.257AI will group better than the .257 mag or the 25-06 due to a better case design alone. But more importantly is that it works just fine with a 24" or a 26" barrel. Cases are 57mm in length, and fit the magazine well much better when using the long VLD bullets so popular on this board. P.O. Ackley says many times over that an improved 57mm case will shoot just as fast a the 30-06 case length. A 25-06AI will go no faster than 3350 fps with a jet pack attached. A .257 mag will go about 3550 fps with a lot more powder. A .257AI will do about 3300 fps as well. Now I too familure with the .257's and the 25-06 and .257 mags, and have chronographed a lot of rounds thru these barrels. Have shot them thru everything from 28" barrels down to 22" barrels. With the exception of the Weatherby and some super slow powders there's just not much speed in there to be gained. Whatkind of chamber pressures are you talking? Bob Hutton claimed to have got 3800 fps with the 100 grain bullet in the 25-06AI, but no one has ever came close to duplicating these speeds. Ackley upfront says 3400fps maybe, but probably 3300 is more realistic.
gary
I also hear that a 308 will group better than a 300WM, I shoot both & I am not too sure the 300WM does so bad compared to a 308, esp. after 800 yds. After Kirby worked over my Sendero
25-06AI, .25-.40 MOA groups were common with the 125 Wildcat, 100 & 115BT. Would the Bob give me .15-.30 MOA instead, who knows, but I have seen that a broad range of rounds will produce very small groups with a good barrel, good loads & a good shooter, so much so that it gets hard to tell which cartridge groups better. I am merely guessing, but if Buffalobob took
an Antelope at a 1000yds with his 257 Wea, it likely groups OK. So, it might be inherently accurate.
I don't know where a guy named Bob Hutton comes into this, but I saw where backwoods83 stated he got 3800 with the 100 in a 257 Wea.
, that seems a little fast, but I don't know the particulars of his rifle.
"Ackley upfront says 3400 maybe, but 3300 is more realistic." Did Mr. Ackley have access to RL 22, 25, Retumbo, Magnum powder, etc. ? Again, it seems strange to talk about what Ackley could get out of a given round before these slower propellants were invented. I do know that tons of 257 wea. rifles with 26" tubes get 3600 & change with a 100 gr. easily, some will beat that a little. I load for two 26" std. 25-06's & 3350-3400 is no trick with RL25 & one likes the 115BT at 3200. With the 25-06AI I can get 3475-3500 with the 100, 3300 with 115 & 3200 with 125 Wildcat. But then again, my powders & primers are not Woodstock era either.