AR-10 Work Well w/6.5 x 47 Lapua?

[Phil3]

I have some AR-10 parts I got many years ago (i.e., Noveske N6 lower, etc.), but never got around to building. I was going to do the project in 308, but like the 6.5 x 47 much more. I wonder how well it would work in an AR-10. It runs a bit higher pressure than a 308 and has a small rifle primer.

Phil

[sigstroker]

Why not go 6.5 Creedmoor? Barrels, etc are widely available. What does 6.5x47 do different?

[C.G.]

No direct experience but it should work just fine. Not sure about of the shelf parts availability for it, as mentioned by Sigstroker, 6.5 Creedmoor is more common and Armalite used to sell Creedmoor uppers, don't know if they still do.

[Phil3]

Why not go 6.5 Creedmoor? Barrels, etc are widely available. What does 6.5x47 do different?

Good and fair question.

I thought about the 6.5 Creedmoor, and it is a good round to be sure. Little can be taken away from it. The things I took note of when I chose to use the 6.5 x 47 Lapua for a bolt gun (and an AR-10), were these...compared to the 6.5 Creedmoor.

1) Less case capacity should help barrel life (less powder burned).
2) Slightly longer case neck allowing a bit more room to extend bullet out when chasing lands.
3) Slightly shorter case allowing a bit more room fitting into magazines.
4) Designed for 300 meter competition. This is a distance I like.
5) Uses small rifle primers (Creedmoor did not when I selected 6.5 x 47 for the bolt gun).
6) Better competition track record. I may be wrong on this!
7) Seems less fussy with loads. I have read this, but not sure if true.
8) Uses around 10% less powder (as best as I recall). Cuts round costs slightly.
9) Anecdotal evidence indicates more often than not, superior accuracy, however slight.

Having the 6.5 x 47 in a bolt gun and the AR-10 means not having to buy supplies for two calibers (6.5 x 47 and Creedmoor).

Since I only reload, off-the-shelf Creedmoor ammo is of no value to me.

Phil

[C.G.]

Good and fair question.

I thought about the 6.5 Creedmoor, and it is a good round to be sure. Little can be taken away from it. The things I took note of when I chose to use the 6.5 x 47 Lapua for a bolt gun (and an AR-10), were these...compared to the 6.5 Creedmoor.

1) Less case capacity should help barrel life (less powder burned).
2) Slightly longer case neck allowing a bit more room to extend bullet out when chasing lands.
3) Slightly shorter case allowing a bit more room fitting into magazines.
4) Designed for 300 meter competition. This is a distance I like.
5) Uses small rifle primers (Creedmoor did not when I selected 6.5 x 47 for the bolt gun).
6) Better competition track record. I may be wrong on this!
7) Seems less fussy with loads. I have read this, but not sure if true.
8) Uses around 10% less powder (as best as I recall). Cuts round costs slightly.
9) Anecdotal evidence indicates more often than not, superior accuracy, however slight.

Having the 6.5 x 47 in a bolt gun and the AR-10 means not having to buy supplies for two calibers (6.5 x 47 and Creedmoor).

Since I only reload, off-the-shelf Creedmoor ammo is of no value to me.

Phil

All good points, especially since you already have the bolt gun.

[sigstroker]

Good and fair question.

I thought about the 6.5 Creedmoor, and it is a good round to be sure. Little can be taken away from it. The things I took note of when I chose to use the 6.5 x 47 Lapua for a bolt gun (and an AR-10), were these...compared to the 6.5 Creedmoor.

1) Less case capacity should help barrel life (less powder burned).
2) Slightly longer case neck allowing a bit more room to extend bullet out when chasing lands.

Doesn't matter in an autoloader because your ammo still has to fit in the magazine.

3) Slightly shorter case allowing a bit more room fitting into magazines.

I haven't heard of anyone having trouble with 147 gr CM ammo in magazines.

4) Designed for 300 meter competition. This is a distance I like.

Are you seriously going to use an AR in 300 yard competition?

5) Uses small rifle primers (Creedmoor did not when I selected 6.5 x 47 for the bolt gun).

