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Old 05-12-2020, 09:25 PM
RDub RDub is offline
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Join Date: Jan 2010
Location: Southern Oregon
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Hey Puritan
You're doing some research.. Good..
I got 1365 fps from 18.0grs N110, so according to them, that's just about right.

Heavy roll crimp;
Your die instructions where it deals with seating and crimping should explain it fairly well.
There really isn't anything that mysterious about it. It just means a substantial crimp. No bullet or case damage should be experienced.

There are two basic methods of crimping. First, the roll crimp, accomplished with your seating die. You are simply forcing the case mouth to fold into the cannalure by a 'lip' in the seating die close to the end of the press stroke. The more you adjust the seating die downward the more force you put on the case mouth. You want to put enough force into the cannalure to secure the bullet tightly, but no too much and damage the bullet. (or the case) There is a 'feel' that you get through experience. If you are seeing 'brass shavings' something is very wrong..

Second method is crimping with the LEE Factory Crimp die, a separate operation. This process crimps the case mouth into the cannalure laterally, from the sides so there is no downward pressure on the case.
This is the method I use mostly.

All we are really accomplishing with crimping is providing just a little resistance or holding back the bullet to ensure a good powder burn. This all happens in a nano second, but our chronographs can see the advantage of crimping revolver cartridges.

Primers and 300-MP. Alliant recommends the Fed 100. The CCI 500 and the Fed primer are very close. I have always achieved very acceptable SD with the CCI500. I've not felt the need to try a mag primer. It is counter intuitive that burning this much 300-MP doesn't require a mag primer, but it really doesn't. 300-MP is not H-110 or 296, it is something different.
You can always experiment with a few different primers.. That's kinda what this is all about.. If you are not getting the accuracy you're looking for, try a different bullet. It can make a difference.

As for AA#9, it is an outstanding powder. Every time I do any accuracy tests where AA#9 is included, it is at the top or is the top performer where accuracy is concerned. I get very good results using the WSP primer.

I hope this helps..

Last edited by RDub; 05-12-2020 at 09:28 PM.
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