.308W reloads in AR10

I just load for accuracy and don’t really care about pushing for max velocity. I load a 155gr BTHP over H335. I can’t remember the exact charge weight right now, but I believe it’s at least 1.5-2gr below max. If I do my part, I get 1/2” groups at 100 with this load.

Ray P said:

When loading .308W for use in my AR-10, should I be keeping loads in the Service Rifle zone, or are hunting loads acceptable? I've just loaded mixed year Lake City brass with CCI LRPs, Hornady 150 gr BT-FMJs, in 0.2 grain increments to the powder range in the Hornady manual (max = 44.9 gr) for that bullet.

Yet Hodgdon, Nosler and Lyman all have Varget loads for 150 gr jacketed bullets up into the 46.5C and 47.0C level (2900 fps vs 2700 for the Hornady load).

Should I be reserving the higher pressure and velocity loads for my bolt action?

Lyman, but no other source, mentions that I should keep loads 1 to 2 grains lower than max if using mil spec brass. And I did see at the 44.9 gr load, the case looks to be full to just under the neck. This might be a compressed load if the bullet is seated to the cannelure.

Click to expand...

If you want to have rounds that feed and extract you are better off using "service rifle" loads.

Firstly, does what does more mean? What do you really get with the extra velocity, besides, extra velocity? Everything you read in print pushes increases in velocity, but they don't show any differences in wound channels. The comparisons are always in kinetic energy, a bogus measurement of lethality in my opinion, and bullet drop at over the horizon distances. Distances which are unethical, unlikely to encounter in most of the US, and beyond the marksmanship capability of most of humanity. But lets say, out to 300 yards, the drop on a 2700 versus 2900 fps bullet is going to be within your hold, and at 2700 fps the bullet will expand predictably at that distance.

I don't have an AR10, I have Garands, M1a's, PTR 91, and FAL's. I did not use Varget powder, tested it once in a match M1a and came to the conclusion it was a bit slow for the gas system. It caused case separations. I am going to recommend the any of the 4895 powders. That is, IMR 4895, H4895 and AA2495. Accurate Arms told me they blended AA2495 to the IMR 4895 pressure curve, and I shot kegs of the stuff in competition, and it shot very well. The 7.62 cartridge was developed with IMR 4895 powder so, in my opinion, it is first choice for gas guns chambered in 308 Win. I also like IMR 3031 because it is now short cut, and a little faster than IMR 4895. I want a powder that has a quick pressure drop, which increases the chance the case is not stuck to the chamber on extraction.

Based on my testing of 150 Hornady FMJ's, I would start with 42.5 grs IMR/H/4895 and stop at 43.5 grains. Looking at my data, 41.0 grains IMR 3031 worked well. (my notes say "outstanding accuracy")

You can experiment with higher powder charges, eventually you will find the powder charge level where your rifle rips the rim off of cartridges, sticking cases which require a cleaning rod to remove, and you will experience strange bolt over rides and cartridge jams in the magazine. You want these to occur at the range, where you have access to all your tools. I always carried a leatherman when shooting AR15's because clearing some loading port jams was impossible without needle nosed pliers. I also carried a cleaning rod inside the tube of my spotting scope, and I was very popular with those who had jams on the firing line.

Personally, I would start with service rifle starting loads, and work your way up to find the accuracy you desire. As Slam mentions, absolute velocity is not always the best path, and I agree.

In the AR-10... in your instance with Varget and a 150grn bullet, I think you would be better served with a little faster powder like iMR4895, or my favorite, IMR3031. If I were to use a slower powder, like IMR4064 or Varget in an AR-10, I would make sure I have an adjustable gas block... to adjust for the slower powder and not overgas (or undergas) the bolt, and/or with heavier bullets. You didn't mention your barrel length or gas system length. I built a .308 AR for a friend of mine, he gave me a 16" barrel with a midlength gas system... it was seriously overgassed with M80 surplus (150grn) ammos... so gas system length can be a factor.

Like the AR-15, pushing max pressure in an AR-10 can be a fast path to breaking things... like lug bolts.

If you have an adjustable gas block you can adjust it to keep from ripping the rims off. But then you may have problems with other ammo. But if you get over pressure signs you need to back the load down.

An adjustable gas block helps to mitigate many issues. I have AR-10 308s that wear adjustable blocks. I can shoot anything I want, suppressed or unsuppressed, without damage once I get it tuned in.

Many more options now than before too so it should be easy to find something that fits your needs and budget.

Most of my loads didn’t come from a manual with a service rifle distinction. I was using either Hodgden online information or Lyman manual data. I have a target and hunting load that cycle fine, but I also have an adjustable gas block. I have a second target load that I think will require turning the gas block down a bit. It throws brass to the 2 to 3 o’clock position. The others are about 4 o’clock. It’s worth noting the problem load is with a different powder than the other 2.

