Need Accurate AR-10 Loads!!!!

[moonzapa]

I have a new AR-10 (7.62x51/.308) and am anxious to wring out accurate loads for it. (My goal is 1- MOA) Being a bolt action gunner for quite some time, I never had the problem of long throated barrels and short magazines.

Other than the Speer 125 TNT bullets, I am not aware of other bullets that will seat close to the barrel LANS and still fit in the magazine. I would like to shoot the Hornady 150/155/165/168 bullets and plan to use this rifle for home security, and hog hunting.

I appreciate the help!

Thanks!

 

[ArchAngelCD]

From everything I've read and seen at the range seating bullets close to the rifling in semi-auto rifles on the AR platform has little to no effect on accuracy. Your time will be better spent finding the bullet/powder combination your AR likes best. My favorite 308 powder is IMR4064 when loading for a bolt action rifle. I have not personally loaded 7.62X51 ammo for an AR-10 but reloaders I know like AA2520 for their semi-auto 7.62X51 ammo. They like both the 168gr Sierra Match and 168gr Hornady Match bullets but even more so they like the newer 155gr Sierra Palma Match bullets. BUT, I have no first hand knowledge of those loads in an AR platform.

 

[mljdeckard]

Have you tried something like Federal Gold Match to see how well they run bone stock?

 

[30Cal]

Most of the 155/168/175 bullets are pretty insensitive to jump. Doesn't matter all that much if you have to seat them deeper.


Factory bolt guns all run long in the throat BTW. Heck, ANY factory gun, bolt or semi-auto, is probably limited by the mag length. If you seat the 125TNT to the lands, you'll have virtually zero neck tension. 2.75" is as far as I dare to go with them in a gasgun.

 

[Reloadron]

Personally I am not that big on the AR10 rifles:



However, if on the off chance I wanted to work up a match grade load for such a rifle I would start with the basics. I saw mention of the Federal Match .308 which in my rifle delivers good results. Unfortunately my rifle and your rifle are not the same rifle.

My experience is as follows. No two bolt action or semi-automatic rifles of the same make and manufacture with the same barrels will deliver the same result on any given day with the same ammunition. Been there and tried that and it just does not work.

Your AR 10 is just that, it is your rifle.Much like you, it will have a personality and special uniqueness unto itself. Since you can't change the rifle that leaves the loads to achieve the ultimate in accuracy. The road is long and hard. The road can also be expensive.

You want those sub 1 MOA groups? I suggest you start with knowing the exact chamber headspace of your rifle which will be unique o your rifle. A Precision MIC in .308 from RCBS would be a good start. Before you worry about seating bullets and free bore you need to know what your chamber actually is.

Personally, I would begin with 150 and 168 grain bullets. Work up some loads and see how they do. Write everything down including range results! Different powders and different bullets is what it is all about. The combinations become damn near infinite.

Since my rifle is sitting here and your rifle is sitting there for me to say Load XX.X grains of IMR 4064 with a Sierra MK 168 grain HPBT would be stupid at best.

Working from loading manuals I suggest you just work up some loads and see how they perform.

Ron

 

[Trent]

+1 - if you don't keep ACCURATE records, you're wasting your time and components.

 

[badnova]

Ar 10

I started my LAR 8 on Federal Match and Black Hills Match 168gr. and worked from there.
Federal is pretty hard to beat in a gas gun

 

[mtrmn]

I found that 150 and 168 grain bullets work very well with 4895 and TAC in the 40 to 42 gr range.
This from a Bushmaster BAR10--the early version of the RRA LAR8. 1 IN 10 twist 20" bbl. Anything over 42 gr charge gives pressure signs, but 42 gr with 150's turns out good groups for me. I'm NO match shooter though.

 

[Jasper1573]

Somewhat depends on barrel length and twist rate as well. I have a friend with an AR-10...24 inch heavy barrel, 1:10 twist. His rifle shoots 175 grain matchkings at standard 2.800 COAL...sub-MOA well past 300 yards. Velocity is around 2600 fps.

You might work up a load to mimic this if your rifle is similar to his...if not, then maybe something else.

As stated above, whatever combinations you try, keep detailed records of components and accuracy results of different loads. Eventually one load will stand out as somewhat (or much) more accurate than all the others. If you are fortunate, you may even find two good loads that shoot equally as well as each other.

 

[GW Staar]

I have a new AR-10 (7.62x51/.308) and am anxious to wring out accurate loads for it. (My goal is 1- MOA) Being a bolt action gunner for quite some time, I never had the problem of long throated barrels and short magazines.

