Short Range AR10 Caliber for Accuracy

[Phil3]

What caliber would give the best accuracy at 300 yards and under for an AR10? The 308, 260 Remington, 243, or...? I would shoot longer distances, but no place nearby to do that. Looking for tightest groups. Not sure the 308 gives up anything at these ranges, other than more recoil. ??? Will always be reloading my own.

- Phil

 

[Shooter21]

Re: Short Range AR10 Caliber for Accuracy

AR 15 in standard 556 with a 7 twist Daniel Defense hammer forged barrel and some tlc will give you anything you want way beyond 300. but for AR10, go with a 308

 

[armydog]

Re: Short Range AR10 Caliber for Accuracy

ether will take a Zombie out under 300 yds ands 5.56 will be cheaper and have less recoil.

 

[ORD]

Re: Short Range AR10 Caliber for Accuracy

In the AR-10...the .308 will be cheaper to shoot (unless you reload for it and then its likely a close call between all those cartridges depending on the pills you push). As for accuracy...all things being equal, I don't think that you'll find any one of those cartridges "more" or "less" capable of outstanding accuracy than any of the others. 99% of it comes down to whether YOU are capable of getting the most out of any one of them and whether your rifle is built to deliver the best accuracy possible or if it is simply a downrange lead delivery system built to put bullets in the general direction of the target.

However...I'm with the others!! Why not just stick to the AR-15 in 5.56/.223?? Excellent accuracy and power within 300yds and VASTLY cheaper to shoot than any of the AR-10 calibers you referenced.

 

[rcw3]

Re: Short Range AR10 Caliber for Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Phil3</div><div class="ubbcode-body">What caliber would give the best accuracy at 300 yards and under for an AR10? The 308, 260 Remington, 243, or...? I would shoot longer distances, but no place nearby to do that. Looking for tightest groups. Not sure the 308 gives up anything at these ranges, other than more recoil. ??? Will always be reloading my own.

- Phil </div></div>

Without question if you are looking for the best AR-10 accuracy, run with the 243 Win. among the cartridges you have listed. Recoil plays a big factor in AR-10 accuracy (all receivers and the whole platform is Aluminum, and it's a push pin rifle, the more the recoil, the more the flex and yield in the whole set up) so go with the cartridge that puts the least amount of recoil and stress on the platform. Not even debatable when it comes to AR-10 accuracy. A lesser recoiling cartridge is also ergonomically easier to shoot (i.e. throws you off target less with each shot, much less rifle jump and twist when you touch off a round).

Since you will be reloading, .243 brass is cheap (Winchester brand is great for AR-10's) and great 6mm bullets are plentiful and inexpensive relative to 6.5 mm and 308 bullets. An 8" twist barrel will allow you to run the 105-108 gr class of bullets which will just about beat anything B.C. wise at 0 - 600 yards, especially considering the speeds you can easily run them at (2900 - 2950 fps without breaking a sweat), and if your game for tinkering with the 115's, you should run a 7.5" twist.

Robert
www.6mmAR.com

 

[Phil3]

Re: Short Range AR10 Caliber for Accuracy

Good question. I already have an AR15 built for the same distances. The parts important for accuracy include the Krieger 22" 1:9 bull barrel chambered for .223 and Geissele 2 stage adjustable trigger. Can shoot 5 shot 1/2" groups at 100 off a bipod with PMC ammo.

So why an AR-10? I dunno, I just wanted one (and still do), and bought a Noveske N6 lower receiver during the craze. I have the Armalite upper receiver (one without FA...my preference), mags, LPK, bolt assy, and few other small parts. Planned on a Krieger barrel and JP Rifles single stage trigger (I like these over 2 stage I think).

The .243 is a possibility, but according to www.6mmbr.com, barrels last as long as 1500 rounds vs 5000+ for a 308, with a 260 somewhere in between. At $500 for a Krieger barrel and chambering, that is pretty pricey per shot. On the other hand, like the AR15, I want to see how close I can get to drilling bugholes with a gas gun, and the 243 may be optimal for that, due to recoil and inherent accuracy of the round. If Robert or others can speak to barrel life, would welcome those comments.

