Results of Crimp - 38 Spc

New to reloading.  Looking to optimize a 38 Spc load for a M52.  Tested several powders with increasing loads.  Settled on BE at 2.9 gr.  I have a 1:10 twist Clark aftermarket barrel in the M52 and it seemed to group the faster loads better.

Next wanted to test crimp.  Here are the results...

50 Yards - Ransom Rest
2.9 BE, 148 gr Zero WCHB, Starline brass

No crimp - 0.375 - Group size 4.5 inches
Roll crimp - 0.365 - Group size 3.5 inches
Roll crimp - 0.360 - Group size 3.0 inches
Roll crimp - 0.355 - Group size 2.0 inches
Taper crimp - 0.363 - Group size 4.0 inches

I was shocked to see such a dramatic difference just from the crimp.

The 0.355 crimp is the tightest the Lee roll crimp die will go.  I think it will reduce case life from the wear on the case mouth, but the accuracy gain is really good.

Joe

Looks like you found a winner. Did you notice any difference on bullet yaw?

All the holes were round.  I think the installing the 1:10 twist barrel put an end to the bullet tipping.

Nice results. How many rounds in your group?  Thanks.

Interesting. I just loaded 50 rounds with a taper crimp. I had been loading a little proud of the case mouth with a light roll crimp , makes me think about roll crimping.

These are 10 shot groups.

The taper crimp I think could have done better.  The problem was that the taper crimp die I have is not adjustable. I can't make the crimp tighter.  With the roll crimp die I can make is tighter to a point.

I really did not think crimp was such a big factor.  The no crimp rounds would not chamber easily.  So, they were a non-starter and just academic. So, you need at least some crimp, but I would not have guessed that the crimp with cut the group size in half. But clearly it does.

Redding makes one-

Nice! How do you measure roll crimp?

Under a low power microscope, I match my crimps to old Federal Red box wadcutters crimp.
Mine match the performance of those old rounds.
Never have got a grip on measuring crimp.