What has been said is all true. The M80 bullet when seated to the cannelure in a 30-06 will have a shorter OAL, than the M2 bullet. 1:12 is better for lighter bullets than 1:10 but within 200 yards it probably doesn't matter. Faster twists usually are more versatile. In the AR-15 the 1:7 will shoot anything pretty well but the 1:12 shoots the M193 more accurately than the M855. The 30-06 holds more powder and can use heavier bullets (M1 Garands need to watch this). My take on any pulled military bullet is the weight variation. The M80's can be +/- 4 grains (made to cycle and go bang) so if you take the time to weight sort them, they work better. Most of the bulk 150 grain commercial FMJBT are better than any batch of pulled M2 or M80 due to their tighter tolerances and less handling. Just my experience with all of the above.
Dave