Need help with AR10 260rem reloading

[hogan]

I'll go ahead and toss in my experience, my lr-308 loves H4350 and I don't have an adjustable gas block, and I use federal 210M (6.5 creedmoor). My 308 load development for a different -10 platform was very different. Your mileage may vary, and expect to try multiple variations and allow your data to point you in the correct direction. Gas guns show different signs than bolt guns, so more information on what to expect is a good thing.

-Mac

Here is the deal.... Armalite rifles (ALL AR-10 & 15s) are designed to function with moderate burning rate powders. Varget, RL-15 IMR 4064/4895 Maybe 3031, but it could be a tad "fast". There are other excellent powders as well, VV and Accurate 4064/2230, plus Hodgdons.

Bolt rifles are not Dwell-time sensitive. The pressure impulse of the load means nothing in a bolt gun since it is not used to cycle the bolt carrier and extract, eject and load the next round. Faster powders give less dwell time, slower powders increase it. Faster powder likely "safe" in your rifle; just not going to function as smoothly.

Slower powders are dangerous. Pressure continuing to build for greater duration than optimum. Maybe if you are shooting XMR4350, which is the fastest of the three 4350s; MAYBE you are okay using it; but for what purpose? The risk is battering your bolt carrier, buffer setup, bolt lugs and barrel extension. Nothing "Good" is gonna come out of that. Just because the 4350 load "performs" don't mean your AR "likes it"...

Armalite does not warrant their rifles when used with handloads. Here is why... Lack Of Awareness and Understanding.

Sierra used to include a lot of articles by men like David Tubb and Gary Anderson. Legendary shooters who have forgotten more about handloading and marksmanship than any gun magazine writer will ever realize existed. There were articles on Gas Gun Loading and Service Rifle applications. What worked in 1985 for the M14/M1a .308win rifle is still valid for the AR-10. Talking the 168 BTHP match bullet with IMR4064 or 4895. No Varget or RL powders available back then. Need to look at updated info, but those powders are still excellent for that bullet, just some like Varget are maybe less temperature sensitive.

To safely shoot your gas-operated semi-auto rifle you MUST Understand the variables and Cyclic Functions.
There is no "pressure sign" loading for these weapons unless you have no regard for your safety or that of others, or the longevity of your gear.

 

[jdj71]

While it deals with 308 Win, I highly recommend reading the article Lane Pearce wrote for the Hodgdon 2014 Annual Reloading Manual: "Reloading the 308 Winchester for ARs". He discusses problems encountered and solved in tuning loads and preparing cases to ensure proper functioning in the direct-impingement AR-10 (as well as getting good accuracy.) Apparently the AR-10 is not quite as slap-dash easy to reload for as the AR-15 in 223 Rem. I wouldn't know, but I did find the article to be comprehensive and very informative. FWIW.

good advice

 

[jlow]

I have both an AR-10 .308 and a bolt action .308. The advantage of the AR-10 is you have 20 rounds on call. The disadvantage is the mag length you are forced to deal with unless you are willing to do single load.

The mag length limitation significantly reduce the COAL of the loaded round which means the bullet is seated much deeper, reducing case volume which reduce the amount of power you can put in the case but most importantly the pressure you will face with an equivalent amount of powder.

This always result in significant higher chamber pressure which limits the amount of powder you can use, and MV you can achieve. It also significantly reduce the life of your brass as the primer pockets will loosen up sooner and yea, ejection will also bang up your expensive brass.

As others have said, shooting a 6.5 in an AR-10 you will be loosing out a lot on the advantage of this cartridge due to limited MV and yea the short barrel of the AR-10 does not help either.

It is neither good or bad, just depends on your priorities.

 

[mic2377]

I will say that the AR platform is much more tolerant of alternative burn rates that other platforms. The M14/M1a comes to mind with its less than robust op rod.

The AR platform can also be "tuned" at least somewhat to deal with altered pressure curves - think different buffers, adjustable gas blocks, etc. If there was any detriment to slower burning powders, is that AR's shooting these tend to be harder on brass.

I don't think H4350 is completely out of the question. I plan to focuse my load workup on 120-130 gr bullets as feel brass life and recoil will be optimal, but lots have had success with 140's and H4350.

 

[hogan]

Hey guys,

I picked up a custom AR10 upper in 260 rem. From the research I did so far, most people use h4350 and 123 grain bullets in semi auto.

Can someone please tell me where I should start with H4350 and 123 grain bullets in AR10?

Also, which buffer tube/spring should I use?

Thanks!

Probably said many times already, but..... NO USE slow powder in autoloader.... 748, 4064, Varget, RL15, etc

Why use the light bullets? Purpose of the .260 is flatter trajectory, Looking for 140/142gr bullets w/high BC.

 

[Shynloco]

The AR platform can also be "tuned" at least somewhat to deal with altered pressure curves - think different buffers, adjustable gas blocks, etc.

Good thinkin!

......I plan to focuse my load workup on 120-130 gr bullets as feel brass life and recoil will be optimal, but lots have had success with 140's and H4350.

mic,
A good friend (and one of my Gunsmiths) built himself a custom AR10/260 that shoots EXTREMELY accurately using 123 Sierra's being push by VVN150. And he's been doing extremely well in competition for 600yd - 1K using that combination. Might want to consider giving it a try since you are leaning toward the 120-130 bullet weight class. BTW, he hasn't tried 130's, but why bother when you are beating all others with what you have. And don't think for a second those 120's don't shoot despite the fact that 14o's do nicely. BTW, there IS a world of difference between what shoots in an AR10/260 and a Bolt Gun .260.

Alex