grayfox Wrote:While Hodgdon doesn't say by how much the powder is compressed (only using a "C" for compressed load), Klem is there some indication you know of, how much that load might be compressed. I'm thinking that maybe 100.5%, vs. say 104%, the burn characteristics might not change much for the first, but a lot for the second...
Gray,
I don't have a fundamental issue with compressed loads, it's just that you need to be careful. For years I used a drop tube, trying to cram as much 2208 (Varget) into a 223 case as possible. This, so that a heavy match bullet could reach 1,000yds with as much velocity as possible. Finish it off by tapping or holding against a tumbler, but you could still feel the crunch as the bullet went in. After 103% compressed you have to accept you are changing the fill/pressure relationship.
Look, I don't think the load being hot, let alone compressed is the main issue here. I'm just saying you cannot discount that it may have contributed to the case rupture, in a way a lighter load might not have. The OP had other tell-tale issues of failure-to-fire and stuck cases.
The OP reports a range of base-to-datum sized measurements: from 1.22 to 1.2301 (.01" range). This should not be an issue as long as that range is within the SAAMI range of max chamber 1.2301", and SAAMI's min ammunition spec 1.213" (so a .017" range). This assumes Odin has machined the chamber to SAAMI, and the bolt combines with the chamber to comply.
(Stone, I'd be careful comparing your Hornady headspace gauge readings to SAAMI's blueprint specs because unless your B350 insert is EXACTLY .350" ID then you are comparing apples with oranges).
My range of base-to-datum sized cases in this calibre is about 0.004" so the OP's 0.01" is a bit more generous but still potentially fine. Whether some of the cases are borderline too much headspace, made more possible by the chamber/bolt combination failing the NOGO (before firing), plus Odin's overly generous chamber mouth reaming not supporting the case enough, and maybe even a warm load supplying the pressure, is certainly possible.