Bullet Set-Back; Why Some Guns Go Kaboom

[Graves]

Squibs suck, be careful.

[SA Friday]

No I haven't tried to fire one. A round stuck half way down your barrel is no big deal. Squibs happen all the time. Just take a squib rod and small hammer The only time a squib sucks is when you don't catch it. Thinking if I have any type of experimented round in the gun, I'm checking the bore every round.

[Irving]

Yeah, that's exactly what I was thinking. Only load one round at a time and check the barrel each time. How long am I supposed to soak the round in bleach to kill the primer? I want to try some tests.

[SA Friday]

My last batch I soaked, I just put them in bleach water overnight. If it hasn't soaked through by then, it never will.

BTW, doubt this will work on ammo that's been sealed like Wolf with the sred stuff around the bullet and primer.

[SSChameleon]

SA, this is good stuff. Thanks for the in depth post. I think we need to write Mythbusters and get them to see how much setback it takes to KB a gun. They can test the bleach idea while they're at it.

[SA Friday]

Ya, I really need to test that. Ironically, over the next three years I'll be taking a butt load of chemistry classes. I think I'm going to wait until I'm edujmakated a bit more to expand on that one.

Mythbusters might do it. Give it a shot.

[smchop]

So, was .40 the only round you tested? After reading this post the other night I decided to check my carry gun. It is a springfield xd sub 9mm, I've had the same federal rounds in there for pretty close to a year now and usually unchamber when I get home. Never having thought about setback till I started reloading myself I decided to check my ammunition in my mag and have zero difference in OAL. Nothing changed on my firearm from factory build, so stock springs etc. Is it just because 9mm springs are that much "softer" than .40 cal springs?

[SA Friday]

Depending on the gun, many 9mm and 40 cal models have the exact same OEM recoil spring in them. The XD sub-compact 9mm and 40 cal's are one of these.

The reason you haven't seen any set-back is probably because the 9mmx19 case isn't a straight wall case. It's larger at the base than it is at the neck. This helps retain the bullet in place a bit better IMO over a straight walled case. You get a bit more bite from the inside edge of the case mouth. Although I don't have the smarties to figure it out, I think the smaller the bullet the tighter the case mouth can retain it. I could be wrong on this, but it seems I have more problems with 45 ACP and 40 S&W over 9mm and the smaller calibers. (Side note: I use a U die when I reload 9mm and 45 ACP too.)

Manufacturer plays into this too. I have 45 ACP rounds that I've pounded on and no movement. Federal Hydro-shock bullets with nickle plated cases have a retaining ring in the middle of the case below the bottom of the seated bullet. When the ring gives, that bullet seats itself until the powder is compressed. Great defensive round, but you don't want to rechamber it very often.