Crimp?

[obiwankabaldi]

When you reload and set your crimp, how do you know when it is perfect. Don't want my bullets falling out of the case but seem to read a fair amount about too tight a crimp. Is there some secret to this?

[Sarge]

What caliber. I load 9mm. Just crimp enough to remove the bell. Generally, too much crimp can loosen case neck tension.

[G-ManBart]

When you reload and set your crimp, how do you know when it is perfect. Don't want my bullets falling out of the case but seem to read a fair amount about too tight a crimp. Is there some secret to this?

The secret is that crimp doesn't hold the bullet in the case...at least not with cartridges for autos that headspace on the case mouth. Proper resizing and properly sized bullets are what creates the bullet pull (neck tension) to keep the bullets from falling out or setting back.

Part of this is flaring the case mouth just enough to start the bullet without shaving or scratching it. Then, simply remove that bell and make it flat. Add up the bullet diameter plus two times the thickness of the brass at the case mouth and that's the target crimp measurement you should try for. Other than when using particularly thick or thin brass most cartridges have a pretty well known number, for example, it's hard to go wrong using .420" for .40 S&W and 10mm. R,

[redwoods]

I go by the directions that came with the crimp die.

I then take a loaded round and measure it. I then push the nose ob the bullet into a 2x4 or other wood and push my weight against it, using my thumb on the back of the case. I then measure it again. If the bullet moved back into the case, I give it more crimp, if not, I load some up and shoot them. If they shoot well and don't keyhole or tumble, and the accuracy is good, I leave it and load a boatload more.

Randy

[MARKAVELI]

What's the lingo for boatload?

@ Bart I just ordered my setup for .40 & they should be inn tomorrow,and I just measured a few spent pieces of brass and some factory loads the rim on the spent read .425 and the factory loads read 0.421 - 0.422.5 does it very I will be using Hornady HP/XTP 155gr bullet 10mm .400" power pistol with Sm CCI primers!

[High Lord Gomer]

Measurements on spent brass are not particularly meaningfull, as the case has likely expanded some when the round was fired.

I take a slightly different approach to measuring crimp on pistol rounds. I measure the diameter of the case midway of where the bullet is seated. That gives me the full diameter of the bullet and the (double) thickness of the case wall. I then measure right at the mouth of the case and try to have that one to three thousandths less than the full diameter measurement.

.357 Sig I do differently since normal neck tension does not seem to be enough to hold the bullet in place so I crimp that until I can't push the bullet inward.

[MARKAVELI]

Measurements on spent brass are not particularly meaningfull, as the case has likely expanded some when the round was fired.

I take a slightly different approach to measuring crimp on pistol rounds. I measure the diameter of the case midway of where the bullet is seated. That gives me the full diameter of the bullet and the (double) thickness of the case wall. I then measure right at the mouth of the case and try to have that one to three thousandths less than the full diameter measurement.

.357 Sig I do differently since normal neck tension does not seem to be enough to hold the bullet in place so I crimp that until I can't push the bullet inward.

so say I got one completed cartridge(.40) you mean it might measure at .420 but after I seat and crimp I

t should measure .422 cause of the case thickness? Sorry if this seems to be a dumb question! And fed x just dropped my .40 cal kit's!! Yesssssssssssss!

[Corey]

follow the instructions for whatever die you have. Load a test bullet ( no primer/Powder). Measure the length of the dummy round. Either chamber the dummy round inyour gun or push it against your workbench (or both) and measure again. if its the same, you should be good to go. if the new measurement is shorter, you need to adjust the die down for a bit more crimp. then repeat the above process again until you dont get any bullet set back (thats the technical term for the bullet beign pushed back into the case).

I also like to use either a Wilson or Dillon case gage to check the rounds. If the crimp is not proper, it wont pase the gage test.

Good luck!

[Bob DuBois]

I will measure the bulge where the bullet is pushed in the case and subtract .002 to .004. Use that figure to measure crimp at the very edge of the case mouth.

Crimp doesn't hold the bullet it just provides a smooth surface for the bullet to slide into the chamber. The first stage sizing die sizes the brass to hold the bullet.

The 40 round I just picked up measured .422 at the bulge and the crimp at the very edge measured .419 overall length 1.220.

