So I've finally got my AR-10 project juuuuuuuuust about finished. Need a base for my scope, but then it's off to the races.

I have a die setup for .308, but am I right in assuming that I'll need to get a small base die for the AR-10?

I also assume that I can use whatever seater die I want, right? I'm interested in getting a micrometer one.

Also, any suggested loads for the AR-10, esp. OAL specs? Barrel is an 18" Rainier Arms Ultramatch (mid-length gas), FWIW.

It's been ages since I reloaded anything, so I guess it's time to dust off the press and dies for this beast.

I'll answer what I know,small base for auto loaders,now that bullet thing I rely on dial calipers[don't like the scarret electronic I have]
Bullet oal are usually same in length but other measurement can vary as being produced with mass production even in same box,hence calipers.
Never loaded that caliber,but most others I have over the decades mostly for hunting and plain old target practice fun.

I load for 5 AR's and none of them require SB dies. You do need to push the shoulder back 0.002-0.003" for reliably feeding. All of my AR's have adjustable gas blocks, for I can tune the gas system so it's not over gassed. If your pulling the brass out under too much pressure you will really stretch it, causing premature brass failure.

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I load for 5 AR's and none of them require SB dies.

I use standard 308 dies for my M!A's and Garand's in 308.

But when it came to the Sig 716, I was forced to get SB sizing die to get satisfactory functioning.

The majority of semi-autos have larger diameter chambers. So I would start with a standard die and get a small base die if you have extraction problems.

A small base die will reduce the cases to minimum SAAMI dimensions. Meaning reduce the case diameter .002 to .003 and push the shoulder back .002 to .003 more than a standard die.

In a AR10 or M1A the resized case should be .003 to .005 smaller in diameter than its fired diameter. This allows the case to spring back from the chamber walls and extract reliably.

Chambers and dies vary in size, example I have a standard Lee .223 die that will size the cases smaller than my RCBS small base die.

Bottom line, I would start with a standard full length die if you are only using brass fired in your rifle. If you plan to buy once fired brass or use range pick up brass you may need a small base die. This is because after sizing the case will try to spring back to its fired size. And this can cause a problem if the cases were fired in another chamber.

For powder I’d look at Ramshot TAC or the 4895 burn rate area.

I should add all of my AR's have min spec chambers which are very tight. A lot of the std length recommended OAL does not work for it's into the rifling in my guns. And I do it all with std base dies. The SB dies size the base of the die down 0.001-0.002" more. I'm also using Redding Type S Bushing dies. I anneal my brass every cycle so I'm not dealing with brass that does not have a lot of spring back.

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Barrel is an 18" Rainier Arms Ultramatch (mid-length gas), FWIW.

I have one of these I reload for.
Going to have to look up what I did and get back to you.
I measured my chamber and did multiple test shots.
FWIW, the OAl was quite a bit less that my load for my Rem 5R.
I shoot the same load in my 16, 18m and 20 (have MA TEN's with one of each) Ultra Match rifles too all the chambers were pretty close.
YMMV

OK just checked.

Varget 43.0gn
SMK 168
OG 2.229
OAL 2.808

I may have some other load data - will look.

For range blamo, I like 168gr Hornady BTHP, in front of 44gr of RL15 in LC brass.

I get better groups with 168 AMAX, 175gr TMK, and 190gr CC, magnum primers and premium brass. Examples below...

44.6gr RL15, 168gr AMAX and Federal Brass.
44.4gr RL15, 175gr TMK and Lapua Brass.
43.4gr Varget, 175gr TMK and Lapua Brass.
39.9gr RL15, 175gr TMK and Starline Brass.
40.3gr RL15, 190gr CC and Federal Brass.

Thanks for the data, folks.

Just got my scope mounted and zeroed on Friday and started pulling the reloading gear out of mothballs last night.

I've got some Varget and some SMKs left, so I might start there before I go out and buy anything new.