Thanks!

Well, its not that big of a problem....these guns are accurate without a bullet to the lands....in fact, its not a good idea at all loading an AR one cartridge at a time like you would a bench rest gun. Dangerous in fact. The Sierra article below explains why.
First of all: what is it chambered for, Nato or .308 commercial. That makes a bigger difference than you might think. You can load hotter in the 7.62X51 chamber than the .308.....I don't have the figures, but I'm betting one of our walking encyclopedias will fill you in.

Second: before you even think about reloading for it, read Reloading for Gas Guns from Sierra. That's one of the good chapters in Sierra's manual, you can read on the internet.

I have a Remington R25 (DPMS Ar10 clone) chambered in .308. I bought both RCBS's Precision Mic and Hornady's OAL tool with special case for it, because I wanted to make dang sure I sized correctly and seated correctly for the rifle, because I was aware of people destroying their rifles with their badly headspaced reloads.

Do note, that neither tool was designed semi-autos, but the RCBS tool is great for setting up your sizer to bump the shoulder back enough but not too much for proper headspacing.

It was not so good at checking & setting bullet seating length, So I bought the Hornady/Stoneypoint Chamber-all OAL Gauge, and special case that holds a "real" bullet of the type you want to reload, unlike the little plastic generic bullet shape on the RCBS tool.
Picture shows .223 tools, mine of course is .308.

What I determined after all that...was that the magazine limit on my Remington came long before the bullets reached the lands, so seating the bullet just off the lands wasn't possible. But as it turned out, it didn't matter. I just seated barely shorter than the magazine, and the gun shot a nickel-sized group with my first 5 shots. That first load was LC cases, IMR 4895, Nosler 168 grain Ballistic tips, and CCI primers.

 

[Trent]

The biggest difference on 308 vs. 7.62x51 is the rim thickness on the 7.62x51 is spec'd out slightly thicker by .01" to make the rim somewhat tougher for use in full auto weapons.

Also, you got the pressure backwards.

308 is rated for 62,000 PSI, 7.62x51 is rated at 60,200 PSI. The commercial 308 round is hotter than the military round.

Some of the confusion comes from "surplus" ammo - people assume it was made for machineguns and is hotter, as it causes the bolts in their pretty hunting rifles to stick when it's fired. This is mainly due to varying quality brass from foreign countries, not necessarily pressure. Softer (or less consistently formed) brass will expand and grab that chamber pretty dang hard, hard enough to get out the rubber mallet. Some other surplus ammo is so poorly constructed they won't chamber in a tight chambered bolt gun, but this is because modern bolt guns tend to have as little headspace as possible to preserve reloaded brass (one of my Krieger barrels is headspaced so brass doesn't grow, lengthwise, AT ALL), while machineguns tend to be considerably looser. They don't care about reloading spent shells from those; and as long as the cases aren't rupturing when they're fired, a belt gun will pass the "kicking tires" test.

Now, 5.56 vs. 223 is a whole different animal, 5.56 dimensions are diminutive by comparison and thicker brass walls DO make a difference when you load.

 

[popper]

168 Amax or Accurate 31-165B cast or hornady 150 SPP work for me with H4895, varget or AR comp. LFN works fine. Match ammo is for matches, not pigs. For your specified use, use the heaviest your 1:10 will take and use lowest load of powder that cycles properly. Make sure the primer is seated below flush and HS is correct. Use a case gauge with fired case to adjust die for correct HS. HD & pigs is the same, 100% reliability @ 50 yds, a load you can get repeatable 2-3 shots fast.

 

[AABEN]

I have a new AR-10 (7.62x51/.308) and am anxious to wring out accurate loads for it. (My goal is 1- MOA) Being a bolt action gunner for quite some time, I never had the problem of long throated barrels and short magazines.

Other than the Speer 125 TNT bullets, I am not aware of other bullets that will seat close to the barrel LANS and still fit in the magazine. I would like to shoot the Hornady 150/155/165/168 bullets and plan to use this rifle for home security, and hog hunting.

I appreciate the help!

Thanks!

Most reloading books will have a load for auto. Like 223 308 30.06. I have 7 different reloading books OLD and NEW. There is a little different in all of them.

 

[GW Staar]

The biggest difference on 308 vs. 7.62x51 is the rim thickness on the 7.62x51 is spec'd out slightly thicker by .01" to make the rim somewhat tougher for use in full auto weapons.

