9mm ammo slug pushed down into cartridge.
- Thread starter Thethickster
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Ok professor gizmo. If the bullet has room to go down and touch the powder then there is no water in between or anything else solid so its going to be empty space where gas will be compressed. You need to look up Boyles law and the compressability of gas. In a shotgun shell the wad goes all the way down against the powder so why doesn't it blow up? The original question was about set back not reloading. Funny there is no mention or training on set back anywhere in military or LEO training. Why is that?
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And what is the +P and +P+ pressure rated?
1KPerDay
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Your point being?
Schwing
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I am, frankly, not sure how to respond to that. Don't get me wrong, I am not trying to argue with you but this should be a very basic understanding of anyone who wants to reload safely. Ammunition pressure curves are extremely important. The analogy that herrwalther used is good but let me take it a step further. I am by no means an expert here so if someone else is, feel free to chime in.
When gun powder ignites, gases expand inside the case. Expansion requires space. If there is no space then pressure inside the case increases. The smaller the open space in the case is, the more rapidly the pressure will spike... This is physics 101. The bullet is pushed out of the case and down the barrel at the point that the pressure exceeds the seal made between the bullet and the casing. Depending on how tight a seal the bullet makes while traveling down the barrel and the length of the barrel, the amount of pressure will either increase or decrease until the bullet is completely ejected. The problem you get into by decreasing the volume of open space in the cartridge is that this pressure spike happens much more rapidly than it should. In most cases (at least in my opinion), you will more than likely end up with a torn casing and a heart attack.) There is the possibility, however, that the rapid pressure spike will continue as the round travels down the barrel and the pressure will exceed the strength of the barrel causing a blow out.
This is one thing I have seen personally at the club where I shoot. I guy came in with some .500s he had reloaded. On about his third or 4th shot, his gun literally exploded in his hands. The carriage and part of the barrel were thrown with so much force that they went through the sheet metal in the roof. He was about the luckiest sucker I have ever seen since he walked away with nothing more but some painful burns and a few stitches on his hands. He later looked though some of his rounds and found that a few of them had been seated way too deeply.
The bottom line is that you might and probably will get away with it but, if you ever have a problem, it can be serious.
beatledog7
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Zeke,
When the same amount of gas (same powder charge, same primer) is released into a smaller volume (due to the more deeply seated and non-compressible bullet taking up more of what would have been compressible air space), the inevitable result is higher pressure, at least until the pressure overcomes cartridge neck tension (and possibly the added resistance of the ogive butting up against the rifling) and available volume begins to increase.
It is during that almost instantaneous building of pressure before the bullet moves that the risk of a pressure spike is greatest. And that instant can be enough to be disastrous.
The shotgun shell doesn't blow up because it has the right amount of powder to release the right amount of gas for the design to function properly. A little too much powder in that same shotgun shell with the same wad depth also produces overpressure due to expanding gas, only this time instead of too little space it's too much gas. The idea is to get the balance right.
When the same amount of gas (same powder charge, same primer) is released into a smaller volume (due to the more deeply seated and non-compressible bullet taking up more of what would have been compressible air space), the inevitable result is higher pressure, at least until the pressure overcomes cartridge neck tension (and possibly the added resistance of the ogive butting up against the rifling) and available volume begins to increase.
It is during that almost instantaneous building of pressure before the bullet moves that the risk of a pressure spike is greatest. And that instant can be enough to be disastrous.
The shotgun shell doesn't blow up because it has the right amount of powder to release the right amount of gas for the design to function properly. A little too much powder in that same shotgun shell with the same wad depth also produces overpressure due to expanding gas, only this time instead of too little space it's too much gas. The idea is to get the balance right.
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The powder reloading book says " could" not "will" and that is leaving them an out in case of any law suits for whatever reason. I could win the lottery! As usual on any of these gun forums we the self proclaimed gun gurus have gotten off topic. The OP was asking about set back and I still call BS on bullet set back being a problem. It is not mentioned or taught in any Military or LEO ( i have had both) training and I still haven't been able to find where it has ever caused a problem. If you do a Google search there is a video or article where a guy purposely was driving bullets in the case deeper and firing them. Not only did he not blow up he noticed no increase in recoil. He was doing this to prove it is BS. If a person is dumb enough to keep jacking and playing with their gun until they are seating a bullet too much then they probably have no business carrying a gun to start with. They sure don't teach you to ease the bolt forward on a M16. Bullet set back, flying saucers, over penetration, all the same. Everybody talks about it but nobody has ever seen it.
