Building a new Mtn rifle! whats your take

[addicted]

Most 300 RUM's have a 1 in 10 twist, 3960 turnes in 1100 yards

assuming the spin doesnt slow down in conjuncion with the speed ofthe bullet.

[Jamieb]

I have no way of testing this myself but I've read that the spinning is a constant that don't change. The bullet is going to spin 1 time in 10" , it takes less time to cover that 10" at the muzzle then 1100yards but as the bullet slows so does the rotation so it's still turning once in 10" until its slows enough to unstablize witch for most bullets is around the subsonic barrier.

[longrange7mm]

Right Jamieb   :tup  if your shooting at 3300 fps  It will change if you shoot a faster/slower bullet or different twist rate of course

3300fps x (12/10) x 60 = RPM                             2970 x (12/10) x 60                 3450 x (12/10) x 60             

3300 x 1.2 x 60 = 237600 RPM at the muzzle         2970x 1.2 x 60 = 213840           3450 x 1.2 x 60 = 248400

237600/60 = 3960 rps at the muzzle                    213840/60 = 3564 rps                   248400/60 = 4140 rps

your bullet will loose velocity much faster than spin rate but will decrease slightly down range

as for how to calculate how many revolutions the bullet will loose down range Im not sure how to figure that out I would love to know if anyone knows

[whacker1]

Thank you for the clarification - not sure why I didn't pick up on the turret.  Must not have been my day. 

[longrange7mm]

Plans changed  just sold my 338 RUM to an outfitter in AK. I guess I will have to start hittn Pawn shops and gun shows looking for another action so I can build a Lighter 7mm RUM. 

[snowranger]

How about 6.5-284    high BC and excellent energy down range.

[addicted]

338 federal.  lots of bullet choices.

[280ackley]

Go with the the .280 Ackley.