TonyRumore wrote:I have never tested a 24" 450, but the very first prototype .458 SOCOM I built back in early 2001 had a 24" barrel on it and a rifle length gas system. I don't recall the exact gas port hole, but I do remember having trouble getting it to run without opening up the gas port pretty damn big. It was around .135", maybe .140".
Tony Rumore
Tromix
Without digging out the 20" Franklin upper with rifle length port and pulling the gas block, I seem to recall having to open it up to .120+ to get it to start cycling potent loads reliably. What I did not see, before stopping last summer, was the premise as I understood it, behind the "Corvette" project. Namely a velocity improvement from being able to use slower powders. I suspect, the missing component was not just having a rifle length gas system, but a longer barrel as well. At .120+, it was just beginning to cycle heavy loads reliably. I'm not done with that project, since I would like it to cycle all reasonable load ranges reliably. Something that the mid-length system in the Bartz does and if you dismiss the really heavy loads, the carbine length original design does also. When you think about it. When Bushmaster rolled the carbine length 450b out of R&D and into production, it was designed to reliably function using the only available 250 FTX factory loada, under any adverse weather condition, clean or dirty. It did that. They threw us a few bones in publishing some really anemic (lawyer approved) alternative loads after the fact, but for the most part, if you wanted to expand its mission in terms of loads, you were on your own or within the scope of test results generated within this user forum. All points considered, the carbine length system, coupled with a known good quantity in Lil Gun powder, is amazingly diverse. That having been said and I realize I'm ruminating too much on this, the mid-length system, seems to be the best of both worlds in terms of broadening the diversity of successful loads in all but the shorter barrel designs. That's my take on it, but I do not consider myself a authoritative source on the subject. Just a good observer.
Hoot