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Semi Auto Crimping
lpaalp
Member Posts: 947 ✭✭✭
Recently began tightening the crimp on .45 ACP reloads, meeting the specs in the sticky on the subject.
Ques 1: Does tightening the crimp affect POI, all other factors being the same?
Note: POI on the 1911 appears the same as earlier rounds; tight groups. The Glock, however, showed less accuracy and larger groups than with earlier (looser crimp) rounds.
2) I loaded 150 rounds at one sitting, exactly the same, fired 75 thru a Glock 21, and 75 thru a 1911. The cases of those fired through the Glock are 'smoked' very black around 1/3 of the case and about 2/3 of the length of the case. Those fired thru the 1911 are 'clean' (normal) - not excessively blackened. Memory says the Glock didn't blacken the cases or rounds fired with less crimp (although memory could be flawed; not certain, just didn't notice it with earlier rounds).
Ques 2: Could the tighter crimp cause more blackening in the Glock?
Note: I'm sure the 1911 has a tighter chamber, although I'm unable to measure. One reason I went to a tighter crimp was because of an occasional FTF in the 1911 with the earlier (looser) crimp. (Problem appears to be solved by the tighter crimp.)
Ques 1: Does tightening the crimp affect POI, all other factors being the same?
Note: POI on the 1911 appears the same as earlier rounds; tight groups. The Glock, however, showed less accuracy and larger groups than with earlier (looser crimp) rounds.
2) I loaded 150 rounds at one sitting, exactly the same, fired 75 thru a Glock 21, and 75 thru a 1911. The cases of those fired through the Glock are 'smoked' very black around 1/3 of the case and about 2/3 of the length of the case. Those fired thru the 1911 are 'clean' (normal) - not excessively blackened. Memory says the Glock didn't blacken the cases or rounds fired with less crimp (although memory could be flawed; not certain, just didn't notice it with earlier rounds).
Ques 2: Could the tighter crimp cause more blackening in the Glock?
Note: I'm sure the 1911 has a tighter chamber, although I'm unable to measure. One reason I went to a tighter crimp was because of an occasional FTF in the 1911 with the earlier (looser) crimp. (Problem appears to be solved by the tighter crimp.)
Comments
Crimp can definitely affect accuracy, however.
Why did you tighten the crimps? Was this because of failure-to-feed? If so, did you remove the barrel, blacken a round, drop in barrel, and verify that the case mouth was the hang-up?
Round won't chamber?_"the solution is always the same:
Take the barrel out of the gun. Drop rounds in until you find one that won't chamber. Take that round and "paint" the bullet and case black with Magic Marker or other marker. Drop round in barrel and rotate it back-and-forth. Remove and inspect the round:
1) scratches on bullet--COL is too long
2) scratches on case mouth--insufficient crimp
3) scratches on case at base of bullet--bullet seated crooked due to insufficient case expansion (not case mouth flare) or improper seating stem fit
4) scratches on case just above extractor--case bulge not removed during sizing. May need a bulge buster.
If you want to measure the crimp, then the case mouth should be 0.4739-0.4736".