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Major 9mm average crimp?


TRUbor9

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After you seat the bullet, measure the diameter of the case below the flare. Crimp to within +- .001" of that diameter and call it good.

That is pretty tough to do with a Udie.

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After you seat the bullet, measure the diameter of the case below the flare. Crimp to within +- .001" of that diameter and call it good.

That is pretty tough to do with a Udie.

Not sure what you mean but it shouldn't matter what sizing die you use. Seating the bullet will expand the case to the diameter you need. Measure the case right below the flare where the base of the bullet is.

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I guess I still don't get it. Thats why I don't do a bunch of arithmetic. I just know a pretty good number for 9mm is .376-.377.blush.gif I just adjust for that target and push a few against the bench to make sure they stayed tight.

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I guess I still don't get it. Thats why I don't do a bunch of arithmetic. I just know a pretty good number for 9mm is .376-.377.blush.gif I just adjust for that target and push a few against the bench to make sure they stayed tight.

That's the beauty of this, Sarge. You don't have to do any math. Measure the diameter of the base of the bullet inside the case after seating and before crimping. Adjust your crimp die until you get within .001" of that first measurement. (On jacketed, I usually shoot for the same diameter. For moly, I shoot for +.001" so you don't cut into the cover.) No add this to this and divide by 2.

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Hello: I seat the bullet with the crimp. I then measure down 1/8" from the mouth and write that dimension down. I then measure the case mouth right at the top and make it 0.002" smaller. Different brass has different wall thickness so that is why I do it this way. It works for moly coated as well as jacketed bullets. Hope this helps. Thanks, Eric

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I just take out the bell.... eyeball the deal and call it good. I've prob made 300K that way with never an issue. Then again my gun will run anything...

JT

Same here. I set it by eyeballing till I see very small amount of chamfer on the case mouth.

However, this can be gun-specific. One of my open guns in 38SC required a lot more crimp - haven't seen such a problem with 9mm.

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