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300blk crimping.
- Thread starter No2sc2
- Start date
Crimping is good for lots of reasons. Besides the setback issue, it promotes consistent starting pressures helping accuracy. I prefer to crimp round that go into semi-autos. The Lee factory crimp die is excellent for crimping. On a bolt gun crimping might not be the answer but for my semi-autos, lever actions, I do it everytime.
How would I know if its a good crimp and a bad crimp? Is a very very very light crimp be enough to prevent set back? Only reason why I want light crimp is to prevent that and I had been doing short COAL but using published data. The published Hornady data don't make sense with their COAL.
That is what is great about the Lee FCD it takes the guess work out, just use it per insturctions provided in with the die.
I followed the directions for medium crimp and they have been fine and staying subsonic. Also using a Lee Factory Crimp die.
Is the instruction "half turn" for light or medium? i tried the half turn and it seemed to get a good crimp on there. So I backed it out and it gave it a light light crimp. I should have put it side by side but I didnt, both of these rounds have the light light crimp.
My bullets have cannelures.
My bullets have cannelures.
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Mine dont have the cannelures, but that is slightly less than the crimp that I use. You should be good. I would venture to say that you need to do a few with a light crimp, then a few with a medium crimp, and see which one gives you the most consistent velocities out of the barrel.
Yeah I didn't want too much crimp because of pressure issue. I'm using 147gr pulls for a 150gr published data. I also didn't use the 150gr recommended COAL as I was following AAC recommendation of shorter COAL for magazine reliability. I also didn't load max charge either. I loaded 10% under minimum charge and did 1 grain increments. I will have to break it down to .5 grains increments to better pin point my barrels performance. I think the most I have is 14 grains for imr4227, H110 and Lil gun. H110 with a short COAL, 14gn and crimp is the only one I'm afraid of pressure issues but I've seen people charge up to like 17 grains. It doesn't mean I still won't have pressure issues since all guns are different.
Those are going to be very light loads. They might or might not cycle properly. It is good to start low and work up, but using 150gr data for a 147gr pill is already putting you behind especially crimping on a cannelure of a 147gr pill, not much but there is a difference. Just be careful when you fire them.
