Bullet setback?

[Impureclient]

If bullet set back occures (setback occures from the bullet getting pushed back into the casing from
multi-chamberings) it can raise the chamber pressure to a dangerous level.

Is this statement true? Can you consistently and reliably make a bullet higher pressure by rechambering it?
I was wondering if it was ever tested with a chrono or is this just guessing what probably happens. If it does
at a reliable rate seems you could rechamber a set amount of times (not the dangerous level) and have +P
ammo at no extra premium.

Or is this crazy talk?

 

[Titan6]

Reliably? I suppose if you measured the effects and achieved consistent results you could. But is it true? the other issue would be with an auto for example, having the bullet in the wrong place is not desirable.

If bullet set back occurs it can raise the chamber pressure to a dangerous level.

Absolutely 100%

(setback occurs from the bullet getting pushed back into the casing from multi-chamberings)

Maybe, maybe not. Depends upon the kind of gun and other factors.

 

[rfwobbly]

+1 on T6

 

[The Lone Haranguer]

I was wondering if it was ever tested with a chrono or is this just guessing what probably happens.

A "starter" chronograph can be obtained for a C-note, but only measures velocity, which tells us little. What is needed is pressure measuring equipment, along with a fixture to secure the gun while being fired, remote activation of the trigger, and some kind of containment for safety in case of a barrel burst. Such testing is beyond the scope of the hobbyist gun enthusiast and would need to be done in the facility of an ammo manufacturer or ballistics laboratory. This has probably been done somewhere, but without knowing this, we will have to make an educated guess.

I have fired set-back .45 ACP rounds - on the range only, not for carry - with no ill effects. This has a large case, a relatively light charge of powder (usually) and operates at relatively low pressure. I would not do it with a 9mm or especially a .40, whose bullets take up proportionately more of the case and operate at twice the pressure. The same could be said of many rifle cartridges, where the pressures are even higher, the powder charge is already compressed and further compression could raise the pressure dangerously. I will play it safe and let someone else determine how much bullet setback it takes to blow a gun up.

 

[ReloaderFred]

Where bullet setback really became a problem was in police departments, where the guns were constantly being checked, usually at the beginning of the shift. The procedure was to remove the magazine and eject the chambered round. It was found that if the same round was placed into the magazine and then chambered again, the bullets set back more each time this was done. This caused some really excessive pressures in some cases, especially with high pressure rounds such as 9x19 and .40 S&W.

Yes, there have been numerous tests of this, and it does occur.

As for doing it on purpose to make standard loads into +P loads, then yes, I would consider that crazy talk.

Hope this helps.

Fred

 

[Superlite27]

If it does
at a reliable rate seems you could rechamber a set amount of times (not the dangerous level) and have +P
ammo at no extra premium.

WHOOT!

Nah. In order to reliably get +P loads, it's easier to just put the bullet nose down on a concrete floor and tap it a few times with a tack hammer.

I mean, who would want to do something moronic like check a valid reloading manual and use a press to load a bullet to the specific data in the manual?

Or, even worse: Be an idiot who actually goes to the store and PURCHASES a box of ammo with "+P" marked on it!

What saps!

 

[snuffy]

The theory is that you take a set amount of fuel, ignite it in a certain space, it will yield a given pressure. Then you change one thing; make the space smaller, pressure rises.

A modern firearm is simply a heat engine. The piston of a internal combustion engine and a bullet serve the same purpose. Remember the "hot rods" of the 60's? The technique used to "soup up" an engine was to somehow raise the compression ratio. It gave more powder for the same amount of gas. Seating a bullet deeper in the case with the same amount of powder results in more pressure. Simple law of physics.

We have at our disposal pressure sensing chronographs. It would be a simple task with one of those to progressively seat a bullet deeper in a case with the same powder charge, then watch the pressure rise. What I question is; would it ever result in a blown gun? I doubt I will ever buy the CED millennium pressure test system. It would cost over a thousand bucks, I don't want to know that bad!

WHOOT! what the heck does that mean?

 

[bullseye308]

Can you consistently and reliably make a bullet higher pressure by rechambering it?

Maybe, but why would you want to? You could theoretically push a bunch of bullets in the same distance and theoretically get "consistant" results, but what would be the purpose of doing that? It might be(probably) unsafe depending on the caliber, but again, why? Buying +P ammo would be the wise thing to do if that is what you wanted, and is much safer.

 

[Impureclient]

Thanks for the intelligent replies save the one ***hole reply. I've only been around guns/ammo for all of 4 months now.
I do not reload and I just read that statement on another forum so I was curious.

 

[ReloaderFred]

One of the inherent problems with public forums is that anyone can claim to be anything, and distribute all kinds of bad advice to unknowing persons. I've seen many posts that were outright dangerous in what they told people to do, and I'm sure the posters had never done these acts themselves.

Take what you read on these forums with a grain of salt and always check with known references, usually printed manuals in the case of reloading. Data is thrown around on forums like confetti, and you don't know if the person posting it is drunk when they posted, malicious, or just doesn't know, but thinks they do.

On the other hand, there are people who are more than willing to share their actual experiences with those who are just learning. I count myself in this group. You won't see me posting loading data in most cases, since it's so easy to mis-type, transpose, forget, etc. There are ample loading manuals available in printed form, where all the loads have actually been tested in ballistic labs, so there's no need for me to be throwing what I use into the mix.

Sift through the postings and you'll see things that will help you attain the knowledge you desire. You'll also see some pure tripe, so be sure to look for backup data before you attempt some of these things.

Hope this helps.

Fred