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

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Just a followup to keep all those informed. I have a new screen name as well as a new pet load that I'm now shooting (4gr. TG, Rainier 165gr. RNFP). I also FINALLY got the Glock back from the factory and I think they didn't bother to inspect the barrel ... Check out these two videos and pay attention to the tail end of the first video where I put 14 rounds through the G27 (trigger is factory horrible and it shows in my shooting). 2nd video link (3rd in series about my new load) goes into great detail about what happened at the range with the Glock and why I stopped at 14 rounds ... tell me what you think. Matter of fact, I started a YouTube channel to document everything gun related for me and I plan on doing a weekly video (at minimum) ... please take a second to subscribe to the channel and leave any comments there. Let's go ahead and let this thread die like my poor Glock frame ;)

http://www.youtube.com/watch?v=_oK11iRjyqM

http://www.youtube.com/watch?v=_Vz1w2hqj6U
 
I think the crimp for these type cartridges is probably one of the most mis-understood elements of reloading. The crimp for these type cartridges, being those that head space at the mouth, is not intended to produce or even increase necessary neck tension.

From what it sounds like to me you applied to much crimp which reduced the diameter of the case mouth so much, that the mouth became pinched in the throat when it was chambered and fired. A pinched mouth will certainly increase pressures enough to KB most any firearm. Imagine what happens when the bullet is delayed by just a fraction of a second from exiting the mouth? KB

A suggestion I think more new reloaders should consider, is to pick up your reloading books and read them to the extent that you understand the difference between various cartridge designs and how these differences apply to reloading. On the flip side, a case that head spaces on the rim is reliant on a firm crimp to prevent bullet set back or jump. Read your reloading books. Your fingers, eyes, guns, and lives depend on it.
 
I just read about 100 posts on this thread and have had enough.

Anyway, I don't understand why a reloader would reload for a glock 40 cal with a unsupported chamber or even use brass that had been shot out of one. It just doesn't make good sense IMO.

My .02 cents would be if you have to have a glock and want to reload for it replace the barrel and reload ONLY brass you know hasn't been shot out of a glock
 
It ok to reload for a Glock .40,plus use brass shot out of a Glock(or other brand that are not fully supported)as long as reasonable judgements are used and followed as far as how "hot" to load them,or how much of a "bulge" is too much to resize.It is all in the hands of the person doing the reloading and what chances they feel are safe.
I myself,just don't care for max or even near max loadings,unless for certain circumstances. That way there is more room for variances.
 
nobody said anything about what the brass was trimmed to or did i miss that part. all that sizing and debulge had to increase the length somewhat. just a thought if too long and too much crimp that would sure put some brass in the barrel.
 
The .40 S&W headspaces off the mouth,so it wouldn't matter if the brass was 1/2" too long,it still wouldn't put the case any further in down the throat than a correct spec case.
 
for a jacketed bullet ... plated bullets should be loaded with lead cast bullet data, at least that's what Rainier suggests. The recommend starting at the mid point and adjusting accordingly. As for plinking or target loads, you can go as low as will cycle the slide reliably and going hotter proves nothing other than the laws of physics.

As I stated in the latest video at the end, I plan on adjusting the charge .1 grain lower for a few shots, then keep doing so until I hit that point with the M&P (won't cycle reliably). I'm retiring the Glock's barrel in exchange for a 9mm conversion barrel, but before doing that, I plan on getting a Chronograph to see just how slow this pet load is.
 
I've always wondered if the bullet setback KB thing has something to do with the powder being used. I'd be curious to see a pressures measured for 40 S&W with various COAL (simulating setbacks) and various powders. My guess is that we'd find that some powders are much more sensitive to setback. Anybody ever heard of a 40 S&W Kb with Unique?
 
I'd say the 40 S&W is one of the worst rounds for bullet setback. Especially if you are loading mid to upper level pressures. There ain't much room left in the case, so if the bullet gets pushed back in, pressure skyrockets. 9mm is the same way.

Neck tension is critical. Crimp doesn't improve neck tension. In fact, in the case of lead bullets, it usually reduces it.

The 3rd gen Glock barrels have as much case head support as a Lone Wolf replacement barrel. Or at least they are really darn close. I know that surprised me when I had the two sitting side by side on my bench.
 
Check the size of the expander.

Removing a few thousandths of an inch may well increase case tension enough.

The case ID should be at LEAST 0.002 inches SMALLER than the bullet OD.

The case tension is created by forcing the larger OD bullet into the brass case.
 
What RC said!! Use a slower burning powder and you'll greatly reduce the possibility of over charge or bullet set back causing enough pressure spike to KB.

And regarding crimp, only crimp to the extent that you have returned the mouth back to it's near starting diameter or you will teater on pinching the bullet in the throat!
 
Is it realistically possible to have excessive neck tension?

My .40 loads use a 180 grain Hornady FMJ and 6.4-6.5 grains of Power Pistol.

I made a few dummies and measured the OD of the case body before loading the bullet, and after, and in all cases it expanded 0.002 of an inch. I put what I think is a light taper crimp on the dummies--I crimped until the OD of the case mouth was about half-a-thou smaller than the case body. I aimed for an OAL of 1.125 and this ammo functions perfcetly in Glock 23.

With all that explanation out of the way, I rechambered one dummy over and over again, holding the slide all the way to the rear before letting go completely. I repeated this Forty (40) times and the OAL had only shortened by 0.002 of an inch?

Sound acceptable? The Hornady FMJs have an additional angle compared to a hollow point, and I hypothesize that it limits setback because all along the "extra" angle connecting the ogive to the meplat the bullet has what I would call in metal finishes "hammer beaten" appearance after forty chamberings.
 
Load Data:

Case: Federal (once fired - bought rounds and fired myself)
Primer: CCI 500
Powder: 4.9 grains of Titegroup
Bullet: Rainier 165 grain HP

Video description explains exactly what happened. Over bell removed all neck tension as the die wasn't a under-sizing die. Over crimp turned the mouth inward, impeding the barrel throat as well as causing setback ... pressure had only one way to go before it could overcome the resistance. Round landed on target lower left @ 7-8 o'clock position.
 
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