Might be time to check your chambered round.

[jpshaw]

With the scarcity plus the increased price of ammo we are all shooting less. Just today it had been so long that I was going to shoot one mag of my precious stash of 9mm. On dechambering the carry round it looked shorter so I checked it side by side with a new round. It had experienced some set-back. Needless to say it got sent down range with the FMJ stuff. I used to check for set-back fairly often but lately I've been just rechambering the same round after each cleaning and not looking at it. I need to pay attention more.

[muggsy]

If you found the round set back and knew that it was a dangerous condition why did you shoot it?

[jpshaw]

Oh, I will shoot a set-back round sometimes. It depends on the amount of set=back I see. Just a touch it gets shot but a bunch it gets tossed. If you check them often you can catch them early. Had a .30-30 set back on me last season that I tossed.

The biggest problem with set back is that it is evident that the bullet has moved inward from its original "crimped" position. Once it's moved a little it will be easier for it to move more. The reason most bullet are seated to the position they are in is to achieve a certain OAL to aid in function in a repeating action. Or in the case of my single shot rifle, for the bullet to be within about 1/10" from the rifling. A certain amount of backward movement doesn't necessarily mean that pressure will be at a dangerous level but it does mean that it is headed in that direction. If it moves either toss it or if you determine it's still in a pressure safe area, shoot it, just don't keep it.

[Bawanna]

I do that too. A little bit gets shot, a lot gets tossed.

[jocko]

I very seldom even unload my PMJ9. No kids around at all, ..

[lamppa]

I've got kids around and I keep my loaded cm9 in my nightstand drawer.
If my wife hurt her hand trying to rack the slide, you think the 9 and 3 year old girls can chamber a round? I think not.

Sent from my DROID4 using Tapatalk 2

[AIRret]

I do that too. A little bit gets shot, a lot gets tossed.

Absolutely!!
Plus, if the chambered round still looks good I still load it first (which means it's in the bottom of the mag).

[Cole125]

With my carry guns, a round only goes into the chamber once. It's carried with that round until I go shooting and it gets shot.

One trip down the chute for my SD carry ammo.

[wyntrout]

I use pliers to break them down, shoot the primer, and burn the powder. I made a video, too, the last time.

Wynn:)

[jpshaw]

Absolutely!!
Plus, if the chambered round still looks good I still load it first (which means it's in the bottom of the mag).

However, if you ever have any set-back do not put it in the mag at all. It now has a shorter OAL and could prove unreliable. If I had to carry a set-back round it would be in the chamber. I understand what you're saying though. "A previously chambered round moves to the bottom."

[muggsy]

Oh, I will shoot a set-back round sometimes. It depends on the amount of set=back I see. Just a touch it gets shot but a bunch it gets tossed. If you check them often you can catch them early. Had a .30-30 set back on me last season that I tossed.

The biggest problem with set back is that it is evident that the bullet has moved inward from its original "crimped" position. Once it's moved a little it will be easier for it to move more. The reason most bullet are seated to the position they are in is to achieve a certain OAL to aid in function in a repeating action. Or in the case of my single shot rifle, for the bullet to be within about 1/10" from the rifling. A certain amount of backward movement doesn't necessarily mean that pressure will be at a dangerous level but it does mean that it is headed in that direction. If it moves either toss it or if you determine it's still in a pressure safe area, shoot it, just don't keep it.

So how much set back is too, much set back? Where do you draw the line?
.010, .020, .050? A curious mind wants to know. No one seems to be able to give me a definitive answer. I guess it all depends on how much you value your gun and various body parts.

[muggsy]

Bullets for the 9mm range in weight from 110 grains to 147 grains. Since they can't make a 9mm bullet any larger in diameter and still have it fit in the case the heavier bullets must be longer in length. If you seat both the 110 gr. and 147 gr. bullets to the same max. OAL the longer bullet must be deeper into the case. Does that make the 147 gr. bullet more susceptible to the dangers of bullet set back? From what I can determine there are no definitive guidelines. My policy has always been, when in doubt, don't shoot. And I still have most of my body parts. :)

[muggsy]

Being a man with a curious mind I decided to go to the experts for advice. Below is a link to SAMMI. Most reloading manuals give you the maximum OAL of a bullet but very few if any give you the minimum OAL. According to SAMMI the max OAL for the 9MM Luger is 1.169. The minimum OAL is 1.000. Even I had no difficulty in determining that's a difference of .169 in OAL. So once again I ask, how much set back is too much set back?

http://www.saami.org/specifications_and_information/publications/download/205.pdf

[MW surveyor]

There are a number of factors that you need to get the proper response of how much is too much. Biggest one is the type/brand of powder. With powders that are available to the general public, this is pretty easy to determine by plugging in the powder, bullet weight and OAL. Not so with commercial rounds. You can get the bullet weight and determine the OAL but the ammo manufacture will probably use a propitiatory powder or blend which they will not tell you.

[jpshaw]

The range of AOL is more then you know. If you look at a round and can say "Wow, that round it set back" then toss it. After I chamber a round a few times I put it on a flat surface with a new round from the same box and compare them from the side. If it's shorter then the new one but otherwise looks like a normal bullet it is set back and shouldn't be part of your mag or in the barrel but unless it's a +P+ the pressure should be well under the 35,000 and I will send it downrange. Once a bullet moves from it's normal crimped position it is no longer to be trusted as a carry round since it can move deeper into the case now with very little pressure.

[muggsy]

I've heard of the dangers of bullet setback since I first started reloading back in the late '70's, but I never seen a catastrophic failure of a firearm due to it. Every time I've heard of a catastrophic failure it was the result of a failure of the person doing the reloading. Double charges of powder, using the wrong powder, etc. I've yet to see one case where of bullet set back was proven to be the cause of the failure. I'm not saying that it can't happen. I'm just saying that I haven't seen it. I have a tendency to err on the side of caution. If I see that a bullet has set back more than .025 I won't fire it. That's where I draw the line. I'll pull the bullet, resize the case, refill the powder and reseat the projectile. Then it's good to go.

[Kong]

Maybe a dumb question, but, does this apply to all ammo, or just reloads?

[MW surveyor]

Maybe a dumb question, but, does this apply to all ammo, or just reloads?

Applies to all ammo used in a semi-auto that has been chambered a number of times.

FYI - Just to confuse you a bit.......Revolver ammo in the cylinder can get bullet creep (longer) when firing unless tightly crimped.

[Kong]

Hmmm... Ok thanks for the info!