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Old July 1, 2013, 02:33 PM   #1
Noreaster
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Explain SAAMI pressure and wear on firearms

I found myself looking over my 40 cal pistols and comparing wear marks with my 9mm guns. I checked the SAAMI limits and 9mm & 40 S&W are the same, then I see 9mm +P is higher than 44 magnum, (38,500 vs 36,000.) The 357 Sig, (basically a 40S&W firing a 9mm bullet,) is higher than 10mm. So if I put a 31 barrel in my Gen 3 G22 I will have higher pressures than a G20 shooting a 10mm?What exactly does the SAAMI PSI mean in relation to firearm wear and tear.
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Old July 1, 2013, 06:40 PM   #2
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What exactly does the SAAMI PSI mean in relation to firearm wear and tear.
When your pistol was made, it was made with the SAMMI specs for the caliber it was released in. I assume that the G22 is a 40 S&W caliber pistol. Or rated at 35,000 psi, the gun was setup and timed at that pressure to function properly.

I too played with the 357 Sig conversion on a FNH FNP-40. The 357 Sig is rated at 38,000 psi. I shot maybe 10 rounds out of the gun and decided that while I liked the 357 Sig performance, I was not crazy about how it beat up the pistol. The slide takes more abuse and the frame and fire control group is defiantly shaken up. One thought I had was to change the recoil spring to a heavier one and absorb the additional recoil. Never did get around to it, traded the gun in on a 45 ACP instead.

My basic impression while doing the 357 Sig conversion, was that if I wanted a 357 Sig, I would just go out and buy a gun made for that caliber. And have the correct parts to start with. (and a stronger frame). If I had to do it over, I would start out with a 357 Sig and convert it to 40 S&W. (but why do that?)

But that's just my view on it, others may disagree.
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Old July 1, 2013, 08:32 PM   #3
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Generally speaking, pressure produces very little wear on the handgun, providing it is within the gun's design limits.

What produces wear on guns is recoil. Heavy bullets pushed at high velocity generate more recoil energy, which means slides or breech blocks are slammed to the stops with greater force than with lighter bullets. In revolvers, the inertia of the barrel produces a considerable amount of strain on the gun's frame, plus the slamming effect of the cylinder as it moves under recoil.

In general, most guns are made to withstand recoil for hundreds of thousands of rounds before metal fatigue becomes evident.

The excessive care many give to their handguns is often more detrimental to the gun's life than actual firing.

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Old July 1, 2013, 09:30 PM   #4
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Quote:
What exactly does the SAAMI PSI mean in relation to firearm wear and tear.
Diddly.
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Old July 1, 2013, 10:03 PM   #5
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Awesome. No worries.
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Old July 2, 2013, 02:52 PM   #6
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What exactly does the SAAMI PSI mean in relation to firearm wear and tear.
Not all that much till you get to using overpressure loads or loads near Max. pressure. These will increase wear on the gun.

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Old July 5, 2013, 01:58 AM   #7
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The biggest wear on semi auto handguns is the slide hammering the frame.
The slide does not hammer the frame if the cases land 5 feet from the shooter.

To do that we balance:
1) recoil that moves the hand
2) slide mass times recoil spring force times slide movement distance
3) Forward momentum of the bullet and gas.
4) The force it takes to cock the hammer.
5) Other friction.

If the ammo is too wimpy, the gun will jam.
If the ammo is too hot, the slide hammers the frame.
So in order to assure there will be no jams for a lot of different hands, the ammo is usually too hot.

What to do to reduce wear?
Reduce the handloads or get a stiffer recoil spring.

CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

I have never worn a gun out, but I sure have shot my share of double loads [in overload work ups] that slammed the slide into the frame so hard that my hand hurt for 5 minutes. In some cases triple loads. Those cases eject a long ways. Don't do that.
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Old July 6, 2013, 09:53 PM   #8
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Quote:
Generally speaking, pressure produces very little wear on the handgun, providing it is within the gun's design limits.

What produces wear on guns is recoil. Heavy bullets pushed at high velocity generate more recoil energy, which means slides or breech blocks are slammed to the stops with greater force than with lighter bullets.
Correct.
Quote:
The biggest wear on semi auto handguns is the slide hammering the frame.
Also correct. And the slide impact (except in gas-operated handguns) is the result of recoil.
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Old July 7, 2013, 03:03 AM   #9
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Ok then explain why my 357 Sig is so beat up. High velocity but light 125 grain bullet.
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Old July 7, 2013, 04:21 AM   #10
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Noreaster
what brand of ammo are using?
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Old July 7, 2013, 07:00 AM   #11
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So if I put a 31 barrel in my Gen 3 G22 I will have higher pressures than a G20 shooting a 10mm?What exactly does the SAAMI PSI mean in relation to firearm wear and tear.
You will have to put new springs in I'd say. It's more than just dropping in a barrel
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Old July 7, 2013, 07:58 AM   #12
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You will have to put new springs in I'd say. It's more than just dropping in a barrel
Both Glock and SIG, by design, use the same springs for 357SIG and .40S&W, and in Glocks case, the 9mm as well.

I had a bunch of SIG's in 357SIG, and I also had a .40S&W barrel for each of them. They were just a barrel swap, and there was never any indication there was a problem doing so.