- Phil


<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">However...I'm with the others!! Why not just stick to the AR-15 in 5.56/.223?? Excellent accuracy and power within 300yds and VASTLY cheaper to shoot than any of the AR-10 calibers you referenced.</div></div>

 

[BCP]

Re: Short Range AR10 Caliber for Accuracy

Go 308. There's lots of stuff I was going to type up but I'm wore out from dealing with an idiot homeowner so if you want to hear a bunch of reasons I'll post them up later.

 

[Phil3]

Re: Short Range AR10 Caliber for Accuracy

Would welcome your comments, and wish success with the idiot problem. Thank you. - Phil

 

[ORD]

Re: Short Range AR10 Caliber for Accuracy

Damned idiots!!! I sympathize, BCP!!!

There is a lot of that going around today (not in any way directed at the OP or anyone else in this thread)!

 

[rcw3]

Re: Short Range AR10 Caliber for Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Phil3</div><div class="ubbcode-body">

. . .

The .243 is a possibility, but according to www.6mmbr.com, barrels last as long as 1500 rounds vs 5000+ for a 308, with a 260 somewhere in between. At $500 for a Krieger barrel and chambering, that is pretty pricey per shot. On the other hand, like the AR15, I want to see how close I can get to drilling bugholes with a gas gun, and the 243 may be optimal for that, due to recoil and inherent accuracy of the round. If Robert or others can speak to barrel life, would welcome those comments.

- Phil
</div></div>

Phil

There's no free lunch - you want the accuracy and performance, you have to pay the price somewhere, it's that simple. The first posting did not suggest barrel life was your focus. The one thing I can say about 243 Win AR-10's , and I shot them in high power competitions for a number of years, is it helps barrel life a lot not to run with full throttle hotter loads (milder to moderate is best). If you run the 105-108 gr bullets down around 2800 - 2900 fps, you can get 2250-2500 rounds out of a barrel with very excellent accuracy as well, also provided you do not hammer a lot of rounds down the pipe all the time in quick succession. Rapid fire work is a killer for barrel life no matter what the cartridge.
Robert

 

[Phil3]

Re: Short Range AR10 Caliber for Accuracy

Robert,

Understood on no free lunch. But do want to get an idea of the cost of the lunch. I have no interest in rapid fire shooting or running hot loads. For the distance I am shooting, at paper, mild loads should be fine, unless the rifle seems to "like" hotter loads. And that brings me to my next question. Is there any gas tuning that needs to be done to use the 243? Is there an optimal barrel length for this round? I don't suppose I would need a muzzle brake for this caliber in an AR10. I ask not because recoil is a huge issue, but because light recoil can help achieve my best accuracy. My selection of calibers is not necessarily limited to the ones I mentioned. I should have stated I am open to any caliber that is found to be very accurate in the AR10.

Input on my selected components for this AR10 are welcome.

- Noveske N6 lower receiver
- Armalite upper receiver
- Armalite bolt assy
- JP Rifles freefloat handguard (have on my AR15 & like it)
- Geissele 2 stage adjustable (used in AR15 and like it, but may consider JP Rifles single stage)
- Krieger bull barrel (length, twist to be determined)
- Evolution Gun Works gas block (clamp on, works on my AR15)
- Stock A2 stock (works for me on AR15)
- Armalite scope mount (lower than most, suits me)

I would expect this should shoot pretty accurately. I have already checked runout on upper receiver barrel face (~.001"). Fit of upper and lower receiver is tight.

- Phil

 

[sinister]

Re: Short Range AR10 Caliber for Accuracy

The .243 is notorious for being a throat burner. The .260 is finicky in the AR-10.

A cut-rifled barrel in .308 will give you excellent flexibility, great accuracy potential, throat longevity, and decent economy.

If you are limited to 300 yards you have a wide variety of really great bullets to select from.

The 135 Sierra Match King is a good choice without abusive recoil or bucking. Other good, light bullets (including flat-bases) also have superior short-range potential.

Good luck.

 

[BCP]

Re: Short Range AR10 Caliber for Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Phil3</div><div class="ubbcode-body">Would welcome your comments, and wish success with the idiot problem. Thank you. - Phil </div></div>

Rich prick's trophy wife with a chest worth more than my truck, all my guns and all my tools trying to screw me out of 500$.

