I have a question that has puzzled me for some time and am not certain that there is a definitive answer. Assume I have a 7mm Rem Mag with 160 grain Accubond ahead of 68 grains of RL 25 with a COL of 3.280 and I get a velocity of 3000. Assume that my magazine will take a bullet of 3.300 and I am still about 20 thousandths of the lands. If I extend the OAL to the 3.300 should I expect a reduction in the velocity and can I safetly add more powder, starting in maybe half grain increments and finally should I expect to achieve greater velocities with extending the bullet out to 3.300 as opposed to 3.280, assuming that I add more powder? Thank you for any assitance that you may provide.

Actually, pressure/vel. should increase as you get closer to tha lands (freebore). Try moving the bullet in 0.010 then out the same & record your vel. before you think about adding powder.

I don't think that increasing your COL by .020 would result in a measurable increase in case capacity or pressure unless it accomplishes a hard jam into the lands. IMHO Jim

.02 would give you a very maginal increase in capacity assuming you don't get into the lands. Loadtech says your load could increase .4grs and gain you 5fps. If you could increase to 3.5 and adjust your throat then your load could increase 3-4 grs and gain 60-70FPS. You would still have around .28" of bullet in the case. When I build a normal magnum in a M70 I take the spacer out of the back and set it up to have the bullet seated to the bottom of the neck to maximize my net capacity. I wouldn't fool with .02"