I also had a Glock 31 in 357SIG, and it was beating itself to death from day one, just using 357SIG. The underside of the slide was peening heavily where it was impacting the locking block. I was told this was a common thing with the Glocks in .40, although I only ever saw a couple that showed wear in the same spot, but never saw any that looked like my 31. I was told that like the .40s that had it, the peening would eventually subside and stop, which mine never gave any indication of doing. I picked up a Lone Wolf 9mm barrel for it, and mostly shot that out of it until I got rid of it.

I have a number of Glock 17's, and at this point, one has over 50000 rounds of hot reloads, as well as a couple of thousand rounds of Winchester Ranger T 127 grain +P+, which is more than the 31 had 357SIG through it, and it shows nothing more than some slight "finish" wear in the same spot. It more of a discoloring that it is wear.

As far as pressures go, SAMMI doesnt have a listing for 9mm +P+, but it seems the major makers do have an idea where that is. I contacted Speer on a related issue when I first got into 357SIG, and their response was, 357SIG is a 40000psi round, and the 9mm +P+ is also a 40000psi round, and both would offer similar performance with similar weight bullets.

Now if that is in fact the case, I wonder why my 9mm Glocks seem to have no issue with battering, using ammo in the same pressure range as the 357SIG?
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Old July 7, 2013, 07:56 PM   #13
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Ok then explain why my 357 Sig is so beat up. High velocity but light 125 grain bullet.
Slide velocity (due to recoil/muzzle momentum) is high in the .357SIG. This is the reason Beretta gave for never making a .357SIG version of their 92/96 pistols and for not sanctioning the conversion of the 96 pistols to .357SIG.
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Old July 8, 2013, 03:08 AM   #14
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Winchester Ranger and Speer Gold dot. I have a G33 with a 40S&W barrel and the 357 barrel shows much more wear and some peening. The difference is obvious. I started the post because I was thinking of adding a G31 barrel to my G22. The G22 gen 3 has the older style RSA whereas the G33 has the dual RSA. I was thinking the G22 wouldn't handle the 357 sig as well as the subcompact.
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Old July 8, 2013, 06:05 AM   #15
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Wear

In 50 years experience with the 1911 pistol...about 90% of which was with the soft WW1 and WW2-era USGI pistols...I've never seen a frame that was battered into an unserviceable condition. Ever. A good may of them were badly worn in the rails...but the impact abutments were fine.

A good many frames were cracked at the junction of the rails and impact abutment, but that's neither here nor there. The cracks are the result of thin cross-sections and sharply machined corners. They're self-limiting and don't affect the function of the pistol in any way. I have a pair of early Colt 1991A1s that I've used strictly for beaters. They both cracked at that point many years and many tens of thousands of rounds ago...and they function just fine.

I've seen two slides that cracked in the impact abutments...or the spring tunnel if you prefer...both 1818 "Black Army" Colts. Both of those were well beyond help anyway due to the rear faces of the lugs being so badly deformed that getting even a new barrel to headspace properly would have been impossible.

I've seen a few slides...old and new...that cracked in the breechface area due to recoil forces...but the spring has nothing to do with that.

I've seen barrel upper lugs' front faces deformed to the point of excess headspace. In old pistols this deformation was usually accompanied by matching slide lug deformation. It's rare in new pistols with better barrel steel and heat-treated slides. In these, the bore is generally well-worn out before the deformation and resulting headspace issues can occur.

Locked breech pistols can be fired repeatedly without a "recoil" spring at all...without issue...as long as a FLGR and spring plug is used in the 1911 so as to keep the guide rod parallel to the barrel during the cycle. To date, I've used the same Colt LW Commander to demonstrate this over the years, with a conservatively estimated 500 rounds through the gun without a spring.

Rather than delve into a huge pointless debate that'll turn into a snarkfest as surely as the sun will rise in the east...I'll leave it to the readers to sort it all out.

Cheers, gentlemen. Carry on!
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Old August 5, 2013, 10:12 PM   #16
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Ammo specs can be confusing at times. For instance, the new Federal HST premium defense rounds in 40 cal not listed as +p have similar ratings as Buffalo Bore 40 cal in +p. The difference between velocity and energy is so close you have to wonder which is best (the bullet or the label on the box)!!??!! FBI trainings today are for confrontations at 3-7 yards (Handguns, Up close w/ the FBI). Might be a good idea for us to also train at those distances. It seems that any 40 cal jhp in that 3-7 yard range will do a serious hurt so it probably doesn't matter (see Handgunner, Greg Ellifritz, Is it caliber or equipment). Just find a reliable jhp so the pass thru doesn't wound others, (of course there are no misses since we practice so much under pressure). Cheaper and effective ammo will encourage practice w/ said ammo. Buying 30 dollar box of ammo that won't fill 2 mags means for me, no practicing w/ the good stuff (like wine).
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Buffalo Bore:
Heavy .40 S&W +P Ammo - 180 gr. F.M.J. (1,100 fps/M.E. 484 ft. lbs.)
Heavy .40 S&W +P Ammo - 155 gr. Jacketed Hollow Point(1,300 fps/M.E. 582 ft. lbs.)
Heavy .40 S&W +P Ammo - 180 gr. Jacketed Hollow Point (1,100 fps/M.E. 484 ft. lbs.)
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Federal 40 S&W HST Premium Personal Defense Ammo - 180 gr. Jacketed Hollow Point (1010 fps/M.E. 410 ft. lbs.)

Last edited by bt380; August 6, 2013 at 05:54 PM.
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