You won't get any more accuracy out of a 243 or 260 at those ranges with a run of the mill AR10 and your barrel will wear out faster. That's why I say 308. As long as you take care of it and don't do anything stupid like bump firing it a hundred times your barrel will last forever.

Your parts list looks fine, just keep in mind a bull profile will be really heavy so when you do order your barrel call up whomever you are getting it from and tell them what you want to do with the rifle. They will be able to give you more input to keep you on the right track.

 

[smgrendel]

Re: Short Range AR10 Caliber for Accuracy

AR-15, 6.5 Grendel.

 

[longshotbml]

Re: Short Range AR10 Caliber for Accuracy

Everyone's definitiion of "accurate" is different. If you're desire is one hole groups at 300 yards don't bother with the AR-10. My Armalite AR-10T will shoot honest 2.5 inch (edge to edge) 10 shot groups at 200 yards with Federal GMM. That's from the magazine fired at a rate of 20-30 seconds per round. At the distance you're shooting all the calibers will work fine. I like easy and the .308 gives you lots of options.

 

[BERTMAN77MK2]

Re: Short Range AR10 Caliber for Accuracy

have you considered the 6.5x47? or the 6.5 Creedmoor?
some of the teams at sniper comps (read WINNERS) use the Creedmoor---I read that the 6.5X47 is a world record holder in 300 meter comps for which it was designed--and both are 1000 yd
competitors---not sure if anyone chambers the 6.5X47 in AR10

 

[rcw3]

Re: Short Range AR10 Caliber for Accuracy

You can run a 6.5 x 47 Lapua out of an AR-10 without problem. I would stick with the 120-123 gr bullets out of that cartridge as it's a little short on capacity for the 139-142 gr. bullets.

The only thing I am not crazy about with the 6.5 Creedmoor is that Hornady's brass tends to be a bit on the softer side and that is not really ideal for AR-10's or semi autos that extract under pressure.

 

[rcw3]

Re: Short Range AR10 Caliber for Accuracy

Phil

On barrel weight, with an AR-10, for accuracy, a "meaty" barrel is definitely a plus. If you are using an EGW clamp-on gas block, the biggest they make is .936" so that would be your gas block diameter. Forward of the gas block to the muzzle you can realistically run maybe .920" - .930", and behind the block you need to stay about 1.025" for a while in order for the gas tube to stay clear of the barrel (unless you are going to take a ball end mill and put a groove in the barrel for the gas tube to sit in).

About the heaviest contour I felt I could do (with something like the EGW .936" clamp on block) without having to do some "trick" stuff to make things work out is a 3" long breech section 1.2" dia., then tapering over the next 2.5" to 1.025" dia. and staying striaght that way to the gas block, then stepping down at the gas block area to .936", then stepping down after the gas block and out to the muzzle at .920" - .930".

 

[Phil3]

Re: Short Range AR10 Caliber for Accuracy

Robert,

Thanks for your reply. I am open to other gas blocks, but like the even pressure the clamp-on style applies to the barrel vs the set screw type. May make no difference, but doesn't hurt either IMHO.

Krieger says the gas block diameter of the AR10 barrel is .937", while the muzzle diameter is .900", which surprisingly, is less than the .920" on the AR15 bull barrel. I don't know what the diameter is between the gas block and the receiver. I will ask Krieger about that. I would consider other barrels as well, if they are known to shoot as well or better than the Krieger..and are available.

- Phil

 

[rcw3]

Re: Short Range AR10 Caliber for Accuracy

Phil

We get pre contoured blanks and make things up from there and from that perspective Krieger and others will make up whatever we send over as the contour drawing. I assume you are speaking of a canned AR-10 barrel contour Krieger offers.

