Glock 29 Kaboom

[The_Shadow]

As is with every cartridge ever developed, there are those that will push till something gives! How much is too much?...OUCH! They are looking for maximum performace throwing caution to the wind.

One thing that comes to mind in the Op's situation, pressure testing if it is done is done so in a fixed barrel fixture. While things may have been within certain limits during that testing, the dymaics of the semiauto pistols can change the way things happen thru out the pressure and ejection phases. Think of bolt action rifle vs. blowback semiautos...

Early unlocking of the barrel and slide, can actually be a cause of case failures, as the early ejection cycle is dragging the cartridge out of the chamber under pressure, increasing unsupported areas. The case expansion could actually work to further increase unsupported conditions pushing itself out of the chamber.

Primers being popped out, can move the slide back from the locked possition, the case maybe forced off the extractor hook, to be left in the chamber.

The question of the aftermarket barrel itself raises some concerns, the angles of the locking lug on the barrel in relation to the angles of the locking block in the frame, could have been different form that of stock arrangements. There is some data to support this on the various Glock gun sales sites, suggesting poor fitting and lock-up situations.

These are a few things that come to mind with the dynamics involved for the Glock and other guns.

The reason I took on this Pull-Down process, was two fold for me, I like to study what lead up to the situation and also to provide better insite, so everyone could learn something from Deadandgone's mishap with his Glock 29. After all it was his intent to post his information for these reasons of having others learn something as well.

[Intercooler]

Is that a pretty acceptable spread?

[DM1906]

Is that a pretty acceptable spread?

Actually, it is, in most situations.  With an average charge of 9.63 grains, we can only assume (as much as I hate to) the target charge was 9.6 grains (conservatively).  The sample group is large enough to make the assumption.  A .4 grain overcharge is 3.84%, which is acceptable in most situations, with the exception of only a few powders (such as W296/H110).  The target charge should allow the overcharge variance (in this case, 3.84%) to never exceed the maximum.  However, this only applies to mid-range and target potential loads.  Full potential loads should be closer to 2% (less than .2 grains, in this case), with a margin of error near the maximum.  This margin should be no less than the extreme of the charges being thrown, with an ample thrown charge sample group.  This also takes into account the published accuracy of most scales, which is normally .1 grains.  The alternative to this is to hand weigh each charge.  Not an easy or practical task when using progressive equipment for the purpose of bulk production.  Velocity is always sacrificed to preserve the safety margin, without exception.

In the case of the load we are discussing, several basic rules were broken, and we see the result.

[The_Shadow]

I would bet Underwood is working to much better tolerances using the IMR800X in his cartridges...

I work to very tight tolerances, hand weighing every round, yes it is a little slower, but the results speak volumes.
Intercooler got to test a few 44 mags I sent him recently with a new cast 260gr HP bullet, I was supprised by his chrony testing of them...
Intercooler test of the  44Mags I sent to him 260 grain Devastators
1436, 1455, 1415, 1456, 1456, 1512, 1457, 1459. Average = 1455.75 FPS/ 1223.20 LBS. Ruger Redhawk 7.5" barrel

When working loads at the upper range of pressure, you just can not afford to have that much fluctuation in powder charges.

[REDLINE]

I would bet Underwood is working to much better tolerances using the IMR800X in his cartridges...

That doesn't seem to be the case with Underwood's 10mm 135gr load, not to mention other Underwood 10mm loads I pulled that weren't as bad but still varied too much in my book.

[The_Shadow]

as a reminder this is 40S&W SwampFox Ammo loaded HOT (too hot) in an aftermarket barrel on a Glock 29, extra power RSA and some other things.

Things that do also come to mind...
Read at CCR raceframes...http://www.ccfraceframes.com/faq-barrels.html

Locking blocks, back a while Carrier had his break. While he was testing some hot loads, did the barrel (aftermarket IIRC) have angles of the lock lug different that led to the locing block breaking? Not known...

Deadandgone started experiencing some issues prior to the KB, did the locking block fail? Did that lead to out-of-battery situation? Early Unlock? Don't know.

[REDLINE]

The variables seem practically infinite.  Kind of scary in a way, or at least enough to keep us on our toes.  Why there aren't more structured guidelines that all manufactuers (gun and ammo and accessory manufactuers) would adhere to is beyond me.  Just seems like it would make sense.  And then there are guidelines that simply aren't followed by some manufactuers.  All in all it leaves a lot of open ground for speculation and all and out question.

[gandog56]

- Don't use stupid hot ammo. If you notice something weird about the ammo, stop using it.
- Some aftermarket barrels cause higher pressure with the same ammo.
- When testing hot ammo, do it one round at a time, with the mag out of the gun.

There's just TOO many people out there that think high velocity is where it's at. I have reloaded for years, and find pretty consistently the hottest loads are RARELY the accurate load. If I hit you between the eyes, what does it matter I missed you with a bullet traveling at warp speed?

[REDLINE]

High velocity is where it's at for me.  I don't care about one hole groups.  Combat accuracy is fine with me.  Hot loads that aren't super accurate from handguns usually don't entirely miss a target unless one should have been using a rifle in the first place.  Just my 2 cents.

[gandog56]

I would bet Underwood is working to much better tolerances using the IMR800X in his cartridges...

I work to very tight tolerances, hand weighing every round, yes it is a little slower, but the results speak volumes.
Intercooler got to test a few 44 mags I sent him recently with a new cast 260gr HP bullet, I was supprised by his chrony testing of them...
Intercooler test of the  44Mags I sent to him 260 grain Devastators
1436, 1455, 1415, 1456, 1456, 1512, 1457, 1459. Average = 1455.75 FPS/ 1223.20 LBS. Ruger Redhawk 7.5" barrel

When working loads at the upper range of pressure, you just can not afford to have that much fluctuation in powder charges.

I just don't seem to be able to justify going that far. What do I care if I'm putting them all in the heart, not just in the right atrium? I don't need to spend hours getting 1 less mm from my groups sizes. And I seem to do alright without worrying. Here is a target, 21 feet using my Precision Bullets 185 grain reloads. I do have a PACT dispensor/scale, so all the charges are supposed to be within like +/- 0.2 grains, but these were with mixed brand cases.