I noticed the AR10 has a twist rate of 1:11.25". Their website claims 1.5 to 2.0 MOA, not anything to write home about but decent for a NATO chambered rifle in my opinion. What's the heaviest bullet that can be used and still achieve the advertised accuracy?

I noticed the DPMS and RRA .308 rifles have a 1:10" twist rate like my Savage .308 bolt gun. I get great results out of the Savage with 168 gr SMK bullets. Thanks in advance for any and all help or advice.

Shabo

Ooops I thought I was in the AR10 forum. Mods please move this if necessary. Sorry.

its actually more about length than about weight-- but longer bullets tend to be heavier.  You should be fine up to 175.  Every barrel has a preference, and its not always what its supposed to be.  Like 1:10 is supposed to like 175 more than 168, and 1:11 should like 168 more than 175.  The only way to know is to try it.

For example the Berger 210gr VLD has a commended twist of 1:11, and that is a LONG bullet.  

One of the twist calculator I saw says the max bullet lenght for twists:

twist     max bullet length
1:11      1.29"
1:10      1.42"

Twist rate/ Greenhill Formula

The thing is that this is all theoretical, and most agree Greenhill is a little conservative.

Heavy bullets are long. To get a long bullet to fit into the magazine you have to seat it deep into the case. By seating it deep, you lose powder volume within the case and velocity suffers.

I know a few guys over at the Hide that ran the 190s with good results.I run 178 AMAXs threw mine and have excellent results and these bullets are quite a bit longer than the 175 SMK but my is a 1/10. I have a buddy that runs them threw a 1/11.25 with no problems either...

I would says 190s if you want to use the mag, you could get heavier but it would be a single shot.

175 SMK work just fine for me,

AR10's have 1in11.25" ? Has anyone check that out to make sure because anything not a whole number means they single cut the riflings. Its not a pulled button style and barrels like that shoot better that 1 moa on a bad day.