Bullet set back ???

A

asleepinTucson

New member
I have been reading a bit about bullet setback and the inherent dangers of re-chambering the same round in a semi auto.

As often as I have to unload my weapon. The gun shops, the gun shows, the ranges.....so on and so on.... What is the safe limit on rechambering a round. It sure doesn't make much sense to replace your chambered round everytime you have to unload your weapon.

Any ideas as to how you all deal with this other than carry a revolver:)

Sleepy
 
I haven't noticed this problem in any of my autos with the exception of the older series Corbon 135gr JHP .40 in a G27. I would get bullet setback after a repeated chamberings. I believe Corbon has since fixed the problem. The last batch of 135gr .40s that I have seen have a cannelure rolled in them to prevent setback.

Still, I routinely change the chambered round once a week and rotate it to the bottom of the magazine. By the time I hit 8 weeks I fire off the magazine as all of the rounds have been chambered before.

If you are concerned about it periodically compare a chambered round with a fresh unchambered round to see if you are getting any setback. Non of my current handgun/ammo combinations seem to have this problem, but I do the weekly change just to be safe.

Good Shooting
RED
 
Some cartridges are more prone to setback than others because of short necks, like the .357 SIG, or low neck tention, like I have found with 10mm Starfire loads from El Dorado. Some guns will cause this problem because of the feed angle.

All you can do is check your ammo and try to limit the number of times you rechamber a round. (If you go into a store while carrying concealed, how will they know if you have a loaded gun if you don't tell them or give yourself away? Think of all the valuable training you have been missing,)
 
why would it be dangerous? will bullet setback cause excessive chamber pressure due to the reduced volume of the casing?
 
why would it be dangerous? will bullet setback cause excessive chamber pressure due to the reduced volume of the casing?"


Yes, I suggest even non-reloaders purchase
a set of dial or digital calipers, much of the
ammo purchased now doesnt have the best
quality control you will find some length
difference in most, a small amount of set
back won't cause a problem in most cases
however again it depends on powder loading.
 
Here's an article about bullet setback leading to overpressure, with numbers:

http://www.greent.com/40Page/ammo/40/180gr.htm

As for commercial loads being susceptible to setback, it depends on the particular load and how much abuse you give it.

Loads with a crimp at the bullet cannelure are much less likely to setback than non-crimped bullets. I pulled a Proload 180gr .40 load and noticed that they machine (?) a ridge into the bullet to prevent setback in this load.

I have also had setback in my Makarovs, shooting commercial Hornady loads. The lacquered Russian Wolf/Barnaul rounds do not set-back as the lacquer prevents it.

-z
 
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