I've been splitting necks on about 2-5% of my Lapua 6.5 Grendel brass. I did some measurements to try and figure out what was going on.
Average fired neck diameter = .2950"
Average sized neck diameter = .2872"
Average loaded neck diameter = .2884"
Average neck tension = .0012"
Bullets used were Sierra 107gr Matchkings. Rounds were fired in a 16" Alexander Arms tactical Grendel upper. Dies are Forster Ultra dies.
If I interpret these numbers right, the most amount of brass movement occurs when the round is fired (.0076" assuming .001" springback). This would indicate that the 6.5 Grendel chamber throat diameter is about .2960".
Interestingly, the .264LBC reamer dimensions indicate a tighter .2948" throat.
So, my questions are: Do any other Grendel shooters have similar issues? Is a neck clearance of .0066"-.0076" excessive? Is the answer "this is normal, just get over it"?
--Rootshot
Average fired neck diameter = .2950"
Average sized neck diameter = .2872"
Average loaded neck diameter = .2884"
Average neck tension = .0012"
Bullets used were Sierra 107gr Matchkings. Rounds were fired in a 16" Alexander Arms tactical Grendel upper. Dies are Forster Ultra dies.
If I interpret these numbers right, the most amount of brass movement occurs when the round is fired (.0076" assuming .001" springback). This would indicate that the 6.5 Grendel chamber throat diameter is about .2960".
Interestingly, the .264LBC reamer dimensions indicate a tighter .2948" throat.
So, my questions are: Do any other Grendel shooters have similar issues? Is a neck clearance of .0066"-.0076" excessive? Is the answer "this is normal, just get over it"?
--Rootshot