Okay, so this thread isn’t about a gun in my safe, but it’s a question that I’ve never found an answer to, so I thought I’d pose it to CB…
For all those “gain twist” Carcanos out there that got Bubba’d and their barrels cut down, thus eliminating the faster twist in the gain twist, what can be done to shoot them? Is it an annoyingly light boolit? An annoyingly heavy boolit? Keep the velocity down?
Add to all this the seemingly wide range of twist rates we encounter - a 45 ACP at 1:16 shooting the projectile equivalent of a baseball or a 444 Marlin and it’s old 1:20 or 1:38 twist shooting a slightly elongated baseball, but then we’ve got a AR zipping out a pill at 1:7 and a 22/250 shooting the same pill - a bit faster - at 1:12.
I fundamentally understand rifling and twist rates, but my little brain struggles mightily when we start to talk about how this speed of twist will stabilize this bullet/boolit and this one won’t, or this caliber and this twist will stabilize the bullet/boolit and this caliber, the same twist is a recipe for disaster. And then there’s the overall weight and length of the projectile, which REALLY makes my head hurt. I’ve seen there are several formulas to calculate this stuff, too, both in terms of the size/weight of the projectile in order to stabilize it (the lowest RPM needed to get it to fly right) and the highest velocity (and thus RPM) it can structurally withstand.
Ultimately, the “Carcano” example is merely a common one we might have run into in the military guns, but I think it’s a good illustration of what I’m trying to ask. An equally useful one in the modern era is the fascination with the heavy-for-caliber (and thus “longer”) subsonic. boolits, which are fun to shoot, but again, the twist rate seemingly dictates what can and cannot be done in respect to boolit weight, yet the VLD series of target bullets (Berger, for example) run long bullets and conventional weights (up to a point) and performance is - seemingly - sublime.
Is there an easy way to think of all this - and actually remember it?
I need to go lay down now…
Cree