Measuring a crimp?

[Lead Freak]

In order to be consistent, how do you acurately measure a crimp?

[Char-Gar]

You don't measure crimp. If you want to repeat the same crimp on the same caliber, make up a dummy round with bullet and no power and primer. Use this to reset your seating crimp die.

A consistent crimp requires cases to be trimmed to uniform length and have square mouths.

As a general rule, your turn a roll crimp into the groove until you can't snag the case mouth with a fingernail and stop there.

In order to respond further I need to know if you are talking rifle, revolver or autopistol rounds.

[country gent]

Several ways first and easiest is a 1" long ring with a bullet sized hole through it and a chamfer on one end. Se over a case with no crimp and measure then set crimp down to touch and 1/8 turn or less, measure. Once you get the desired crimp make note of this dimension. Draw back is a seperate "ring" for each caliber. Another is to crimp a empty case and measure "crimp" (compressed dia) with calipers or pin gages. You can try measuring the very edge of the case mouth with the calipers knife edges but its hard to get any repeatability or consistency that way. The rings do a great job but are a comparative measurement to use for repeatability. Keep in mind number of loadings case manufacturers dies all can affect this.

[Lead Freak]

I'm loading for both revolver and pistols. I normally use a firm crimp for revolver loads and a slight crimp for my semi-autos.

[Bayou52]

For consistent crimps each time, for pistol and rifle, I've abandoned the seater die crimp in favor of the Lee Factory Crimp Die. Delivers highly consistent crimps with no risk of bulged shoulders in rifle cases.

Bayou52

[9w1911]

I just measure with a caliper.

[troyboy]

Caliper or micrometer. Measure before and after.

[mdi]

I don't have an exact method of measuring a crimp, but if I don't fiddle with the crimp die, all crimps will be the same (I don't think a few thousandths of an inch in case length makes any noticeable difference in crimp, especially in handgun ammo).

[Char-Gar]

I'm loading for both revolver and pistols. I normally use a firm crimp for revolver loads and a slight crimp for my semi-autos.

1. For revolvers roll crimp as I described in my post above and keep a dummy round to reset if needed.

2. For autopistol loading use a taper crimp and not a roll crimp. Taper crimp dies are very easy to adjust, here is how;

A. Place a factory round of 9mm or 45 ACP in the press shell holder and run it to the top of the stroke.
B. Screw the taper crimp die down on top of the loaded round as hard as you can just using your hand and no tools.
C. Set the lock ring of your die.
D. That is if, you are done

I have been at this stuff for well over a half century and have loaded well over a half million rounds of revolver and pistol ammo and have never measured a crimp. Doing so just injects needless numbers, details and complications into an otherwise very simple process.

[twc1964]

Well sai char-gar. I used to measure every auto pistol crimp but now i find that i can adjust by feel and be on the money. Experience is the best teacher. After pulling a lot of misloaded ammo you tend to take a bit more care. Dont ask me how i know this. Lol

[shooter93]

I measure the crimp on taper crimped rounds just to set the die then let it go at that. I have a 10 mm that the diameter of the loaded round at the neck has to be not over the number so I set the die using that diameter,

[catgunguy]

Several ways first and easiest is a 1" long ring with a bullet sized hole through it and a chamfer on one end. Se over a case with no crimp and measure then set crimp down to touch and 1/8 turn or less, measure. Once you get the desired crimp make note of this dimension. Draw back is a seperate "ring" for each caliber. Another is to crimp a empty case and measure "crimp" (compressed dia) with calipers or pin gages. You can try measuring the very edge of the case mouth with the calipers knife edges but its hard to get any repeatability or consistency that way. The rings do a great job but are a comparative measurement to use for repeatability. Keep in mind number of loadings case manufacturers dies all can affect this.

Where could I find one these rings? Thanks.

[country gent]

Most make them themselves, Its a simple piece of rod most use 3/4" round and a caliber + .003-.005 hole bore thru then squared up at 1". An even slicker way would be a Nut 1" across the flats and lay out holes in center of flats and drill thru you could get 6 diffrent aclibers in a nut. I made my own when I was working. Another thing to remember is while size can be measured it is possible to buckle deforem behind a crimp creating other issues. For 22 cal drill a .228 dia hole then chamfer lightly ( about .015-.020 deep) with a counter sink. I would drill around a .200 pilot hole then use the .228 drill at low med speed to "ream" the last little out. The nut held in a vise and the chamfer tool in the chuck turn chuck by hand appling light pressure to depth.