Also, you got the pressure backwards.

308 is rated for 62,000 PSI, 7.62x51 is rated at 60,200 PSI. The commercial 308 round is hotter than the military round.

Well, Trent there is a problem with me posting past my bedtime! I really screwed up what I was trying to get across. When I said, "You can load hotter in the 7.62X51 chamber than the .308....." I should have said, since 7.62 chambers are longer, you can conceivably load hotter by not pushing the shoulder back to ASCII specs. A dangerous pressure-spiking in the making. At least in the .308 chamber...the bolt won't close enough to release the firing pin. This is a reloading issue not a commercial or surplus issue....excepting the questionable foreign military brass you mentioned. Be aware, that if it almost closes and your trigger releases the firing pin....that's even worse trouble. It's always smart to test a head-spaced round before adding the parts that go "boom" in the gun, for that locking into battery issue, due to headspace or even base area diameter.

You are right, what I actually said was midnight-tired nonsense. But also consider that when talking pressure, remember that the commercial vs. the military data was incompatible, being that each used different methods of measuring pressure. The so-called 1800 psi difference is not definitive. Many "experts" have come to the conclusion that rounds loaded to military spec with their "CUP" data, and ASCII spec with their "PSI" data, actually are pretty similar in pressure. The difference is in the potential pressure decided by chamber size.

Sorry for the confusion. The key to not having a bad day at the range is learning to head-space correctly, and using tested, safe loads.

 

[Slamfire]

What your rifle will like will depend on the rifle.

A load used in NM competition for decades in M1a's is a 168 SMK 41.5 grains IMR 4895 LC cases, CCI #34, OAL LT 2.800". I would start at 40.5 grains and work up to 41.5.

Your velocities will be limited by your gas system, don't load hot. You have to live within the limitations of the gas system.

Do not seat bullets out to the throat, will cause more problems than solutions. I would not use any bullet heavier than a 175 SMK. Lighter is fine.

Use powders in the IMR 4895 burn rate. The advice for Garands/M1a's is probably equally good for your gas system, that is nothing faster than IMR 3031 and nothing slower than IMR 4064. Do not even try IMR 4350.

I would recommend using a small base die, set up that small base die with a Wilson case gage. I recommend pushing the shoulder back 0.003" or just size to gage minimum. Always full length resize, and regardless of die, set it up with a case gage.



Clean and ream to depth your primer pockets. Reaming is a good safety step as it ensures no high primers. High primers can cause slamfires in a gas gun if the anvils are seated and the primer cake is pushed onto the anvil.

I would recommend CCI #34 or Tula7.62 primers as they are less sensitive and are less likely to slamfire given that your rifle has a free floating firing pin.

 

[Trent]

Sorry for the confusion. The key to not having a bad day at the range is learning to head-space correctly, and using tested, safe loads.

Agreed.

The OP is a long time bolt gunner but a new gas system guy.

Since no one has covered how this might be different; my advice for him follows;

On a gas operated gun you really need to use small base dies to get it back in true spec. If you only have 1 gas operated autoloading rifle, then back in spec for your rifle is good enough (if your brass consistently lengthens .004" you might want to LEAVE it a little over-long to avoid overworking it, and forestall head separation). Be wary though if there's any bulging around the web from not being fully supported, you WILL need to small base size, period. (And then back off a smidge on your load....) Bulging shouldn't be an issue in an AR10 but I bring it up on general principal as it's a rule I try to adhere to on all gas operated firearms I'm reloading for.

It's not like a bolt gun where you can get by with neck sizing if you shoot that cartridge in the same gun. You might have a custom built bolt gun that has ZERO tolerance on a chambered round (great for brass life and accuracy). You won't see that on an autoloader, brass will expand lengthwise when fired because there is always a little "wiggle room" on the chambering.

If you only have neck size or full length dies for 308, GO BUY A SET OF SMALL BASE DIES. Right now. It'll save you a world of frustration.

This next part is really, really important.

If you have bolt guns in that caliber (308), KEEP YOUR LOADS MARKED AND SEPARATE. Keep your empty BRASS separate. I keep my brass segregated for each RIFLE; excepting 8mm, which I only have autoloaders for, so it all gets small base sized.

Semiautos are harder on brass; than a bolt gun; period. I don't care what platform it is, it's true. This is one of those rare "Trent Guarantees"!