I use a U die on the first station of my 550 and all my brass is range brass pick ups. Try not to crimp anymore than necessary as to much will cause key holing.

If loaded rounds won't drop in your chamber gauge or barrel it's usually not the crimp but the sizing die.

[G-ManBart]

Either chamber the dummy round inyour gun or push it against your workbench (or both) and measure again. if its the same, you should be good to go.

I have seen it where chambering once didn't cause setback, but chambering the round two or three times did cause setback. For that reason I'll usually chamber them a couple of times and measure each time just to be sure...maybe a bit of overkill, but it's not like it takes much time. Normally I just push them against the edge of my bench (hard) as you describe and if that doesn't show setback, they should be fine. R,

[MARKAVELI]

Thanks fellas, so in most cases oal of my crimp is .420! I got a Gage that came with BE's complete setup. And when I measure the crimp using my caliper. Do I use the tip and do I close in on the caliper tight measure? What about when I check the oal of my completed cartridge? Do I measure using the tip or the flat part of the caliper?

[FLSlim]

The push on your bench is a good test. To measure with the calipers, measure as close to to lip of the brass as you can get and use the "knife edge" or tip portion of the calipers, closing them tight. For OAL I use the broader portion of the calipers, although it probably doesn't really matter which you use if you don't push the tip portion into soft lead of the bullet.

[MARKAVELI]

The push on your bench is a good test. To measure with the calipers, measure as close to to lip of the brass as you can get and use the "knife edge" or tip portion of the calipers, closing them tight. For OAL I use the broader portion of the calipers, although it probably doesn't really matter which you use if you don't push the tip portion into soft lead of the bullet.

Thanks slim as long as it touch's the brass and bullet for oal and it touch's with the "knife edge" or tip when measuring the crimp!

[JimmyZip]

I usuall check for set back against my bench with a loaded round and a framing hammer.....

......nah, just kidding.

I do as Bart says, and I do know that sometimes too much crimp can cause setback if the case was belled too much at the powder station. (Or wherever you bell your case.)Just enough to keep the coating on the bullets from shaving, and just enough crimp to match bullet diameter plus 2x the thickness of the case at the mouth. Once that toolhead is set for that caliber, I record it on the box for that toolhead for that specific load, and leave it alone.

[obiwankabaldi]

I usuall check for set back against my bench with a loaded round and a framing hammer.....

......nah, just kidding.

I do as Bart says, and I do know that sometimes too much crimp can cause setback if the case was belled too much at the powder station. (Or wherever you bell your case.)Just enough to keep the coating on the bullets from shaving, and just enough crimp to match bullet diameter plus 2x the thickness of the case at the mouth. Once that toolhead is set for that caliber, I record it on the box for that toolhead for that specific load, and leave it alone.

[obiwankabaldi]

Thanks so much you guys have helped a lot. I did a bunch of bullets (the first ones I ever did just recently)the accuracy and the keyholeing was atrocious. Checking my crimps I see that I am about .417" and I can see where my crimp is rolled into the bullet. I look at factory loads and barely see any crimp. I guess this afternoon I will be pulling bulets. At least I save the cases and primers form this blunder. I loaded 500 and have shot about 100 of those. Thanks again. I will be anxious to see how the next batch turn out.....

[MARKAVELI]

Thanks so much you guys have helped a lot. I did a bunch of bullets (the first ones I ever did just recently)the accuracy and the keyholeing was atrocious. Checking my crimps I see that I am about .417" and I can see where my crimp is rolled into the bullet. I look at factory loads and barely see any crimp. I guess this afternoon I will be pulling bulets. At least I save the cases and primers form this blunder. I loaded 500 and have shot about 100 of those. Thanks again. I will be anxious to see how the next batch turn out.....

What kind of bullet are you using How many grains does you bullets weigh? I too just made a batch of 50 completed cartridge's and I caught the crimping problem my 1st 3 completed rnds, I had em crimped at .417 pulled em and got em and adjusted my crimp to about .419.... Hornady xtp/jp 155gr cci small pp and mixed range brass filled with 7.7 gr of power pistol powder! Went to the range Sat. Tested em, no "key holing" their was some recoil but I was shooting it from a sub compact, my 1st 9 rnds was over 10in my 2nd was about 6 @ about 15 yards guessing! Just wanted to share this with you all!