Grandson bought an old bubba No4 mkI a while back. His first rifle with his money, he's 13. He has really been fascinated by the rifle, seems to be dealing well with the recoil of HXP milsurp ammo. I'd like to duplicate the military load as well as we can...I have some Grafs/Hornady 174 gr .312 bullets, some new Hornady brass, every flavor of IMR powders and most primer brands. I understand it's a good idea to fireform the new brass with the rim held firmly against the bolt face, either with an o-ring or a secondary shoulder on the neck?
Any tips at all greatly appreciated.
Honestly, there is no need to use o rings or anything like that. I remember years ago, when Lee Enfield boards were still popular, you would read all sorts of "unusual" ideas to make the rifles shoot better or increase brass life. For example, people incorrectly blamed headspace for excessively stretched brass. That was rarely the case. Because the 303 headspaces off the rim, the rifle could be perfectly gauged, but have a long chamber and the brass would stretch. I agree with Cat. either 4895 is appropriate. I would shoot 2 grains less than book max at most.
It was easier and faster to fireform with less than maximum loads. Let the case stretch without the trauma.
Two or three grains less than max will move the case without stressing the brass as much. Once it is stretched a bit, you can adjust your FL die to barely move the shoulder and use a collet die for two or three reloads until it does not want to chamber again.
I don't know how old your grandson is, but the iron sights will work ok when firing cartridges up to about 100 fps less than the 2440 fps design max.
Prvi Partizan brass is a bit thicker than US made stuff. The Greek surplus is good as well, so I would reload that.
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