The Firing Line Forums - View Single Post - Heaviest bullet for ar15 in 5.56 (single feed)?

lordmorgul · January 10, 2019, 06:42 PM

Chambering by single feed is not the main issue but stability when fired, and good engagement in case mouth (cylindrical area of the bullet). Start with stability, bullet length, barrel twist, and then load longest bullet your specific barrel can handle stabilizing because why bother launching it otherwise.

I have 1:8 twist 75gr Hornady ELD bullets working in 20” barrel. It’s listed as not stable in 1:8 by Hornady but I think it is just marginal and seems ok in my shooting environment and barrel. They make up to 90 gr ELD with long ogives so it’s relatively easy to chamber a bullet without being lodged into the rifling lands but be something too long to stabilize.

I’ve measured these bullet lengths, it is not super easy to find them for all bullets.

Hornady 75 gr ELD-M 1.116”, G1 .43, G7 .220
Hornady 70 gr GMX 1.047”, G1 .350
Hornady 73 gr ELD-M 1.056”, G1 .398, G7 .200
Hornady 75 gr BTHP OTM 0.988” G1 .395

Andrew - Lancaster, CA
NRA Life Member, Calguns.net contributor, CGF / SAF / CRPA / FPC / NAGR / NRA-ILA contributor, USCCA member

January 10, 2019, 06:42 PM	#4
lordmorgul Senior Member Join Date: August 18, 2016 Posts: 206	Heaviest bullet for ar15 in 5.56 (single feed)? Chambering by single feed is not the main issue but stability when fired, and good engagement in case mouth (cylindrical area of the bullet). Start with stability, bullet length, barrel twist, and then load longest bullet your specific barrel can handle stabilizing because why bother launching it otherwise. I have 1:8 twist 75gr Hornady ELD bullets working in 20” barrel. It’s listed as not stable in 1:8 by Hornady but I think it is just marginal and seems ok in my shooting environment and barrel. They make up to 90 gr ELD with long ogives so it’s relatively easy to chamber a bullet without being lodged into the rifling lands but be something too long to stabilize. I’ve measured these bullet lengths, it is not super easy to find them for all bullets. Hornady 75 gr ELD-M 1.116”, G1 .43, G7 .220 Hornady 70 gr GMX 1.047”, G1 .350 Hornady 73 gr ELD-M 1.056”, G1 .398, G7 .200 Hornady 75 gr BTHP OTM 0.988” G1 .395 Andrew - Lancaster, CA NRA Life Member, Calguns.net contributor, CGF / SAF / CRPA / FPC / NAGR / NRA-ILA contributor, USCCA member Last edited by lordmorgul; January 10, 2019 at 06:50 PM.