2 ms·

What do you think of the 6.8mm SPC, which at first glance looks like it'll be better at long range (splitting the difference between 6.5 and 7mm was a compromis

by hga 12y ago

What do you think of the 6.8mm SPC, which at first glance looks like it'll be better at long range (splitting the difference between 6.5 and 7mm was a compromise between range and damage)? From the Wikipedia article the "[300 AAC] purpose is to achieve ballistics similar to the 7.62×39mm Soviet cartridge in an AR-15 platform while using standard AR-15 magazines at their normal capacity." Surely we can do better than that, 7.62×39mm is not a terrifically great round either.

exabrial 12y ago
6.8mm SPC is an incredible cartridge. It's far superior to .300 AAC in range and terminal effects. It offers a wide variety of loads including an effective subsonic load. There are a few quibbles about efficiencies (powder and materials): The standard infantrymen doesn't really need long range cartridge. However, the big reason I wouldn't suggest 6.8mm as an upgrade to the 5.56mm is the upgrade path is more expensive. While the 6.8mm _can_ work with the standard buffer tube spring, it's best those get upgraded for accuracy and shooter comfort. The 6.8mm requires a new bolt and barrel in the upper receiver. The 6.8mm also requires new magazines (to be used at full capacity). The 6.8mm requires new brass and new loading dies, so your ammo production lines have to change significantly. Finally, the chamber pressure increase in the 6.8mm may introduce reliability issues in certain models of the AR15, especially in the gas impingement system. And personally, I the recoil from the 6.8mm kinda sucks. The .300 AAC requires _merely_ a barrel swap. Everything else in the upper is compatible. The brass from 5.56mm can be cut down to make .300 AAC brass (yay for recycling) and existing loading dies can be used to load .300 AAC. The existing magazines can be used at full capacity. While the 6.8mm may be a superior round, I think the .300 AAC wins in terms of practicality. Just my opinion :)

by hga 12y ago

exabrial 12y ago

6.8mm SPC is an incredible cartridge. It's far superior to .300 AAC in range and terminal effects. It offers a wide variety of loads including an effective subsonic load. There are a few quibbles about efficiencies (powder and materials): The standard infantrymen doesn't really need long range cartridge. However, the big reason I wouldn't suggest 6.8mm as an upgrade to the 5.56mm is the upgrade path is more expensive. While the 6.8mm _can_ work with the standard buffer tube spring, it's best those get upgraded for accuracy and shooter comfort. The 6.8mm requires a new bolt and barrel in the upper receiver. The 6.8mm also requires new magazines (to be used at full capacity). The 6.8mm requires new brass and new loading dies, so your ammo production lines have to change significantly. Finally, the chamber pressure increase in the 6.8mm may introduce reliability issues in certain models of the AR15, especially in the gas impingement system. And personally, I the recoil from the 6.8mm kinda sucks. The .300 AAC requires _merely_ a barrel swap. Everything else in the upper is compatible. The brass from 5.56mm can be cut down to make .300 AAC brass (yay for recycling) and existing loading dies can be used to load .300 AAC. The existing magazines can be used at full capacity. While the 6.8mm may be a superior round, I think the .300 AAC wins in terms of practicality. Just my opinion :)