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Posted: 6/29/2009 10:09:05 PM EDT
| How do u guys assess the perfect crimp? |
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Don't crimp and eliminate the need to assess whether it's perfect.
A "perfect" crimp starts with cases that have identical lengths. After that it's determined by what works for you; if a light crimp or a heavy crimp produces what you're looking for in ammo performance, then that's perfect. |
| I like the crimp that leaves a ruffle imprint on the inside edge of the mouth of the case after firing. That ruffle is imprinted by the ruffle in the cannelure groove. Unfortunately, it is difficult to do. I have crippled many a shoulder trying. Keeping the seating operation and the crimping operation separate, gives you a better chance in getting the crimp like you want it. Seat the bullets in the batch with the die up high enough so the crimp ledge does not engage. Go back and run up the seater stem, and run down the die until the roll crimp ledge engages. Then crimp the batch. As AereE says, you got to start with cases trimmed to identical length. |
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Depends on the cartridge. IMHO ... Roll Crimp. Magnum revolver and tubular magazine rifle loads should have a heavy roll crimp. The case mouth should be firmly pressed into the cannelure. Non-magnum revolver and semi-auto can be lightly roll crimped into the cannelure. For either style the case mouth should be crimped into thebottom-middle of the cannelure, which after crimping will push the case mouth up against the upper cannelure lip. Do not roll crimp on bullets without a cannelure. Taper Crimp. Bullets without a cannelure can be taper crimped when you want them secured for hitting against semi-auto feed ramps and handling multiple/heavy recoils in the magazine (pistol or rifle). The crimp can be done anywhere on the bullet (within reason, just use the listed OAL). It should be a slight pressing in, not a deformation of the jacket. I usually try for pressing the case mouth to 0.005" less than the max width listed for the case mouth in the cartridge diagram. It is especially important on pistol cases to not taper crimp too much. I like it just enough to take out the minor mouth belling for seating, and pressed in just a hair more. On pistol rounds one tip I read on here that I like is to make sure you do not seat the bullet so deep that the case mouth is on the lower edge of the ogive. If you seat and taper crimp so some of the bullet shank is above the case mouth (just a tiny bit is enough1 mm or more) then the ogive can freely slide on the feed rampo and the case mouth edge is less likely to catch on the feed ramp. No Crimp. Most non-magnum, bolt-action rifle, jacketed bullets do not need a crimp at all. the case neck tension of the springy brass is enough to hold it. I think some guys tend to crimp too heavily. If you are buckling cases then you are crimping way too much and need to back way off. Heavy crimping overworks the brass as much as too much case mouth belling and both shorten the life of a case. |
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