This is a long post so sorry.........I've researched this many times via google results from other forums and I know it is an ancient question but I figured I'd get some fresh answers.
I know the whole history of the twists and bullet length and the consensus on what range of lengths/weights are best suited for a given twist, but here goes....
1) I have federal 55g ammo for my 16" M4. I've read that of course a 1:7 can handle that fine, but it will half the life of the barrel; copper foul it like crazy; is not too accurate due to over stabilization; can spin the jacket off; and blah blah blah.
Others say much of that is BS. jackets can only come apart with weights in the 40s. Also, over stabilization only makes a bullets trajectory drop sooner and more sharply, but it does so consistently, so an over stabilized bullet will be accurate, but it'll just shoot very low depending on the target distance. What say here?
Others say the commercial heavier ammo CAN be more accurate, but not the military M855 (is that right) since the placement of the steel core in the lead is not consistent and so can cause random accuracy issues.
2) does anyone know of manufacturers or reloaders who alter the velocity of a bullet to make it compatible with a barrel length and twist it normally may not be compatible with? I'm not sure if I'm correct on this but my thinking is that an 80g bullet length would not be expected to stabilize in a 16" 1:9 barrel, but in theory if you had maybe a longer 20" or so barrel that added an extra 800-100fps, the round would stabilize nicely in the barrel with the same twist. Or if you kept the same 16" 1:9 but reloaded to increase the velocity enough, the 80g should stabilize nicely. Just curious.
And the other way around, is there any ammo out there like 40-55g that is intentionally loaded not do hot to drop velocity enough that the copper doesn't come apart, but there's enough energy to cycle the action properly?
I was hoping I could learn from a discussion that this topic will hopefully provoke, since it seems to be contentious amongst military and non military guys.
Thanks in advance!