 

[rcw3]

Re: Short Range AR10 Caliber for Accuracy

On the .936" vs .937" gas block issue, the true real dimension of the interior of the .936" gas block is typically .9375" (i.e. 15/16") minus a little bit for anodizing, so they call the gas block a .936" so people will turn the gas block section on the barrel down to .936" and there will be enough clearance so the block fits over that section of the barrel without having to jam or hammer the block on. With a clamp on block, the clamping provides an excellent no stress seal (especially if there's only .001" or so diameter difference between the inside of the gas block and the outside of the barrel at the gas block). The worst situation is where someone turns the gas block section of the barrel a "fat" .9375" and the block (because of anodizing build up) is .937" and then you cannot easily get the block on or off - no need for that!

 

[BCP]

Re: Short Range AR10 Caliber for Accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Phil3</div><div class="ubbcode-body">I would consider other barrels as well, if they are known to shoot as well or better than the Krieger..and are available. </div></div>

Between a rock or hart or lilja or krieger etc barrel the difference will be the guy pulling the trigger.

I don't think you can go wrong with a krieger but don't discount other makers out there as all of them are very good.

 

[Phil3]

Re: Short Range AR10 Caliber for Accuracy

Robert,

I wish I had your ability to work with precontoured blanks. I have a lathe (Southbend 9" 4-1/2 ft bed), but not big or accurate enough for that kind of work. Hence, I am confined to whatever a manufacturer sells and can customize for me.

One thing I always wondered about, and maybe you can speak to. Is there any valid concern about how much of a lever arm and potential distortion in the upper receiver that may result from having a heavy bull barrel hanging off the end of the aluminum receiver? If so, it seems to me a shorter but stiff heavy barrel would be good, especially if I don't need the extra velocity a longer barrel would afford.

Krieger says ".937" for the gas block, but it is not clear if that is the barrel diameter or the barrel is machined to accommodate a .937" I.D. gas block. Krieger says the same thing for the aR15 barrel, and the EGW gas block fit onto that barrel very nicely.

- Phil

 

[pawprint]

Re: Short Range AR10 Caliber for Accuracy

GAP's offering Guarantees you 3/4MOA, nothing else to do, but buy their rifle.

 

[BERTMAN77MK2]

Re: Short Range AR10 Caliber for Accuracy

OBR's have a good track record in the accuracy dept also

 

[Phil3]

Re: Short Range AR10 Caliber for Accuracy

Simple enough to be sure, and I really like their rifles, but their AR-10 is not exactly what I want, as it includes standard equipment and options which are not my first choice. Further, they would have to sell the rifle installed with a "bullet button" kit (tip of a bullet can be used as a tool to detach mag), as well come with mags that can hold 10 rounds max in order to ship to California. They may be able to do this but a moot point, if their configuration is not what I am after.

- Phil<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: paw print</div><div class="ubbcode-body">GAP's offering Guarantees you 3/4MOA, nothing else to do, but buy their rifle. </div></div>

 

[VKC]

Re: Short Range AR10 Caliber for Accuracy

For AR10 platform, I would choose 308win since it is the standard. Easiest to find loaded match ammo, and also plenty of choices for reloading. The reliability is best, as AR10 was intended for that caliber.

However, if you want better accuracy for more expense, with better barrel life than 243Win, then I would choose 6.5 Creedmoor. In general, less trouble than 260Rem in semi-auto platform. Hornandy makes match grade loaded ammo. If you reload, 6.5 bullets have better ballistics than 308win.

 

[9mmkungfu]

Re: Short Range AR10 Caliber for Accuracy

To 300 yards? .308 of course.

 

[Force_Multiplier]

Re: Short Range AR10 Caliber for Accuracy

an AR 15 in 5.56

 

[Sulenski]

Re: Short Range AR10 Caliber for Accuracy

meh I will put another vote in for .308 for the simple reason I love to shoot it and its a very plentiful round that is not so harsh on barrel life.

 

[Rovieairto]

Re: Short Range AR10 Caliber for Accuracy

The 308 is an inherently accurate, and efficient cartridge.
It does very well in shorter barrels.
Ar's get a little unwieldy with long barrels so I'd get a 16"-20" Kreiger in 308 and enjoy.

Lighter, flat based bullets, should give excellent accuracy with modest recoil out to 300.

I shoot my 18.5" out to 1k and it's still ss with 155's.
I wish I had put a 16" barrel on it as I would only have given up less than 100 yards.
My opinions.