If you are comparing the performance of the 6.5CM to the .270 over normal hunting ranges , here are a few points to factor into your calculations:
1. Use a well-constructed hunting bullet that you can shoot through the shoulder of a deer without it blowing up before getting to the vitals, perhaps compare the 140 grain Accubond or TGK in .270 to a similar CM bullet
2. Use a muzzle velocity that a temperature stable powder gives you such as H4350 or H4831sc that will work well at -4 degrees to 100 degrees without significantly affecting your velocity , pressure and point of impact
3. Use the same length barrel 22" to 24"
4. Do not use a 200 yd zero. Sight your .270 in for 3" high at 100 yds and the CM for the same.
5. Use your accurate load of temperature stable powder which gives a moderate pressure, not the exaggerated published loads of factory loaded ammunition, nor maximum load
6. factor in that the .270 has 10 % more cross-sectional area than the 6.5 for a bigger wound channel
7. Give drop figures at 100 (+3"), 200, 300 , 350 yds
8. State what loads, projectile, barrel length you are using
.277 vs .264 is only about 5% larger unexpanded, same if you use 1.5x for expanded differences.