It depends on your rifle. Back when my AR10 didn't have an adjustable gas block I stayed in service rifle data, because once I got a little above it I started shredding brass. I have a 4.8 oz buffer and an adjustable gas block now, and can push it a lot more before brass starts getting beat up. As @Slamfire said, they do seem to run the best with powders in the 4895 burn speed range(mine seems to love AR Comp, 8208XBR, H4895), but I've run mine with powder as slow as N150 with good to great results since I put the adjustable gas block on it. My 150gr FMJ loads (42.5gr of AA2495 or IMR4895)are still "service rifle" loads, but I've been able to get a lot more out of some hunting loads I've been trying.

Ray P said:

Very good point. This one is an 18" (FN) barrel with rifle-length gas system.

Click to expand...

Velocity wise, you have really handicapped your self with an 18 inch barrel.


M1a, 22 inch Douglas barrel

150 gr Australian Ball MF83 headstamp
T = 78 °F 2-May-05

Ave Vel = 2806
Std Dev = 91
ES = 344
Low = 2612
High = 2956
Number rds = 10



PTR91 18" barrel
150 gr Australian Ball MF83 headstamp
30 April 2008 T = 75 °F

Ave Vel = 2599
Std Dev = 23
ES = 63
High = 2630
Low = 2567
N = 10



I experienced a loss of 200 fps going from a 22 inch barrel to an 18 inch barrel, and there is no way you can make that up by increasing pressures. It won't work well, I guarantee it.

I don't think you've necessarily handicapped yourself with that 18" barrel... it depends on the role it needs to fill. Yes, you are giving up absolute velocity, but if that isn't a specific goal, it doesn't matter.

I have a 16" barreled M1a (a Socom16.) It is a fantastic rifle... within it's limitations. I won't be lining up at Camp Perry with it, certainly, but for what I wanted it for... a high-powered carbine... it is excellent. Because of the shorter barrel, I trend to the faster powders... IMR3031, and particularly with lighter (110-150grn) bullets, although IMR4895 works well enough, too. Recently, I've decided to try 168grn bullets in the M1a, more of an experiment than anything, and I'll be starting with IMR4895 there.

I chose a 20” barrel. The only handicap I have is bad knees from carrying this thing.

Charlie98 said:

Recently, I've decided to try 168grn bullets in the M1a, more of an experiment than anything, and I'll be starting with IMR4895 there.

Click to expand...

Start with 40.5 grains IMR 4895 and end up at 41.5 grains with a 168. The classic load was 41.5 grains, but on a new, tight,match barrel, I would go 40.5 to 41.0 for 200 and 300 yards, shot plenty of cleans, function was perfect. At 600 yards, it more or less depended, but 41.5 grains was trouble free with a few rounds through the barrel, and accurate with a 168.

The 168 will tumble at 1000 yards, this is well known. The better bullet at 600 and 1000 was the 175 SMK.

I do recommend H4895 or AA2495, I ran my own tests with H4895 a M1a and could not tell a velocity difference over a chronograph.

I’ll probably try some H335 in mine but I just found some IMR 4064 so I’ll run through that first. I have some Amax 168 grain bullets I want to use with the IMR 4064. That powder has worked for 175 grain SMK & 180 grain SST bullets. I’d prefer to move to lighter bullets for H335.

I load a 155gr HPBT over H335 for mine. 20” heavy barrel, rifle length gas system, Superlative Arms adjustable gas block. 1/2 moa at 100 if I do my part.

This data is from a 18.5 inch barrel, 150 grain Hornady Interlock. 3031 is a winner in short barrel 308. This is in LC and FC brass. Not sure how it happened but the FC gave more compression than the LC. I think the FC was SB sized. Work up carefully. This is not max but it’s close. It shot right at an inch and it was temp sensitive. In the peak of summer this load left a slight ejector mark but held its accuracy.

Ray P said:

When loading .308W for use in my AR-10, should I be keeping loads in the Service Rifle zone, or are hunting loads acceptable? I've just loaded mixed year Lake City brass with CCI LRPs, Hornady 150 gr BT-FMJs, in 0.2 grain increments to the powder range in the Hornady manual (max = 44.9 gr) for that bullet.

Yet Hodgdon, Nosler and Lyman all have Varget loads for 150 gr jacketed bullets up into the 46.5C and 47.0C level (2900 fps vs 2700 for the Hornady load).

Should I be reserving the higher pressure and velocity loads for my bolt action?

