AR with 22" barrel- 6,5x47Lapua or 260Rem?

[JL]

Ok, would need a second opinion here.

After thinking it for quite a while, I have already decided that next barrel for my 7.62 AR will be 6.5mm/.264.
Also, during years I have came into conclusion that 22" is maximum barrel length for me personally.

With these conditions, I have narrowed my options to 260 and 6.5x47. But I´m still bit unsure which would work actually better in practice. At this point, I´m already almost certain that 47 Lapua is right choice for me. Here´s my list, feel free to disagree if I got something wrong.
Before that, I would like to point out that brass price, cartridge availability or anything related to reloading costs doesn't matter to me. At this point I´m only interested about practical LR performance and accuracy.

TIA!

47L:

+ "Easy" caliber what comes to pure accuracy? All rifles I personally know shot well right away without massive load developments
+ Small capacity brass with higher max. pressures basically evens up smaller charge compared to 260.
+ Small primer means no chip in brass base even with hotter loads (Noticed this with small primer 308 Palma´s)
+ should work with autoloaders as fine as 260 do
+ Slightly smaller and lighter cartridge to carry (practical usage)
- ?

260
+ Lapua brass now available
+ Bigger case capacity (which doesent help with 22" barrel?)
+ Perhaps bit higher MV:s? (difference still negligible?)
+ ?

- Short 7.62 AR magazine COAL means in practice that its not as straight forward to make shoot well than 47L?
- ?

 

[daxromana]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

Hmm. That is a good question. I would lean toward the 6.5 x 47L

-Much more room in the magazine to play with seating depth. You will be able to seat bullets out farther with any throat erosion.
-Small primers will mean more reloads and more consistent ignition (should have slightly better ES and SD)
-Speed is close enough to the 260 that it is a non issue

Who is chambering big gas guns in 6.5 x 47?

 

[jbailey]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

I thought about doing a 6.5x47L gas gun, as I have one in bolt and you are right, it is an awesome choice. However, I ended up just going the Grendel route, for various reasons:

(1) cheaper; as I would have had to invest in AR-10 stuff - I was able to use a bunch of AR-15 parts I already owned for the Grendel. All I really bought was a Satern barrel and bolt in Grendel.
(2) lighter; my 18" Grendel is going to weigh very similar to an AR-15 in 5.56; AR-10 is heavier platform.
(3) relative performance; Grendel is a huge jump up from 5.56mm, however the jump between a Grendel and a 6.5x47L isn't as big - you are really just talking about improved MV. The gas 6.5x47L will still have all the inaccuracies of gas and bump in velocity (maybe 200fps for similar length barrel) just isn't worth all the bigger $ and weight investment to me.

A 24" Grendel will get a 123grain 6.5mm going at 2600. A 6.5x47L of similar barrel is maybe 2800fps? Maybe I'm low on that velocity estimate...

These is just what I was thinking. Your project sounds like one heck of an idea if you aren't invested heavy in AR-15 parts.

 

[bustin]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

You can only seat the X47 out to around 2.7 and still keep some bullet in the case.

On the Lapua brass they have small primers and flash holes so you need to use magnum primers with a case that has over 40gr capacity, some have had better results by drilling the flash hole out about .005"

The X47s have a very long leade/freebore to align the bullet in the bore so they can be more accurate than the 260s if you can get consistent ignition. N550, RE17, 4350 work

A 6.5x47 will push a 123 over 2900 easy, about 350-400fps faster than a Grendel with the same barrel length. I have run a 123 amax as high as 3100 out of a 26" AICS bolt gun.

 

[kLewis]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

Which of these two is more affected by barrel length, and at what length does it become an issue? Thinking between 16", 18", 20", and 22"?

 

[jbailey]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

Hey, I had one more idea for the OP:

6.5 Creedmore.

Reason I say that is because Noveske makes barrels and I know they have build uppers in 6.5 Creedmore:

http://noveskerifleworks.com/cgi-bin/imc...ce=&status=

If you have the AR-10 parts, $600 and you are done. Plus if you run into problems, just give the guys at Noveske a call and they will square you away.

 

[fastford]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

260 or the creedmoor, I have both in the AR platform

 

[SFree]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

6.5 Creedmoor x2. That's why it was developed, to performe in magazine fed rifles, gas or bolt.

 

[Casey Simpson]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

Its a toss up. My experience is with x47 in bolt and gas. 8208xbr, Varget, and RL17 and 123's up to 141's. You will need a better bolt than offered by most makers. The firing pin hole is too large allowing excessive primer extrusion. A hide member said Armalite's is just right. DPMS is not. Get a good builder like Scott Madesha or Sabreco. You want someone's name and reputation at stake. Unless you must have 6.5, consider 6m/m, i.e.; XC, 243Win, 6x47L but a small chassis AR is easier to run, i.e.; 6BRX, RAT, Turbo, etc.
My RAT hammers a hole. My x47 will not, but close.

At 500 yards in the wind, heat, snow, mirage, discerning 260, Cred, x47 will be impossible.

 

[Mohawk3a]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

+1 for 6.5 creedmoor. Cheaper factory ammunition with more variation. I picked up one of the last 6.5 creedmoor uppers noveske had, for my dad. I think your going to see a lot more 6.5 cm ammunition in the future as well.

 

[JL]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

Bustin,
Got some experience with small primers and large charges. Been shooting Lapua Palma over year now. According to my experiences, Normal Federal primer is stronger than CCI magnum- only SR magnum primer available here. CCI might still be able to stand more pressure, I dont know about that.

Casey, thanks for firing pin hole info. I happen to have Armalite BCG in my rifle

About pressures and MV:s- I know about 47Lapua velocity's -but not with shorter 22" barrels. Friend got a RPA Rangemaster at 6.5x47. Hes using 140gr VLD and VihtaVuori N500 -series high energy powder. MV:s 2970fps! Load is hot, but not in a limit. Barrel 25".

Creedmoor guys- thanks...but...as I said, I have narrowed down my options already, and I have a good reason for it.
Its 260 or 47Lapua.

 

[bustin]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

41gr N540 =3057 fps from a 22" AR12
42gr N550 =2987 fps
Both with CCI450 primers.
I have a 20" too but haven't shot it much yet.

KLewis,
The larger capacity of the 260 will need heavier loads to obtain the same vel, also slightly slower powders so it will lose a few more fps/in of barrel. If both cartridges are run at the same pressure they will produce close to the same vel.
IMO the 260 may produce more vel with heavier bullets in long barrels, more slow powder in a long tube. 22" is the longest I will use in a AR also mainly my BRX, 30-50fps doesn't mean much to me.

 

[JL]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

Those loads were with 123gr AMAX?

 

[bustin]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

They were, they're just cheap to work up loads close then I swap over to the SMK or Scenar

 

[RobertB]

Re: AR with 22" barrel- 6,5x47Lapua or 260Rem?

I have and like both rounds. In an AR I think I would go with the .260 though. The .260 handles the 142 a little better and the 123 shoots fine in the x47. That is the bullets I shoot in mine and they seem to be working out pretty good. I think that I would want to be able to shoot cheaper brass if needed for an automatic weapon. The win 7-08 is much cheaper than the lapua brass and shoots just fine with me. I have gotten very similar accuracy with both brass's. If the gun is harder on your brass then being able to run cheaper brass would be a plus. And keeping everything as close to the .308 platform seems like a better thing. I know alot of you guys have the wildcat rounds in AR's and they do fine. I would LOVE to have one but for my budget and expectations would make me lean to the .260 OR .243. Thats just my rattle brain thoughts.