Varmint Hunter and Goodgrouper,
I have heard good reports with these bullets used at higher velocities. Personally I have yet to see an A-Max handle anything over 3250 fps and hold extreme accuracy out of a true 1-8" barrel.
THe only experience I have with the 1-8 twist barrels with the A-Max bullets is with my personal 6mm-284 which shots the 105 gr A-Max into 1/5 moa levels at 500 yards until velocity gets to almost exactly 3250 fps. From there groups grow to about 4" at 500 yards.
The Berger 105 gr VLD was very similiar except that it grouped well only until 3200 fps.
With these velocities I might as well been shooting a 243 AI out of my 30" Lilja.
I have also witnessed one of my custom rifles
chambered in 22-6mm AI do nearly the exact same thing with the 75 gr A-Max when velocities hit just under 3300 fps with this rifle.
THe 6.5mm was in a custom 6.5 STW with a 1-8 twist. It lost accuracy in teh 3200 fps range as well.
I am not saying that these bullets disintegrate in mid air, only that their accuracy dropped off greatly in these three different rifles using 1-8 twists.
In contrast, like I stated before, I also have a custom rifle
that a customer is shooting the 105 gr A-Max out of a 6mm-06 at just shy of 3600 fps with groups in the 3's but this is with a 1-9 barrel.
I measure all of my barrels for twist before I start machining them. One would be suprised how a 1-8 barrel often turn out to be a 1-8.5 or even 1-9. This is especially true with the button rifled barrels.
Not so much a problem with cut rifled but alot of buttoned barrels are not what they are supposed to be.
I prefer and highly recommend Lilja barrels and they too are buttoned rifled but I have yet to see one that was not marked true.
I am not disclaiming you and your results, just stating that I have not had good results with the A-Max in 1-8 barrels loaded above 3250 fps.
Under that they are some of the most accurate bullets comercially made and on game performance is better then any other commercial long range bullet.
In all these cases I list, the barrels were 3 groove Lilja barrels. What barrels are you guys using to get these velocities with good accuracy?
Maybe its a 3 groove problem more then a velocity problem...
Have a good evening!!