Bullet set back reminder

[ken45]

How much set back is to much. At what measurement should you shoot up your bullets and at what point should you discard them to the dumpster. Right now I have some .40 s&w HST's that are .006 of an inch shorter then new should I keep them in rotation or shoot them up?
I think if we had a real measurement to watch for it would help.

I believe that 40SW is one of the most risky rounds with setback because the case is small and the pressure is high. A few hundreths of an inch can double the pressure (from 35K to 70k). It's expecially a problem, I believe, with 180grn bullets which sit deeper in the case to start with.

There is a good discussion of this issue at
The Gun Zone -- Glock Model 22 kB!

(The issue is NOT limited to Glocks, although it is seen more frequently with Glocks than with other brands.)

There are also comments and warnings from Glock and Sig about the dangers of rechambering rounds, as well as from ammo manufacturers in other discussions on the site.

"I found that the duty ammo took quite a beating in 6 months. Also just about every ammo manufacturer will tell you that the ammo is only rated for two (2) times through a semi-auto pistol (chambering/extracting), and both Winchester and Federal as recently as two months ago confirmed this again. After two times bullet set-back could start."

Somewhere on The Gun Zone there is a chart with actual setback vs. pressure, but I can't find it at the moment.

Ken

[DefensiveCarry.com]

[RobbW]

Rocky, I didn't realize set back rounds could cause unsafe pressures. Not being a reloader, I never learned that. Thanks for the important info. I had been using multi-chambered rounds as practice ammo.

Every time I take a round out of the chamber I empty the mag, keeping the rounds in order, and put the one from the chamber at the back of the line.

YMMV

Mainspring, I do the same thing. Glad to know I'm not the only one--sometimes I feel a bit too careful (compulsive about it).

[Pete Zaria]

Sorry to kick up an old thread, but...

I was just messing around with my new .45 a bit. I re-chambered the same round 10 times, and checked it with calipers afterwards - sure enough, down to 1.234" from 1.260.
Now, with standard-pressure ammo, I doubt that the slightly reduced case volume would produce high enough pressure to cause a failure - but I won't be shooting that round, that's for sure.

Peace,
Pete Zaria.

[ken45]

Sorry to kick up an old thread, but...

I was just messing around with my new .45 a bit. I re-chambered the same round 10 times, and checked it with calipers afterwards - sure enough, down to 1.234" from 1.260.
Now, with standard-pressure ammo, I doubt that the slightly reduced case volume would produce high enough pressure to cause a failure - but I won't be shooting that round, that's for sure.

Peace,
Pete Zaria.

Pete, good testing and thanks for sharing.

In a .45 which is low pressure (17K IIRC), the risk is a lot less than in a high pressure, "at the limits" round like 40SW. That kind of setback on a 40SW round would be really scary.

The setback you measured on the .45 probably is well within the limits for a +P round (that's just a guess, not a recommendation). But there is no +P for 40SW.

Ken

[Thumper]

The other evening I checked my carry ammo... sure enough, some of the rounds are seated a little bit deeper in the case from being cycled several times.

Time to rotate that batch out to range ammo!

[Tangle]

I avoid this by loading the mag to capacity, then drop one in the tube, then release the slide. Never have any problems doing it this way

DM,
There was a thorough discussion of this loading method here:

http://www.defensivecarry.com/vbulle...pdate-3-a.html

We found that some manufacturers are ok with this, others do not recommend it. I think the manufacturers that are OK with the method is on the last page of the thread.

[edr9x23super]

+1 on mainsprings' post. I do exactly that, and make it a point to shoot the rounds and replace them with fresh loads every 6 months. The old rounds I usually run through a stage in an IDPA match just so I get some realistic practice with defense loads.

To me, it is just the cost of doin' bidness, as we say here in Texas.....