.300 Win Mag

[AR15DCM]

Going to start reloading the 300 WM and I've never reloaded a belted cartridge before. Are there any special considerations when reloading this round? I have plenty of experience with .308, .243, etc etc...

Thanks,

 

[Glenn Powell]

No real big difference between belted and non, if its for hunting bump shoulder .002+. Buy lots of powder, because that is one powder hungry round. RL22 is my go to for everything from 180 to 220.

 

[AR15DCM]

It will be for competition. I plan on using H1000 and 220gr SMK's.

 

[RandyD]

I reload the .300 Win. Mag. and I purchased a collet resizing die to size the case above the belt. Regular sizing dies do not resize this area of the cartridge. http://www.larrywillis.com/

 

[Bart B.]

When the .300 Winny was popular in long range prone matches, IMR4350 was "the" powder for best accuracy with Sierra HPMK 190's, 200's and 220's. While slower powders may well shoot these bullets out faster, they typically won't land as close together on paper at long range as with powders rated at about the same speed as IMR4350. I think slower powder's pressure curves are not as repeatable in shape and size. Vihtavuori also has powders in that range; one of them may work very well.

And the collet die from www.larrywillis.com is a must. After using a Redding or RCBS full length busing die (bushing diameter 2/1000ths smaller than loaded round neck diameter) to size most of the body back to near new dimensions and set the fired case shoulder back a couple thousandths, the collet die sizes the body all the way to the belt getting rid of that ridge in front of the belt that hurts accuracy. Decades ago, folks tried standard full length dies without expander balls alone but got better accuracy with new cases. Nobody consistantly did well with any neck only sizing process for belted cases.

Even today, one can get excellent accuracy with new belted cases; just seat the bullet out far enough to set back a few thousandths when chambered.