05-17-2011, 06:24 PM
1. Agree that the main challenge with 6.5 is MV.
2. Thinking about Liberty Ammunitions T3 copper body/steel tip bullets. They claim a .3 BC for a 62gr @ 3000 fps from a 20" bbl. Sectional density for a 5.56mm 62gr is around .178. SD for a 6.5mm 100 is .205 and a 107 is .219 (same as a 5.56 77gr). I'd like to explore the concept of a 6.5mm T3 with a lighter bullet for ARs and a heavier bullet for LMGs. This reflects that I'm not quite ready to give up on a unified infantry cartridge and that a lighter 6.5 bullet for ARs would help minimize the weight difference between 5.56 NATO and 6.5G, since most of the weight difference between the cartridges resides in the bullet.
3. Thoughts on the Knight's Armament Stoner LMG? It has constant recoil. Convert to 65G as a proof of concept?
4. Still think 6mm is too similar to 5.56 to change. Why not simply up 5.56 to a 90-grain projectile in a new case? Great BC and SD. Thus, I maintain that 6.5 very nicely splits the difference between 5.56 and 7.62 and that the extra bullet mass counts for . . . something!
(Seriously, I'm thinking construction material barrier penetration.)
John
2. Thinking about Liberty Ammunitions T3 copper body/steel tip bullets. They claim a .3 BC for a 62gr @ 3000 fps from a 20" bbl. Sectional density for a 5.56mm 62gr is around .178. SD for a 6.5mm 100 is .205 and a 107 is .219 (same as a 5.56 77gr). I'd like to explore the concept of a 6.5mm T3 with a lighter bullet for ARs and a heavier bullet for LMGs. This reflects that I'm not quite ready to give up on a unified infantry cartridge and that a lighter 6.5 bullet for ARs would help minimize the weight difference between 5.56 NATO and 6.5G, since most of the weight difference between the cartridges resides in the bullet.
3. Thoughts on the Knight's Armament Stoner LMG? It has constant recoil. Convert to 65G as a proof of concept?
4. Still think 6mm is too similar to 5.56 to change. Why not simply up 5.56 to a 90-grain projectile in a new case? Great BC and SD. Thus, I maintain that 6.5 very nicely splits the difference between 5.56 and 7.62 and that the extra bullet mass counts for . . . something!
(Seriously, I'm thinking construction material barrier penetration.)John