Originally Posted by perfectweapon
I was told if I wanted to fire a higher grain bullet like a 55grain 5.56
I needed to change the barrel from 1.9 twist to a 1.7 twist is that right and what else would I need to change. Thanks.
Yes, probably spoken by one of the fanboys for the 5 flavor-of-the-day manufacturers who only make 1:7 twist barrels on their AR-15's. The truth is 1:9 will work perfectly for up to 69-70 grain .223/5.56 bullets that most people will use and will be as accurate as you could want. Some folks have reported using even heavier grained bullts in their 1:9 twist AR's with great success, but it's a crap-shoot as to whether your own rifle will do so. As was stated above, the fast twist barrels were developed for the military to stabilize tracer bullets in short barreled, full auto. M16's & M4's. Somehow from that, many civilian semi-auto. AR owners jumped on the bandwagon and asserted that every AR needed to be 1:7 twist barrel or it was junk. Nothing could be farther from the truth.