This is a discussion on The legend of the Glock 40 caliber kBoom within the Defensive Ammunition & Ballistics forums, part of the Defensive Carry Discussions category; Originally Posted by MattInFla First off, as other posters have noted, there is no .40 S&W +P specification. Anyone manufacturing +P ammo in .40 is ...
There was discussion a few years ago about the same thing happening years ago to the 38 Special. The loads from the 30's and 40's would be considered +P by todays specifications.
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Back before "tort reform" swept through Texas and many other states, I did some product liability defense work for Federal Cartridge. I worked on two cases involving "kabooms", both in Glock 22s. In one case, the barrel split longitudinally through both sides of the the chamber, opening up the top of the chamber at about a 45 deg. angle, and doing substantial additional damage to the gun. The shooter, a female deputy, was uninjured, except for a bruised and slightly burned hand. In discovery, we learned that the gun had a history of use with "reloads of unknown origin," and the raw edges of the split barrel showed both transgranular and intragranular fractures. On the edges where the fractures were intragranular, there was a tiny bit of rust, indicating it had been cracked for some time before letting go. Needless to say, very little was paid on that case, and Glock paid the chump change it took to settle.
In the other case, there was much less gun damage, and it was the more common "fishbelly blowout" where the case ruptured, the barrel remained intact, the mag got blown out and there was a little frame damage. "Injuries" were a little bruising and singeing. Again, there was a history of reload use.
A few things matter here: First, the .40 has a very small case volume and operates at pretty high pressures, even in SAAMI-compliant ammo. A little bit of bullet setback goes a long way, and pressures spike dramatically when it occurs. Significant setback is more common in reloads than in (most) factory ammo, due to various factors. I don't know to what pressure level Buffalo Bore loads its "+P" .40 ammo, and since there is no SAAMI spec for +P .40, it could be most anything beyond SAAMI specs of 35KPsi. Much beyond that, and you're getting into some pretty hot stuff, edging into rifle pressure levels. Setback then will spike pressures even more.
Personally, I have had good results with Buffalo Bore pistol ammo, but I've only used their revolver loads. I also don't mind high pressure pistol cartridges; I carry 9x23s, and they run at around 42KPsi or more, although 9x23 brass has very thick walls and web. I have read reports of .40 ammo with measured, controlled bullet setbacks that didn't seem all that much resulting in pressure spikes to 70KPsi and more. The .40 just doesn't give us much margin of error in that regard, and when coupled with the relatively thin chamber walls of Glock pistol barrels, it just doesn't make sense to take too many chances.
What I was getting at is some manufacturers do not want to have to maintain their setups, enviorment, supplies (powder manufactures, case manufactures, bullet manufactures) to such a tight tolerance, with the associated cost. Instead it makes sense to under design by a safety factor. Some companies, those considered "Premium" manufactures are willing to keep the tolerances tighter and load to closer to max. Others prefer to back down pressures and accept the occasional higher or lower but still in spec load.
Yes, I agree. Furthermore, 180gr bullets leave little room in the case for expansion. A small bit of set back can really cause pressures to surge. I've read one claim that a few hundreds of an inch additional setback can raise the pressures to 70Kpsi.A few things matter here: First, the .40 has a very small case volume and operates at pretty high pressures, even in SAAMI-compliant ammo. A little bit of bullet setback goes a long way, and pressures spike dramatically when it occurs. Significant setback is more common in reloads than in (most) factory ammo, due to various factors.
I consider 40SW to be a caliber with a small safety factor. Couple that with bulging brass (I've seen plenty of that), a high normal pressure, unsupported barrels and you have a combination that is on the edge.
40SW +P? Insane, asking for trouble.
And yes, I've had a case rupture in 40SW, in a new Sig P226 with handloads. It jammed the gun but no other damage. That is one caliber that I will not load any more. YMMV
well guess im not going to be reloading 40s. still gona get a reloading setup but ill load 12 gauge and others, and stick to buying new 40 ammo
I have personally seen a 165 grain Gold Dot have a case head separation in a coworkers G23.
No idea what caused it except maybe setback.