Originally Posted By: venaticOriginally Posted By: nastynatesfishMy 22/6mm was reaching just over 4200fps with a 75gr amax and 53.5gr retumbo. I think a 22/6mm AI would fill your speed need just fine and still get 1000 rounds or so out of it
4200fps with the 75gr????? I have friends who have moved on to other cartridges away from 22/6mm because they could never get much over 3500-3600 with the 75-80gr bullets from 26-29 inch barrels so you must have knew something they didn't.
I suppose stranger things have happened but this almost sounds a little Unicorn-esque.
I have a standard, not Ack Imp, 22-6mm with a 1-9tw, which is a little slower than most as many are faster twists, and with a 75gr Berger VLD, even before I had the barrel shortened from 28 down to 26, 3600 was about it. Tried a variety of powders and I could squeeze a little more out of it but I could also push new primers in with my tongue on the next loading, and in all honesty, mine shoots much better at 3450-3500 than it does at 3600. I've run it across an Oehler 35P and two different Magnetospeed Chrono's with all three being withing 20 fps or less
That 3600, give or take, with 75-80gr. bullets seems to be where everyone is at and I hear the occasional 3800-ish every so often and I'd bet most of those are running at redline, but we're talking 4100-4200 and that's a HUGE jump above the norm and for me, just a little to big of a stretch to be believable with a 75 grain bullet.
We had a guy that used to praise the velocity of his 338-378 Wby Mag with 300gr SMK's like it was the second coming of Christ. With its 26in barrel he could get 3200 fps with 300's and his loads weren't hot, the bullets weren't seated wayyyyy out, in fact the OAL of his ammo would feed through the magazine. Everyone was amazed and it seemed as though there was just something "special" about that gun. But something just didn't seem quite right and remember I said the OAL of his ammo wasn't real long, well someone got the bright idea to bring a scale to the range and asked to see one of his reloads and weighed it. Hmmm, are these loaded with 250 SMK's or 300 SMK's because mine weigh almost exactly 50 grains more than yours, the question was asked. The response "well I thought they were 300's" lol mystery solved.