1/8 works, even with the long heavies. 1/7 may be more optimal for some.
Remember that depending on the maker, your barrel may be 1/8, +/-. Sometimes by a fair stretch.
1/8 works, even with the long heavies. 1/7 may be more optimal for some.
Remember that depending on the maker, your barrel may be 1/8, +/-. Sometimes by a fair stretch.
2012 National Zumba Endurance Champion
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Not the response you quoted, but I do the 75gr ELD in 1:8 barrel AR15 at 2.344 to 2.349 OAL single loaded.
Ballistic AE app calculates Miller Stability of 75 gr ELD as marginal at 1.33 in 1:8 with a 1.116 projectile length (my measured average value). For ref a 1:7 twist brings that to 1.74 stability which is well stabilized.
Andrew - Lancaster, CA
NRA Life Member, CRPA member, Calguns.net contributor, CGF / SAF / FPC / CCRKBA / GOA / NAGR / NRA-ILA contributor, USCCA member - Support your defenders!
Last edited by lordmorgul; 06-30-20 at 22:58.
Havent measured the actual twist, that barrel is Green Mountain Rifle GM-M20 20 SPR fluted. The load is 75gr ELD, 21.6gr LT-32 OAL 2.344 Winchester standard primer, 2780fps in 20.
http://www.gmriflebarrel.com/gm-m20-...wylde-chamber/
The fact that my Mini14 Tactical with a 1:9 nominal twist shoots the 75gr OTM bullets (0.985) quite well and calculates as a failing stability tells me there is probably room here at high desert average temps and ~2700ft altitude.
Andrew - Lancaster, CA
NRA Life Member, CRPA member, Calguns.net contributor, CGF / SAF / FPC / CCRKBA / GOA / NAGR / NRA-ILA contributor, USCCA member - Support your defenders!
Last edited by lordmorgul; 06-30-20 at 23:03.
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