12-06-2011, 08:17 PM
LRRPF52 Wrote:The 6.5 LMG concept doesn't depend on a particular projectile material.It certainly seemed like it does. All you've talked about is using 130-144gr lead-core FMJ bullets, and have refused to discuss using "green" projectiles.
I understand that you intend to load significantly longer than 5.56 mag length. That isn't the issue. My concern is that 130-140gr bullets with two-piece steel/copper (US/Europe), steel/steel (Scandinavia), or one-piece steel (Eastern Europe) cores will be too long in that weight range to be feasible, if only due to the stability factors.
As I noted in a previous post, the 128gr GSC is the heaviest solid spitzer boattail on the market, and it is 1.51" long, requiring rifling twists in the 6-7" range. That info indicates a 130-140gr "green" bullet or conventional steel-core projectile would be 1.6-1.8" long. That makes for an extremely long L/D ratio, unusual even for 6.5mm. I don't know what rifling twist would be necessary to stabilize such spears, but it looks like it'd be faster than 1:6.