I've noticed that if one headstamp matches up 7.62x39 brass, the accuracy performance is actually quite good. Indeed, my best groups I've getting in Grendel so far, have been in FireForming PMC 7.62 cases using 90 TNT's. The rounds didn't even fill the chamber, since they were still 7.62 non-fireformed casings, yet I shot nearly half MOA - better than any other load I've ever shot.
I'm curious why that might be, and have two theories - that I'm putting out there to be laughed at.
1) My 7.62x39 load is on the mild-side, due to the variable nature of that brass dimensions (i.e. vastly different case vavolume depending on who made the brass). And maybe my gun and this round likes it more mild.
2) The recent look I've had into the SAAMI chambering of Grendel, where the neck is purposly cut bigger than it really needs to be. 7.62x39 brass is going to have a thicker neck, and fill up that space more fully, than original 6.5 Grendel brass. I'm wondering if that is a factor in the inherent accuracy improvement I'm seeing as well?
Obviously, the best way to ttest this, is to run my 7.62x39 spec Grendel load in true Grendel brass side-by-side, and see how they perform relative to each other. Which I think I may well do!
I'm curious why that might be, and have two theories - that I'm putting out there to be laughed at.
1) My 7.62x39 load is on the mild-side, due to the variable nature of that brass dimensions (i.e. vastly different case vavolume depending on who made the brass). And maybe my gun and this round likes it more mild.
2) The recent look I've had into the SAAMI chambering of Grendel, where the neck is purposly cut bigger than it really needs to be. 7.62x39 brass is going to have a thicker neck, and fill up that space more fully, than original 6.5 Grendel brass. I'm wondering if that is a factor in the inherent accuracy improvement I'm seeing as well?
Obviously, the best way to ttest this, is to run my 7.62x39 spec Grendel load in true Grendel brass side-by-side, and see how they perform relative to each other. Which I think I may well do!
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