crimping .45 rounds

[45pro]

Just to clarify, I think you're mixing up types of crimp. There are two types of crimp, a roll crimp and a taper crimp. Revolvers (as you mentioned above) use a roll crimp to roll the brass into the cannelure of the bullet. This is essential for revolver caliber cartridges.

A taper crimp is not the same - and may be used on any semiautomatic pistol caliber, should the reloader choose to use it. Generally, when a flat bottom bullet is inserted into a straight-walled case, the reloader must flair the mouth of the casing. This is called expansion. When the bullet seating die is used, it pushes the sides of the brass back into the correct dimensions, holding the bullet in and creating more side tension.

But... there are some calibers - 45ACP being one of the most necessary - that use a taper crimp to ensure proper feeding in a tight chamber. 45ACP, 40 S&W and even 9mm all get taper crimps in my opinion, so it ensures that they'll feed in anything. Without a taper crimp, the bullet seating die may not return the brass back to its original size after expansion, and chambering can become an issue. Also, without a taper crimp, cartridges are more prone to shortening after repeated chamberings. It's not that the case was sized improperly, its that force on the bullet during insertion into the chamber can cause it to shorten - even on the first chambering.

Remember, taper crimp and roll crimp are not the same thing. One is for use on bullets with cannelures, and one is for use on bullets without. Over crimping can cause accuracy problems - but non crimping / under crimping can cause feeding issues in picky firearms.

thanks! good information! Rep'd.

 

[Drail]

Any amount or type of crimping will not stop bullets from setting back into the case upon feeding or pulling from inertia in a revolver. Holding the bullet in place is acheived by ensuring that there is sufficient case neck tension. If the case neck tension alone is not holding the bullet stationary then you can crimp all you want and it won't help and in certain cases will actually make the problem even worse. Also cases have cannelures. Bullets have crimp grooves. They are not the same.

 

[mike8170]

Definition for "cannelure":
1. A circumferential groove generally of corrugated appearance cut or impressed into a bullet or cartridge case. The purpose of the cannelure
is to hold the bullet in the case and is used when a roll crimp is applied to the bullet; 2. Sometimes used in reference to an extractor groove.

 

[Jack Ryan]

So i only need to crimp it enough to remove the flare? is .470 too much?

I don't go much by the exact measurement other than to double check what I'm doing against a factory round to be sure it makes sense when I get it "set".

For lead you need a little more flare than loading copper. When I get a bullet seated then I turn on the desk light and hold up a straight edge against the shell. Do the same thing setting up the belling die. You can see it plain as day that way by the light shining between the shell and the straight edge.

I put a factory shell n the press to set up the die to start. Bring up the ram. Back out the seating plunger and screw the die down until it touches the factory shell.

Turn the bullet seater down until it touches the bullet.

Put in a charged case and a bullet to be seated. Mich the case mouth.

Seat the bullet.

Check it all. It will all probably need a little more. Probably didn't crimp at all but check it with the michs and look at it with the straight edge.

I try to just straighten out the case and set the bullet depth.

Check for any high primers.

Load 7 or 8 and fill a magazine.

Cycle them through the weapon operating the slide manually. This is the acid test.

Now recheck all dimensions on the bullets with the michs. If it pushed the bullets in any further, you need more crimp.

If the bullets have any marks on them where they hit the lands or are too long for the mag, you must seat them deaper.

If it squeezed the mouths smaller or changed that or had any problem chambering them, you need more crimp.

Keep your booger hook off the trigger.

Point it at a couple gallon jugs of water if you don't have a safer direction to do this exercise.

 

[Aszerigan]

Any amount or type of crimping will not stop bullets from setting back into the case upon feeding or pulling from inertia in a revolver. Holding the bullet in place is acheived by ensuring that there is sufficient case neck tension. If the case neck tension alone is not holding the bullet stationary then you can crimp all you want and it won't help and in certain cases will actually make the problem even worse. Also cases have cannelures. Bullets have crimp grooves. They are not the same.

Sorry, but this is completely false. Revolver cartridges are roll crimped SPECIFICALLY to reduce pulling from inertia recoil. Period. Holding the bullet in place is a combination of proper neck tension and crimping, which is essential in all revolvers and tube fed rifles. And bullets have cannelures. Lead bullets have grease (or lube grooves) - please make sure you're not confusing the two.

Midsouth HORNADY BULK BULLETS 22 CAL. 224 DIA. 55GR FMJ BOAT TAIL W/ CANNELURE 6,000/ CASE

 

[Drail]

I have never in my life heard anyone refer to a crimping groove on a bullet as a "cannelure". Must be a Hoosier thing. But since you have more little medals on your avatar I guess you're right and I'm misinformed. (just kidding, I don't even know what that stuff means)

 

[Aszerigan]

A cannelure is the technical term - but 'groove' works too. Not a hoosier thing.

 

[Leo]

The term is in the Sierra catalog, so I think it is proper.