Ka-Boom

[BrokenolMarine]

Reading through the reloading threads this morning, I was reading one titled "Maximum Safe Pressures." The thread posed a great question and the answers provided great advice. I didn't see one issue addressed that lurks in the shadows to bite us if we let it. it can cause serious over pressure issues and even the dreaded Ka-Boom... but can be avoided.

BULLET SETBACK.

This can be caused by several factors.
A double feed in a semi-auto.
Heavy recoil in a tubular mag firearm.
A jam on the feed ramp when feeding.

The main contributing factor in every case is a weak crimp. When the bullet gets set back in the case it creates a compressed load, like the piston in a cylinder. If you experience a jam, you may want to put that round aside rather than top off the mag with it and go back to shooting.

Am I qualified to comment? The phrase been there and done that applies.

Years ago... way back when I was young and just starting.... ....

I had just gotten a new progressive, gotten a quick lesson or two with 38 wadcutters, then switched over to .45. Trying out a new Glock 30 .45 caliber everything was going fine until I had a double feed. I cleared the malfunction, loaded both rounds back into the mag, and KA-BOOM.

Lots of things happened at once.
The magazine blew out of the bottom of the gun as the pressure swelled the grips.
The mag release left, never to be found.
The slide locked on the swollen frame.
Blast struck me in the face, cutting me only above my shooting glasses.
The blast bruised my hand, but broke nothing.

My shooting glasses looked sand blasted, but saved my vision.
I sent the company a thank you letter. They forwarded a copy to every employee with their paychecks.

My mentors came over to diagnose the issue and checked my loads. No double loads, the press appeared to be set up correctly for 45? But wait... This crimp is a bit too light and didn't you say you had a double feed... ?

One of them explained the problem, which is where I learned about compressed loads.

I sent the gun to Glock for the engineers to examine as a courtesy. I was shooting handloads for competition practice. As a Glock armorer, and LE Instructor I knew it wasn't a warranty issue, but they wanted a peek. They replaced the gun at cost. I was happy to pay it.

My lesson learned?

Check my crimp settings.
I never fire jammed rounds, the risk isn't worth it. (I might salvage the bullet )
Check my powder drops periodically thru the runs, just in case.

[RanchRoper]

Wow. Thks.

[clovishound]

Obviously the issue was you fired it in a Glock.

Seriously, setback can be a real problem. It is something we worry about with our tube loaders, but not so much our bottom feeders. And yes we should consider it. Particularly in weapons with unsupported chambers.

[BrokenolMarine]

Very Funny Clovis. Actually, the two mentors who came over after the fact were both senior Police Sergeants who ran Metro Police ranges. Both said I was lucky the KB occurred in the Glock Platform. (Yeah, Lucky, I said. Cocky youngster that I was at the time.) Seriously... said one of the Rabbis. (Rabbi, in the LE sense of the word... although, come to think of it, he IS Jewish... LOL )

"In something like a 1911, the pressure would have blown both the grip panels off the sides of the frame and you'd likely have some broken fingers." Said Rabbi #1

"Yup, Lucky" Said Rabbi #2 nodding in agreement, while he was looking thru my Reloading setup, tweeking here and moving things around. I was annoyed, but with 60 years experience, or more, between them. I didn't complain and later found that the adjustments made things much easier. (Sigh)

I always try to shoot with those who know more than I do, and I always find that there is always someone who does. LOL.

jim

[JEBar]

this is the reason I am very concerned about Hornady 45-70 Lever Revolution brass .... their bullet requires the brass to be cut shorter than standard 45-70 brass .... this means that reloading them with standard bullets and crimping them at the crimp ring on the bullet seats the bullet deeper in the casing .... I don't know that the difference is sufficient to create a safety issue but I will not test it in our rifle

[tractortad]

Did not know that improper bullet setback could do this.....Thanks for sharing.

[tx gunrunner]

If your gun stop working check it out 1st before continuing . Don't keep trying to shooting it you could blows up . . He ejected a round that didn't fire . Never checked barrel or brass leaving the bullet in barrel and putting a fresh round in gun and fired it . If you have squib load did you not forgot to put the correct charge in the cartridge or did you double charge another round by mistake .

https://www.youtube.com/watch?v=Oh1lyMyejpI

[BrokenolMarine]

As an instructor, I always try to share my mistakes, even if they make me look a bit silly, so others can benefit from MY lessons learned and avoid the somewhat costly errors. Sometimes they learn and avoid them, but sometimes... they have to make the same mistakes before they learn.

As parents we see this.

"The Wood Stove is HOT don't touch it."

Psssssst

"Owwww"

"Burns doesn't it.?"

[tx gunrunner]

Did not know that improper bullet setback could do this.....Thanks for sharing.

A lot of pistol ammo like the 40SW work on 35,000 plus PSI and a .010 bullet set back can make the pressure jump to over 50,000 psi . The early Glocks and other gun had unsupported chambers for a 100% feed and the brass let go there if the psi is too high . The bottom pic #3 shows unsupported brass that blow up .

[CT_Shooter]

As an instructor, I always try to share my mistakes, even if they make me look a bit silly, so others can benefit from MY lessons learned and avoid the somewhat costly errors. Sometimes they learn and avoid them, but sometimes... they have to make the same mistakes before they learn.

It's honesty like yours that makes this forum what it is. Thanks for sharing it, Marine.