]

The term....."+P" is actually not very old. Why it came in to being I really don't know. Either a load is over a max charge or it's not.

+P is 10% over standard 9mm Luger pressure specified by SAAMI, hence the designation.

[Smitty79]

Smitty, in testing the Army found early Beretta M9 pistols could suffer chamber ruptures after somewhere between 10k and 30k rounds (can't remember exactly) as a result of metal fatigue. If I remember correctly, they had three fail. Beretta changed the metal they were making the barrels/chambers from, and all was well. The point, though, is that chambers are subject to fatigue, and if you pound them hard enough and long enough, they can eventually rupture. So it's not just the slide battering itself and the receiver. The chamber, itself, is a concern for over-pressure rounds.

Pistols blow up every weekend around the country. "Squib!" "Double-charge!" But it's most often a guess. No one wants to say "Probably the result of metal fatigue from 10,000 or so overpressure gamer rounds just like 25% of the rest of the rounds out here this afternoon."

I'm not gaming too much. I'm planning on 9mm minor out of a CZ SP-01 Shadow. I'm not trying to shoot 9mm major.

[twodownzero]

I would gladly shoot 30,000 rounds of +P 9mm through a gun just to prove that it makes no meaningful difference.

Think about it--most .40s are just 9mm frames with a few minor changes. You want to talk about energy?

[IDescribe]

I would gladly shoot 30,000 rounds of +P 9mm through a gun just to prove that it makes no meaningful difference.

Think about it--most .40s are just 9mm frames with a few minor changes. You want to talk about energy?

??? The 'P' in +P stands for pressure. Internal peak pressure is not tied to muzzle energy. You can make loads to game 9mm minor for the lowest recoil possible, let's say 165gr bullets with Nitro100 or N310, and produce very low energy loads that fire with a very high internal peak pressures. Pressure and energy aren't directly related.

[IDescribe]

I'm not gaming too much. I'm planning on 9mm minor out of a CZ SP-01 Shadow. I'm not trying to shoot 9mm major.

Smitty, I know your physics background, and I understand your question. You're correct -- slide velocity is slide velocity, regardless of pressure, so the punishment the slide and receiver take during cycling is not the subject of pressure. +P or not makes no difference when it comes to this sort of wear and tear. BUT that said, that battering you're talking about is not the only wear and tear. There's also fatigue on the chamber. This is where +P can stack up over time.

My previous post referencing the Army's testing was just to illustrate that fatigue can stack up over time and a chamber eventually rupture.

The pistol manufacturers tell us not to feed our pistols a steady diet of +P. But we do. Lots of people in these sports load over SAAMI standard pressures as a rule, some over +P, even in minor PF loadings. Pistols blow up every weekend. But we want to blame it on something else. We call them double charges, but we don't really know. Maybe they're double charges, or maybe those failures are that pistol's overpressure cartridge number 17,348 -- the overpressure round that broke the camel's back.

[peterthefish]

I'm not gaming too much. I'm planning on 9mm minor out of a CZ SP-01 Shadow. I'm not trying to shoot 9mm major.

Smitty, I know your physics background, and I understand your question. You're correct -- slide velocity is slide velocity, regardless of pressure, so the punishment the slide and receiver take during cycling is not the subject of pressure. +P or not makes no difference when it comes to this sort of wear and tear. BUT that said, that battering you're talking about is not the only wear and tear. There's also fatigue on the chamber. This is where +P can stack up over time.

My previous post referencing the Army's testing was just to illustrate that fatigue can stack up over time and a chamber eventually rupture.

The pistol manufacturers tell us not to feed our pistols a steady diet of +P. But we do. Lots of people in these sports load over SAAMI standard pressures as a rule, some over +P, even in minor PF loadings. Pistols blow up every weekend. But we want to blame it on something else. We call them double charges, but we don't really know. Maybe they're double charges, or maybe those failures are that pistol's overpressure cartridge number 17,348 -- the overpressure round that broke the camel's back.

I'm firmly in the camp that believes the warnings to limit use of +P is due to additional wear on the slide and frame as most +P rounds impart more impulse to the slide than standard pressure rounds.

If +P rounds actually stressed the steel in the chamber beyond its elastic limit I assure you that;

A) manufacturers instructions would prohibit use of +P ammo, and

we would see a lot more blown up guns

I'm guessing most popular minor loads with 147s are +P and most competitive shooters put thousands down the barrel.

