Had a KB! How do YOU properly check case crimp???

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RCMODEL...your phrase "feed ramp cut" is much more accurate than unsupported barrel. I'll take it that unless the brass is expanded (damaged) at the point where there is a feed ramp cut, the expansion of the brass up the case where the brass is thinning (by case design) is normal and not a problem. Reloading those cases should be fine provided the brass is not stretched long or thinner by sizing?
 
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Yes, you should take it as that.

Expansion to fit a loose chamber in front of the case web is perfectly normal.

The sizing die will completely remove it.

PS: You can also see the same expansion on resized brass, if the sizing die is sizing it smaller then spec to start with.

rc
 
Lessons learned? Don't allow interruptions during loading - a good lesson for the entire family!
Multi-stage presses allow mistakes to NOT get caught. Did that case really get sized? Proper powder dropped? Did you mic the bullets to check for proper size? It was a case separation, allowed the head to push back and blow out at feedramp. I've blown the head off a 40 (failed FC case), no harm to me but 'what the heck just happened' experience. Insufficient neck tension will allow set back or bullet jamming in the lands. Either is a pressure overload and with tightgroup, the spread is 0.5 gr min to max(hodgdon 165 gr). That powder is fast and NOT forgiving. Press the nose with your thumb for a seating check. No it's not 20#, but if it is loose, it will move and you FEEL it. It will be loose because the bullet is undersized, the case hasn't been sized or is really thin (or you used a Lee collet die). Couldn't see the headstamp, just looked like a A.
 
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Thanks ... I owned and operated a car forum for 10 years and understand the importance of sharing success AND failure stories ... I can't thank you guys enough and it's the least I can do in return (share my experiences).
 
I'm just wondering why when a thread like this comes up three things are always in the first sentence, KB, Glock and 40 S&W???
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I'm glad I cut my teeth on lower pressure cartridges.
 
ArchAngelCD said:
I'm just wondering why when a thread like this comes up three things are always in the first sentence, KB, Glock and 40 S&W???
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Although KaBooms predate Glocks (plenty of 1911s and other pistol models have KBed before the introduction of Glocks), I think the "stigma" of 40 caliber Glock KBs may have resulted from the popularity of these "Law Enforcement" caliber pistols and greater number of them in use. Simply comparing numbers, there are overwhelming numbers of 40 caliber Glocks being used than other pistols.

IMO, it is only prudent to recognize that KB can happen in any caliber and any pistol (and they have ;)). Do a Google search for "Sig, Beretta, HK, Ruger, etc. Kaboom" and even "1911 KaBoom" and you will find plenty of incidents of non-Glock KBs.

There are several factors that contribute/lead to case failure resulting in a KB. Meet those factors in any caliber/pistol and you will have a KB.
 
Look for pics of rifle case separation, that is what you have. The sizer die is tapered. If it doesn't go ALL the way down or doesn't occur, the case doesn't get squshed enough and the bullet will be loose. Expander and crimper have nothing to do with it. This is a case head separation, the brass flows easily when partially out of battery. Yours wasn't glocked brass. Hot load or loose bullet - probably both. I use the same bullet with hp-38/231 @ 1.110, no problems.
 

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But it's so much fun saying " another Glock KaBoom".;)
I have a couple Beretta .40's and I don't feel their chambers are suported very well.
 
FastCougar,

First of all, I'm glad you still have all 10 fingers.
That must've been quite a shock when it went kaboom!

Thanks for posting this as a reminder to all of us.
No distractions & double & triple check to make sure you have the right charge & the right crimp.

I had a kaboom in my 1911 last fall. The gun was only a month old or so.
Thank God the only thing that happened was a broken grip.
To this day I'm still not sure if it was from a severe setback or a dbl charge.
Never had it happen before or since. (and hope it never happens again)

Please stay safe my friends!
 
Walkalong said:
That is some serious over pressure. Sure, you are getting some bullet setback, but is that enough to do that kind of damage? I dunno, I would lean towards a double charge, plus setback, but who knows.

I have posted here before that if a case is bulged to the point my sizer will not size it, I don't want to use it, even if a push through die (bulge buster) can squeeze it down enough to chamber, because to bulge like that, it has to thin when it does.

I also agree with 918v that a little expansion from pressure is completely different than a bulge from over pressure like in the pic he posted.

Glad you are OK. I hope you get your neck tension solved, and perhaps you may want to try a medium speed powder that fills the case more.
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With TG that much setback is enough to KB. With a more suitable powder that doesn't have an obscenely sharp pressure curve, it is not.
 
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GLOOB said:
I find it telling that with AutoComp, I'm getting crazy signs of overpressure (insane recoil and failures to extract), and I'm still not even getting Glocked brass. No smilies. Not even a lopsided bulge that comes close to what I see on some of my range pickups.

Then with a powder like Titegroup, people are getting kB's out of the blue. (Universal also seems to have a bad rep in this caliber).I wonder if there's any relationship between Glocked brass and kB's, at all. Because it seems like whenever a kB is reported, it just came out of nowhere.
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It doesn't come out of nowhere. Small variations in loads with very fast powders can cause big spikes in pressure.
 
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Just a bit of info from a somewhat new reloader: I read with interest the bit about bathroom scales and pressing to determine neck pressure/crimp or whatever and bullet setback. I drilled a variety of holes in a block of 4x4 with my drill press to hold securely different calibers. Since I had .380 ACP in my press, I checked about a half dozen of varying neck tension/crimp from obviously a bit loose to way beyond to tight.

They all caved in some more, some less, beyond acceptable limits at 30 lbs on my bathroom scale. My guess is a bigger bullet, like the .40 S&W, has more case wall contact increasing friction and amount of force needed to push the bullet back. Not knowing what amount of force is needed for each caliber, I'm inclined to just use case measurements for now until I find more definitive data.
 
Striker Fired said:
For .357Sig I've always gone by 40lbs minimum for holding without setback. That number was derived from some tests done to come up with a lb rating of force imparted on the bullet in an average cycle,slide hammering home from an actual firing,not cycled by hand. To read some on it go to
http://www.handguninfo.com/Archive/www.Pete-357.com/factory.setback.chart.htm
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From the link you provided: "To show you how strong the 357 Sig cartridge really is, as well as how sturdy the Glock 31 is, I test fired a series of cartridges that I "purposely" made with major bullet setback (see charts below).

Glade there are folks with this much confidence to supply data but not my cup of tea.
 
Measuring bullet setback using a bathroom scale is a bit crude.

I measure bullet setback by making a few dummy rounds and running them through my gun. I see about .004" to .006" of setback after ten feeding cycles from the mag. This is the only way to check.
 
Yes it is quite bal**y to test setback and post it . I wouldn't take those numbers and load by them. For the bathroom scale test,I believe it is good,as long as you do double check,as has been said, by repeated cycling of a fair number of rounds to get true measurements. That way you should be able to know if "40lbs" is sufficiant or if you need 45, or 50lbs.
 
You find .006" of setback after 10 trips into the chamber unacceptable?
 
If I was really being pickey about neck tension. I would have a nut welded to my press handle and use a torque wrench to compare your ammo to factory. With the ammount of leverage generated by a press it will probably be best to use one calibrated in inch pounds.
Just a thought for those who really want something more consistant than a bathroom scale. I just press mine on the bench once hard and measure them.
Glad to hear you werent seriously injured.
T
 
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