Lyman, but no other source, mentions that I should keep loads 1 to 2 grains lower than max if using mil spec brass. And I did see at the 44.9 gr load, the case looks to be full to just under the neck. This might be a compressed load if the bullet is seated to the cannelure.

Click to expand...

Service rifle data is for rifles that might have physical limitations on what you can run due to some mechanical portion of the rifle cant handle the added pressure. There are no limitations like this on an AR10.
As others have pointed out here, if you have an adjustable gas block properly adjusted, you can do whatever you want, is long as you dont see pressure signs elsewhere.
I only use LC brass in my AR10, and while most places say cut back about 2gr from max load, Ive actually found that 1gr is more truthful, but you need to watch for pressure signs as your rifle isnt the same as mine. I use CCI200s, Varget, CFE 223, 8208 XBR, and probably a few others for powder.
However, while I have pushed the envelope pretty hard, my standard M80 ball cloner (150 FMJ) load only hits 2800fps. Its cheap, accurate, and easy to load. I run 168s for general plinking ammo are a bit hot, but Im shooting them at 500-700 yards on a consistent basis. My hunting loads with 175s are pushing hard and I have no concerns.

Ray P said:

I was surprised the Hornady manual didn't have an IMR 3031 load for their 150 gr FMJ-BT.

Click to expand...

bluejay75 said:

3031 is a winner in short barrel 308.

Click to expand...

It's generally considered too fast for rifle-length barrels and match-type loads, IMR4895 is considered the entry-level powder for even 150's in hunting loads. LIke BlueJay, I have found IMR3031 to be excellent in my short-barreled M1a, better even than IMR4895. I don't think IMR3031 is a good match for 168 or heavier bullets, however, but I'm sure there are exceptions to that, somewhere. It is likely you would see velocity benefits with a slower powder, like IMR4895, in a rifle barrel vs IMR3031.

DMW1116 said:

I’ll probably try some H335 in mine but I just found some IMR 4064 so I’ll run through that first. I have some Amax 168 grain bullets I want to use with the IMR 4064. That powder has worked for 175 grain SMK & 180 grain SST bullets. I’d prefer to move to lighter bullets for H335.

Click to expand...

I did a quick workup with H335 and the 150's as an alternate to IMR3031 or IMR4895 in my M1a (and in the .30-06 Garand...) it worked well enough, but showed pressure signs quickly (mashed primers,) and had a pretty good blast and fireball, at least compared to the IMR flavors. If you have a bunch with no other use for it, it's not terrible, but it's not my favorite, either. I think I settled on 41.5grn H335, #34 primer, in LC brass, under a 150grn Hornady FMJ for the .308. I consider that a near max load in my M1a. It gave me 2530fps, which is right around what my equivalent loads with IMR's 3031 or 4895 give me. I don't notice a difference under 300yds... but beyond that, the lower velocity of both the load and the short barrel start to take their toll.

Kaldor said:

However, while I have pushed the envelope pretty hard, my standard M80 ball cloner (150 FMJ) load only hits 2800fps. Its cheap, accurate, and easy to load.

Click to expand...

I quit trying to match factory velocity with my M80 duplicate load... it put me too close to the edge. I'm at about 95% of factory and everything is peachy.

H335 has proven blasty and prone to fireballs in my 30-30 too. I have a fair supply but the main thing I use it for is FMJ 223 rounds. It works well for that in both my 1/7 twist barrels. If it makes as burly a fireball in 308 as it does in 30-30 I’ll probably leave it to the 223.

Slamfire said:

The 7.62 cartridge was developed with IMR 4895 powder so, in my opinion, it is first choice for gas guns chambered in 308 Win. I also like IMR 3031 because it is now short cut, and a little faster than IMR 4895. I want a powder that has a quick pressure drop, which increases the chance the case is not stuck to the chamber on extraction.

Click to expand...

Along those lines - I had wondered whether too much unburnt IMR 4064 was making its way into my rifles' pistons (context: FGMM 168 and 175 clone loads).

The heads would have much more carbon than I'd anticipate, relative to Lake City "surplus."

I can't add much mostly because so much good advice has already been shared. I use IMR4895 with 168 SMK's. For the 150's I found a good surplus powder that works great. Found that for my 308 rifle it likes them right below 2600 velocity wise. That is with 168's or Hornady 150 FMJs. This includes my Milspec, GSR and AR10 (pre-safe act). I don't mix my LC and non LC Brass. In fact I got rid of all non Lake City. It shoots well enough for my skill set and use. I tried IMR4064, Varget, AA2520, and RL15. AA2520 actually worked best but sourcing it sometimes proved problematic. So I switched to Surplus 846 powder and IMR4895 which I could get in sufficient quantity. Sometimes you have to go with what ya got.