311-115 Boolit limits

[338RemUltraMag]

I have this mold and just bought a 16" wilson combat 1-12 twist 7.62x40 barrel, the upper limit for 120 gr bullets are 2550 fps. Are those type of speeds out of the question for a lead boolit?

Most of my shooting has been done in the 2000 fps range, any luck going faster?

Josh

[runfiverun]

try for 2300 first using your normal loads.
then slowly push from there i'd bet you can get close to 2400.
the 16" barrel is going to limit your exact velocity so you'll have to take what it gives.
try to stay on the slower end of the powder spectrum but don't go too slow.

[Larry Gibson]

Concure with runfiverun; with the 12" twist barrel you should be able to push 2200 fps and very good accuracy with the short stubby cast bullet if cast of a relatively hard and malleable alloy. GC must be seated squarely and use as slow burning powder as possible that provides ignition and burn reliability. If you do everything right you might push to 2300+ fps with useable accuracy. "Best, very good or useable" accuracy is how you define it. You will probably find the "best" accuracy below 2200 fps.

Larry Gibson

[338RemUltraMag]

I ask only because I am not sure if a 311041 will feed reliably in an AR platform. If it will I will be pushing that one to 2000, but as they say there is only one way to find out.

Josh

[felix]

If the barrel is meant for the standard carbine AR, I hope you ordered the barrel complete with the variable gas port orifice he offers. Using that device will save untold number of frustration hours in powder selection for perfect action cycling including the last shot out of the magazine. ... felix

[338RemUltraMag]

Juat bought the barrel and dies for now, I will cal them up and see what they have to say, this is my first AR build so we shall see!

[runfiverun]

the 041 has a fairly long nose and might not work in your magazine.
if that's the case p.m. me and i'll cast up some rcbs 30-150's which are similar but have a shorter nose than the 041, and also a 165 I have which works very well in the 308's short neck.
I'll send some to ya to try.

[338RemUltraMag]

Thanks Lamar!

I made a dummy that was under the OAL but not by a lot. I went looking for the Lee 312-155-2R and had a stroke when I found em...

[Patricklaw]

Thanks Lamar!

I made a dummy that was under the OAL but not by a lot. I went looking for the Lee 312-155-2R and had a stroke when I found em...
That's the mold that I'm using in mine and it's working really well now that I set the boolit back a little beyond the crimp grove to account for the fact that the ogive engages the lands when the round is chambered.

On the other bullet that you mentioned, I tried some 30 carbine bullets and they hung up in the feed ramps. A friend said that if I adjusted the ends of the feed lips on the mags it would change the angle at which the cartridge engages the feed ramps and cure my problem. I never did try it as I bought the Lee mold for this gun and my x39's as well.

Also, this is the holy grail of information on your new cartridge. . . except for the cast boolit info:
http://www.ar15.com/forums/t_3_121/382761_7_62x40mm_Information_Thread.html