ljnowell
Member
Im not sure what you have "proven" in your tests. If you are saying that brass springback cant occur from overcrimping a round, causing loss of neck tension you are wrong. 100% wrong. Anyone thats reloaded for any amount of time knows this, its readily available information. The fact that you need to overcrimp simply points out that you are either doing something wrong in your reloading or that you have a faulty die.I disagree with you 100%.
When you taper crimp, you're pushing the casing IN to the projectile. That brass has to go somewhere.
45ACP brass is .010 - .013" in thickness depending on brand. When that brass is pushed in to the projectile, the sharp edge of the case mouth forms a corresponding sharp edge in the bullet.
This "ledge" that forms is slight, but it IS there. Moreover, it's provides unidirectional resistance against setback. The bullet can LEAVE the casing because the mass behind the crimp is tapered, and easily pushes the brass out of the way. Conversely, the bullet cannot further ENTER the casing without working much harder, because you've formed a ridge with two sharp edges that mate together.
You can push that sharp edge of the case mouth in .005" to .007" (about half the thickness of the case wall) across the entire diameter of the bullet and still have positive headspacing due to the taper. The bullet can leave with virtually no additional resistance, but it cannot further ENTER the casing without pushing past that ridge.
Because the case wall is (generally) straight, there's a lot of resistance to skip past that ridge formed by the taper crimp.
If you are NOT taper crimping your ammo, regardless of the projectile, or feed angle of the firearm, sooner or later, you're going to run across a piece of overworked, bad, or thin brass and get setback. The steeper the feed angle, the more likely this is to happen. (Case point; Springfield XD. With that severe feed angle it has, I've measured factory Winchester white box before & after chambering and found setback of as much as .007").
And when that happens, if you are unlucky, your gun will look much like the OP's. You shorten the case depth .100 or .200" and you are DRAMATICALLY increasing the pressure of the cartridge if you're loading anywhere near max. How much that pressure ramps up depends on depth and powder type.
When I was working up the loads to those SWC's above, if I did NOT crimp, the Springfield XD would force the bullet deep in to the casing; as much as .250". It would chamber - usually, because as the bullet was pushed back the rear of the casing was being lifted by the slide, eventually shallowing the feed angle enough for the round to enter the chamber.
That's a TON of set back. When I crimped that same load, it would simply stovepipe and stop the chambering of the round in it's tracks, because the bullet couldn't get pushed back in to the casing even with the mass of the slide hammering at it. No setback. No chambering.
WITHOUT the crimp, that Springfield XD WOULD chamber the round, and if I were working with live ammo instead of dummy rounds, and a load anywhere NEAR max, that chamber would be blown to pieces.
Anyway, I'm not going to debate the issue further - you are an adult and can choose what you want to do. It's your hands, and eyes, and face; not mine. You might be lucky and never have a problem.
I'd prefer to have a little ridge form that prevents the bullet from coming back in. The brass itself only offers resistance from sprung tension. The ridge created by taper crimping creates a positive hardpoint of resistance that a bullet has to overcome.
I've PROVEN this already in my own trials. You're welcome to do the same and draw your own conclusions.
Those are facts. Painful as you may find them, they are true. Your overcrimping to compensate for lack of neck tension simply porves that overcrimping the round held the bullet in place. Thats not the purpose of any type of taper crimp on an autoloader round.
You said yourself that the metal of the case gets pushed into the bullet, displacing material. When a round headspaces off the case mouth this is not the proper method of assembling the round. Thats a fact.