I'm that guy. Was shooting .400 Cor-Bons through a G21 and was having problems with nosedives and feedramp-induced jams. Let one get by me and blew up my first G21. Absolutely no doubt in my mind that setback was the cause. However, the setback was exacerbated by the fact that I was using a powder that was too fast for the bullet weight I was loading. I knew exactly what had happened the second I touched it off.
herrwalther
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zeke4351 said:
The water jug was a thought experiment and had nothing to do with actual water inside the case. If you have water inside your ammunition it would probably be safer than higher pressure with bullet setback.
What happens when you put a match to open gun powder not in a confined space? It burns. Gun powder doesn't explode it burns. If pressure were not a concern inside a casing there would be no reason for SAAMI to exist and every centerfire and rimfire cartridge would be shaped like 7.62 Nagant. But in the real world, physics matter. And seating depths of bullets are important.
I know why the military does not teach about bullet setback at basic. Military 5.56NATO have very strong crimps to keep out the elements and a side benefit of being very resistant to setback. 9mm NATO is the same way when using cannelure ammunition. But if you still feel that bullet setback does not increase case pressure, I urge you to get a box of 20 9mm or 40 rounds. Take a hammer and push down the bullet as far as you can and run them through. Hopefully nothing will happen. But will you take the risk?
Unfortunately, you can't prove a negative. However, if you polled every LE organization and military organization that has ever been, every one that is now in existence and every one that will ever come into existence you might be able to prove what you want proven.
It's just far simpler to derive what they DO do and not what they DON'T do. I mean, all the things they don't do would cover a lot of territory. My position is they DO mention it. Of course, as is the usual case, the burden of proof is on the "accuser".
I hope you feel more like you do now than you did when you got here.
Bottom line - if you want quality ammo that will not set back you must learn to reload. The factories only make ammo to sell - they really do not care if it works or even if it damages your gun. They don't have to - they have the finest lawyers that money can buy.
So, I seated bullets way down, using a vise since the normal bullet seater expanded the case and I could not get the round out of the die. For some cartridges, I had to force the round into the chamber for the same reason. No significant signs of high pressure. Recoil normal. No flattened primers. No excessive blast. And I was not killed, in case you were thinking of asking.
There are a number of things that can cause a gun to blow, including an unsupported case, a flaw in the barrel, double powder charge (not hard with a powder like Bullseye), use of the wrong powder, etc., etc. Until there is a real investigation by knowledgeable people, "bullet set-back" is just convenient guess work.
Jim
There are a number of things that can cause a gun to blow, including an unsupported case, a flaw in the barrel, double powder charge (not hard with a powder like Bullseye), use of the wrong powder, etc., etc. Until there is a real investigation by knowledgeable people, "bullet set-back" is just convenient guess work.
Jim
herrwalther
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http://www.hornady.com/store/Critical-Duty
If bullet setback was a non issue, why would bullet companies use cannelured rounds to prevent it? Your one experience with one intentional bullet setback does not negate the experience of others. Setback doesn't cause every firearm to blowup, barrel obstructions probably take first place on that or using +p ammo in a firearm not rated for it. But if you load a 1.13" .45ACP into a well cleaned, and well maintained firearm and it blows up? Might be a bullet setback pressure problem.
Thanks for pointing that out. I will never understand how so many gun owners continue to refer to magazines as "clips".
I'm afraid I've learned the bullet setback lesson myself. My carry gun is a SW1911 and I load with factory (back when you could get them) Hornady XTP's. When I go to the range I shoot ball ammo and unload my SD rounds. Last week after running a couple hundred rounds through I started reloading the magazine with my SD rounds in preparation to leave. I noted that one of the bullets had setback considerably and it kind of gave me the willy's to think that if I hadn't noticed it I could have actually chambered that thing and fired it if and when the unthinkable happened.
Bullet setback is not a joke. True depending upon what the load is you might just get away with it but a +P that has setback no matter the caliber is NOT something that I would want to play crash test dummy with. On the up side, I now have a brand new 45ACP brass that already has the primer in it.
Bullet setback is not a joke. True depending upon what the load is you might just get away with it but a +P that has setback no matter the caliber is NOT something that I would want to play crash test dummy with. On the up side, I now have a brand new 45ACP brass that already has the primer in it.
Fishslayer
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Seating and crimping over a " compressed " load will increase pressure. Set back is not the same, Set back means the bullet is loose enough in the casing that it falls or is pushed back ever so much. It not a crimped " COMPESSED " load. A normal " set back " will not raise pressure ( if anything the pressure will be slightly less ). JMHO and I have a bunch more out in the garage.
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danez71
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