[twodownzero]

I would gladly shoot 30,000 rounds of +P 9mm through a gun just to prove that it makes no meaningful difference.

Think about it--most .40s are just 9mm frames with a few minor changes. You want to talk about energy?

??? The 'P' in +P stands for pressure. Internal peak pressure is not tied to muzzle energy. You can make loads to game 9mm minor for the lowest recoil possible, let's say 165gr bullets with Nitro100 or N310, and produce very low energy loads that fire with a very high internal peak pressures. Pressure and energy aren't directly related.

That may be, but as stated in other posts that follow yours, it isn't pressure that is wearing guns.

And pressure and energy are directly related, you're just talking about peak pressure vs. average pressure. Where do you think the bullet gets its energy? Force, applied to its area, over the time it spends in the barrel....

[IDescribe]

Twodownzero, I specified peak pressure on the first to uses of 'pressure' but carelessly omitted it the third time, so my bad I guess? If it wasn't clear, I was talking about peak pressure only. Of course, average pressure is directly tied to velocity, and velocity is directly tied to energy. Peak pressure, however, isn't directly tied to energy, but peak pressure is what can stretch metal beyond its elastic limit and rupture a chamber. Peak pressure is also what's described in published load data references to pressure, and peak pressure is what's described by standard and +P pressure ranges. To be clear, peak pressure is what I was discussing.

Peterthefish, many manufacturers do in fact prohibit +P ammo. And many allow for it though advise against using it regularly. 38.5k PSI is the top end of +P for 9mm. 9mm proof rounds are around 45k -- 30% above standard max. I would hope every manufacturer would spec barrels that would handle a steady diet of proof rounds. But I don't know. And the fact that some outright prohibit +P makes me think not. I have seen photos of barrel ruptures, so I know barrel ruptures happen. Don't know what causes them looking at pictures. Double charge? Metal fatigue? I don't know. But that's just it -- I don't know. And I'm not inclined to decide that warnings not to feed steady diets of +P ammo don't apply to me because really it's not about the pressure; it's about slide speed. That's a bet with a costly losing side. I know most get away with it indefinitely, but I suspect that many kabooms blamed on double charges are in fact the gun finally giving in to the abuse.

Also, a correction from something earlier, the Beretta M9 failures I mentioned before were NOT barrel ruptures. They were cracked slides. My bad.

[peterthefish]

And I'm not inclined to decide that warnings not to feed steady diets of +P ammo don't apply to me because really it's not about the pressure; it's about slide speed. That's a bet with a costly losing side.

I'd be much more comfortable feeding any of my 9mm guns a steady diet of +P minor loads than I would a steady diet of 165 PF standard pressure loads.

I know most get away with it indefinitely, but I suspect that many kabooms blamed on double charges are in fact the gun finally giving in to the abuse.

I would disagree.

[9x45]

I was running 125 grain JHP's to 1,280 fps out of one of my G17s. UnderWood advertises 1,300 for their +P+ 124's. After 25,000 rounds it cracked the slide. It still ran but shot like 2 plates to the left on the plate rack. Course I told Glock "Uh, I don't know, it just broke...." Backed the load down to 1,180 fps and it has run ever since then, now at 140,000 rounds.

Edited November 11, 2015 by 9x45

[thermobollocks]

Everything breaks. Run it harder and it breaks sooner. The tiny little nuances in a single instance of even a mass produced gun are going to mean that two different specimens may exhibit different behavior. I've had a 92FS throw small parts in various ways after various round counts. I've seen other guns derp out in fantastic fashion, again, for various reasons.

To 9x45 'cause I can't quote posts for some reason, I've doublecharged a Glock and they still sent me a new one.

[Sarge]

I know most get away with it indefinitely, but I suspect that many kabooms blamed on double charges are in fact the gun finally giving in to the abuse.

I would disagree. Me too. In our game nearly all ammo is home brewed. Some are better brews than others. Not only kabooms but a huge chunk of gun malfunctions are also ammo related.

[9x45]

Don't know about double charged loads, but I case ruptured a G34 15 years ago. Blew out the magazine catch, cut my finger, and wrecked a magazine. It was bullet set back. Out of 300 rounds left, I found 7 that where setback over .100" Pulled and weighed the charge and it was correct. We actually triple charged a BarSto 2nd barrel with TiteGroup and 230 grs and it did not Kaboom, but with the minimum charge weight and .100" setback, KaBoom. I also know that squibs won't KaBoom guns from personal observations at matches. They will bulge the shite out of the barrel though