Reloading for 450 Bushmaster

[Deleted member 107796]

Hey,
I just got dies for my Ruger American in 450 Bushmaster and had a few questions. I read in the Hornady manual that this round headspaces on the case mouth and heavy crimps should be avoided so that excessive headspace is not created.
Should I avoid or minimize chamfer on the mouth? Can it take a light crimp? I am looking at the Hornady Black rounds I've been shooting and I see a light crimp. I also notice that the fired case length is .007" longer than trim spec and wonder if they compensate slightly long case trim with slight crimp.
With a 16" barrel, I am really impressed at the velocity and accuracy of this beast but it's pretty much a rainbow at 200 yards, with a 250gn Hornady FTX, and minimization of cant is critical.
Thanks for any info you may have.

 

[co_nucleus]

I have loaded some for a bolt action - I don't own a AR platform Bushmaster. I checked headspace with the barrel (not installed yet) and they headspace on the case mouth. I light crimp or they get to much headspace. I treat them like 45 ACP loading and that seems to work. I even played with a 45 ACP taper die rather than a crimp. That seemed to work for the bolt action barrel. It might not work so well for a semi-auto feed.
Sorry - I rambled a bit. This is my limited experience thus far.

 

[J E Custom]

You can adjust the head space with the crimp for your rifle. Take one of the fired cases and try it in your rifle to make sure that the case doesn't make up on the chamber. measure it and if it is a few thousandths long and doesn't prevent bolt closure then you can use it as a gauge for trimming and you can slightly crimp cases this long.

If you don't want to crimp, just size the cases to get .003 or .004 thousandths bullet grip. after trimming to SAMMI specs. Some case growth is normal on straight sided cases.

J E CUSTOM

 

[Deleted member 107796]

Great idea JEC. This reference length should be a fixed distance.
My gun is a bolt also, not semiauto.

 

[Deleted member 107796]

Thanks for the input, guys.
My gun was actually wonking on chambering an empty shell for measurement, so I settled on trimming to saami length of 1.690", chamfered only the interior and applied a light crimp. The range results were very good and I went with 38.2gn Lil Gun.