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Optimum barrel length for 6.5 Swede
v35
Member Posts: 12,710 ✭✭✭
I'm thinking of chopping up a Swede, setting back the barrel to rethroat for a 139 grain bullet and restock with a full length Mannlicher.
What barrel length is optimum for the 6.5 Swede ?
What barrel length is optimum for the 6.5 Swede ?
Comments
IMO, 28". I say that because the CG-63 I had, had a 28" barrel and it shot 'par excellence'. I always got better velocities out of it than I do my current CZ 550 in 6.5x55.
Is the AI designation applicable to any standard cartridge that has the shoulder blown out in the Ackley manner?
My take on that is only those cartridges with shoulder blown out to 40 deg. and the diameter blown out to .459. Otherwise it's an 'improved' case with no AI for 'Ackley Improved'. Or often-times, such as the 6mmXC and 6mm Creedmoor, improved cases start out proprietary.
Real Mannlicher Schoenauers run from 17.7 - 20 inch barrels in full stocks. Most of the other brands in the style settled out at 20 inches. The CZ 550FS is cataloged at 20.6", which is strange, it doesn't come out even in metric. I vaguely recall seeing a full stock 22 inch that did not look out of proportion. There were some built longer in The Old Days, but they look a bit funny.
I don't know if you will be able to tell the difference in a barrel set back on a 139 gr bullet when it is bound up in a full stock.
By the way, Ackley himself said that "Improved" was a terrible word choice because it implies that such modified rounds are invariably "better" than the unchanged round - and they usually aren't.
Is the AI designation applicable to any standard cartridge that has the shoulder blown out in the Ackley manner?
no, most are just given the AI designation, since Parker was the one who brought these changed cases into the public eye, more or less. The correct designation would simply be "improved" or some other name.
I prefer them (have a 6.5-06imp, 6.5x55imp, and 280AI) because they almost completely stop case stretch and headspace very positively off that shoulder. They don't get a huge amount of internal capacity increase or the mystical velocity increase claimed by some. the reason some folks get much improved velocities is because they have run the improved case so far up the pressure curve in their loading, due to the fact that improved cases don't show pressure signs anywhere near as readily as tapered cases with slow shoulder angles.
I discovered this by runnning a 6.5-06imp to 3208fps with a 140gr a-max out of a 26" barrel[:0] needless to say, even though there was no indication on high pressures on any of the cases, nor sticky bolt lift,....the primer pockets were pretty much wasted after that firing. Chronos are IMHO a must when working with improved cases.