Gentlemen,

I have received the following request, and I have no experience with this rifle.

Anyone has any suggestions?



"I have a 308 AR rifle with a 20 inch. I would like to get about 2700 to 2900 fps out of the rifle. The bullet would be no bigger than 180 grains. I would like load data for bullets between 150 to 180 grains, and that includes match bullets too"

The AR platform does not have the options a bolt gun can provide to achieve velocity goals. The main reason for this is you cannot use "slow powders". You have to use medium burn rate powders to avoid high gas port pressure.

In a 20" barrel AR10, you can achieve 2700-2725 fps with a 150 grain bullet and not exceed rated pressures. Any larger bullet will reduce MV.

Both the 168 and 175 HPBT bullets shoot very well out of my 20", 10 twist AR. Velocity will be in the range of 2500-2650 FPS at rated pressures.

I have had great results with Alliant's ARCOMP powder(consistent 0.5 MOA), and RL15. Hodgdon VARGET is good but does not provide quite the velocity or accuracy. IMR 4064 performs about the same as VARGET.

In my rifles, the Nosler 168 custom competition bullet at 2635 fps MV is amazingly accurate. Indeed, it seems more accurate than the bullet it emulates, the 168 Sierra MK. For hunting, you can switch to a 165 Sierra HP Game King and use about the same charge weights developed for the 168 HPBT. That bullet is the "Hammer of Thor" for White Tail deer.

Always, always full length resize the brass. I do not bother with a crimp as most dies provide ample neck tension for the .308 bullet. Military weight brass lasts much longer in these rifles than commercial weight brass.

I cannot be specific about charge weights. The reason for this is most AR's seem to achieve their best accuracy near the maximum charge weight/pressure. Charge weight will vary some for each rifle and the component mix. I can say most of them will shoot federal match ammo loaded with a 168 Sierra MK well. In my experience, the velocity of this ammo is very close to what I mentioned above.

I have found that any load safe for a bolt action will work in my AR10 without any problems. It does not have a gas piston like the M1 or M14 and that is what they are trying to protect. However, you don't want to use slow powders anyway; at least none at the IMR4350 level and slower; the med burning powders will give you higher velocities anyway. Just look in your Hornady or any other loading manual and pick some loads that give you the velocities you want; they will all be med burning types.

Thanks guys. I remember reading a post some time ago about powders for the 742 Remington and couldn't remember if it was use slow powders or not to use slow powders. I have RL15, Varget, CFE and some IMR4064 on hand so I will start with those. I have seen ARCOMP powder at a local gun shop that I may try as well.

I have a LAR 8 RockRiver .308. Just recently started reloading for it. First batch was with Varget, could find only 1 lb, but then couldn't find anymore. Found some AR-Comp in 8 lb container and so far so good. It got a good review in "American Rifleman". It has cycled reliably, is a bit smaller dog turd than the Varget and meters OK. I've only shot over my chronograph and not tested for accuracy yet. I have an older, skinny shoulder and I can't shoot it much at a time before my shoulder starts acting up over my chronograph as I'm at an awkward angle. I'm up to 43.0 gr AR-Comp with a Hornady SPFB bullet (16" barrel) and getting 2,559 to 2,604 fps. Alliant recommends 44.5 gr with a Hornady GMX & 24 " barrel & 2,929 fps.

I'm definitely in the market for a lead sled or equivalent.

I use 46grs of varget behind a 168 amax in my dpms and it loves it.