So if you have bolt guns AND autoloaders in a caliber, buy some extra cheap plastic tubs to keep your stuff separate and labeled, and track it by generation. While you might be able to get 15 loadings of a piece of brass for your bolt gun, if you neck size, you might find you get only 3 or 4 out of an autoloader, which you should small base size. (Depends on how aggressive you are with sizing, your load strength, etc).

When the tattle tale bright ring starts to form ahead of the web on brass, pitch it (or recycle, but if you do crush the thing because savvy reloading people pick recyclers clean of firearm brass, just as sure as they do the floor of your range). Or, if you are really brave, at least buy a broken shell extractor and some spare parts for your bolt carrier group, because that head is about to come off under 50K+ PSI and ruin your day. Another Trent Guarantee.

As far as specific load data, Slamfire has great advice there. I would try to stay mid range burn rate, with ~168 grain projectiles. Don't push 180's with a slow powder, you'll put you gas system under loads of extended, undue pressure and foul the heck out of your action with carbon. Don't push light rounds with a faster powder exceptionally hard, for the same reason, it'll cause violent cycling. REALLY hard on parts. You'll have FANTASTIC reliability and excellent feeding, right up to the point your bolt snaps in half from the stress. (Don't ask me how I know lol)

Think that's all the tips I have on autoloaders vs. bolt guns.

If I remember or think of anything else I'll add to this later.

 

[moonzapa]

Thanks everyone for the excellent information and advice. I purchased a small base die from Forster and will use IMR-4895 powder to begin with. I most likely will use 125-150 grain slugs. I have 300 rds of Lapua brass that I will begin to work up. The primer pockets seem to be the best I have ever seen, but I will still check them out. I also purchased a .308 Win headspace gauge from Lyman. Would have liked to have gotten a Sinclair but this one was available. A friend of mine is getting ready to do the gas gun venture. I will make sure he knows the big difference in loading a bolt gun as opposed to a gas gun....big difference in characteristics. Good Shooting!!!!

 

[popper]

Moonzapa - make sure you use the case gauge and push the shoulder back to spec at first. Or get a rubber hammer to beat the bolt open. Check your fired brass in the gauge to see if you can increase HS to a safe amount. Match bullets are that - target ammo. They may shatter on a pig. Try the Amax (168 which is a hunting bullet). I'm shooting MOA @ 2400 with 165 gr cast in my 16" carbine, Amax does the same. IMHO, your weight choice is too low, both of mine work best @ 165ish, as with most comp. target shooters.

 

[Walkalong]

set up that small base die with a Wilson case gage. I recommend pushing the shoulder back 0.003" or just size to gage minimum. Always full length resize, and regardless of die, set it up with a case gage. ........................................Clean and ream to depth your primer pockets. Reaming is a good safety step as it ensures no high primers. High primers can cause slamfires in a gas gun if the anvils are seated and the primer cake is pushed onto the anvil.

Agreed. I like the K&M primer pocket reamers. A superior quality tool.

 

[moonzapa]

I loaded 10 rds for my AR-10 last night. I used a Lyman .308 Win headspace gauge, and read the directions thoroughly; I used a Forster small base die to resize new Lapua .308 Win brass; I loaded 40.5 grains of IMR-4895 powder and utilized Winchester WLR primers and I ensured the primers were seated slightly below the end of cartridge; I loaded the Hornady 168 A-Max bullets at COL: 2,800".

I'm thinking about buying an RCBS taper crimp die to prevent bullets from receding after recoil and getting the Dewey AR barrel cleaning link.

Thanks Trent and everyone for getting me on the straight and narrow.

 

[tygranch]

The current issue of Guns and Ammo has a good article on loading for the AR 10. Pretty much duplicates what was said here as far as bullets and powder. Using a small base die and a precision mic are great advice.

 

[popper]

Moonzapa - get the Lee FCD for crimp. Works great. You should be shooting ~ MOA @ 100 with that load. You will need the chamber wire brush and any decent cleaning rod will do. You wight look into the BCG carbon scraper - I haven't needed it yet - a screw driver works fine. COL is hard to measure with the sofpoints. I adjust to just keep from engraving, lock the die down with the Hornady lock rings.

 

[moonzapa]

Popper:

thanks for info about the Lee Crimp die!

 

[Ky Larry]

In over 40 years of reloading, I have yet to find a shortcut to finding accurate loads. Every gun is a study in accuracy unto itself. This means trying lots of different combos of powder,bullets,and primers and fine tuning. Keep good records. Your rifle will tell you when you get it right. Good luck.