I am currently having a .308 built on an FN SPR action from CDNN using a Brux 10 twist finishing at 20 inches, CDI Mag system, and a McMillan A3 stock. I like the action, and it was surprisingly smooth from the get go. Interestingly enough, I've read of some people having primer cratering issues with these actions and I think my gunsmith might have found the culprit:
My gunsmith had this to say:
"Will cause primer cratering that will look like pressure signs. I can bush the hole to make it crisp as it should be. I would go ahead and go to a .062" diameter pin since we are bushing it(further eliminates cratering). I can turn your stock pin down to .062"
Here are the after pics:
He also found that firing pin protrusion was only about .040", should be .050-.060", and corrected that.
Just wanted to share the pics, as I thought they were really interesting.
Best,
Josh
My gunsmith had this to say:
"Will cause primer cratering that will look like pressure signs. I can bush the hole to make it crisp as it should be. I would go ahead and go to a .062" diameter pin since we are bushing it(further eliminates cratering). I can turn your stock pin down to .062"
Here are the after pics:
He also found that firing pin protrusion was only about .040", should be .050-.060", and corrected that.
Just wanted to share the pics, as I thought they were really interesting.
Best,
Josh