I've posted these results several times in the past several years,
it serves to quite clearly show that the crimp has little to do with consistent ignition. One thing all five of these tests have in common is consistent neck tension. Some are carbide die sized, some are not sized at all. Some have a roll crimp, some have a profile crimp and some are not crimped at all. 44man was right, straight wall handgun ammo accuracy is all about consistent neck tension. That means brass fired the same number of times and not so many times the brass has lost it's elasticity, all sized identically.
Crimp Tests
FA 357 Mag 9”
RCBS 180 GC Silhouette @ 192 gr. (WW +2% Sn HT @ 18 BHN)
16.0 gr. H-110
Winchester brass
CCI 550 primer
Temp 70 Humidity 38%
January 29, 2008
All chrono tests 10 shots
1> My normal profile crimp, second firing of WW brass, Carbide die sized
E.S. 30
A.V. 1518
S.D. 9
2> Roll crimp, second firing of WW brass, Carbide die sized
E.S. 30
A.V. 1520
S.D. 9
3> No crimp, second firing of WW brass, Carbide die sized, very slight bell
E.S. 30
A.V. 1528
S.D. 9
4> Light profile crimp, virgin WW brass, not sized, not expanded, slight bell only
E.S. 26
A.V. 1532
S.D. 8
5> My normal profile crimp, virgin WW brass, not sized, not expanded, slight bell only
E.S. 26
A.V. 1536
S.D. 8