You're going to have a bit of a problem either way with firing pin size. If that doesn't turn out to be a problem, just buy 6.5 CM small primer brass. It's out there.

6) Better competition track record. I may be wrong on this!

Again, competition with an AR? I assume you mean bullseye.

7) Seems less fussy with loads. I have read this, but not sure if true.

Maybe, but Masterpiece Arms guarantees 3/8ths moa with Hornady factory ammo, so they can't be that bad.

8) Uses around 10% less powder (as best as I recall). Cuts round costs slightly.
9) Anecdotal evidence indicates more often than not, superior accuracy, however slight.

I doubt you can notice in an AR.

Having the 6.5 x 47 in a bolt gun and the AR-10 means not having to buy supplies for two calibers (6.5 x 47 and Creedmoor).

Since I only reload, off-the-shelf Creedmoor ammo is of no value to me.

Phil

You have to buy CM brass. Bullets, primers, and probably powder would be the same.

The gunsmithing costs of having a custom chambered barrel will likely far outweigh any tiny cost advantage of reloading.

[Phil3]

Hey sigstroker,

Thanks for all the comments. A few questions and comments.

One, no the AR-10 would not be used in competition. I only mentioned use of the rounds in competition because I am interested in accuracy and it seems like the 6.5 x 47 is more favored vs the 6.5CM. I am shooting only at paper targets, or maybe steel once in a while.

I did not understand your first comment about fitment in a mag. I was trying to say that because the 6.5 x 47 is slightly shorter, it leaves me slightly more room in the mag to keep extending bullet out (chasing lands due to wear), before the bullet gets so far out, it will not fit in the mag.

I have read of some instances where people ran into CM rounds that would not fit in the mags of BOLT guns, but of course that depends on the loaded round and perhaps an AR-10 mag has more room than a bolt gun. I am using an AR10b variant which uses Armalite proprietary mags. I measured one and it can handle an absolute max of about 2.85" round length. I think most CMs will fit that, but not sure.

Yes, Lapua does make small primer brass, but it is expensive and the ONLY brass for 6.5 x 47. I have to check to see cost on CM brass, but at least there are choices, and some of it is far cheaper than 6.5 x 47 Lapua brass. This is an issue since I expect the AR-10 to beat up on brass and not allow it to last long.

Krieger will make a barrel chambered in 6.5 x 47 Lapua or 6.5CM to my specs for $535. As long as I send them the Armalite bolt and use an Armalite upper receiver (I have both). I have not searched around for an aftermarket AR-10 barrel, but I did not think $535 was too unreasonable for a barrel in the length, twist, and finish I want. That does not include a gas block or threaded muzzle.

I am still considering just moving to 6.5CM completely, for the AR1- and bolt gun, just so I can devote time and energy to one caliber and avoid extra expense and trouble with both the 6.5 x 47 and 6.5 CM. Even some of the most ardent supporters of the 6.5 x 47 Lapua do say the CM is pretty good.

Phil

[sigstroker]

You might send them your whole upper so there's no misunderstanding as to "AR-10", to make sure the gas port, front sight cuts, etc are all in the right place.

[C.G.]

Lapua brass is more expensive, but you will get more reloads out of it, so it evens out in the long run.

[Phil3]

Any tips on how to make brass last longer in an AR-10...or any AR for that matter?

Phil

[Phil3]

You might send them your whole upper so there's no misunderstanding as to "AR-10", to make sure the gas port, front sight cuts, etc are all in the right place.

I won't have front sights, but since there are AR-10 variants around, I think you are right to send them not only my bolt, but also the stripped upper, just to make sure of no confusion or mistakes.

Thanks.

Phil

[C.G.]

Any tips on how to make brass last longer in an AR-10...or any AR for that matter?

Phil

You are on the right track with Lapua brass. I still haven't come to the end life of my 6.5 Grendel or .338 LM brass. In case of the 6.5 Grendel, I am told that you can get 8 reloads out of Hornady brass and 20+ out of Lapua.