6.5CM or .260 Rem for AR-10 pattern precision rifle??

ReaperDriver

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HI all, I'm in the process of deciding whether to build or buy an AR-10 pattern precision rifle in either .260 Rem or 6.5 Creedmore. Primary use will be long range steel and tactical precision rifle matches. There are some "gas gun only" tac matches I would like to start getting into. This will be a no holds barred build or buy. My main dilema at the moment is which caliber. In terms of accuracy and performance, I think both calibers are pretty much identical. So to me it comes down to function and reliability in the semi-auto platform.

So here are my current thoughts: I already have an AI AT in .260 Rem that is a tack driver and so therefore have all the dies and components ready to go and I know the round well. However, I've heard anecdotal stories that the .260 doesn't feed or function as reliably in a semi-auto as the 6.5 CM due to it's slightly longer case. I'm not sure if there is any truth to that or not though. I did see one very respected local match shooter a while back with a .260 AR-10 that jammed about every 4th round. But of course that could have been just that gun.

OTOH, the 6.5Cm seems to be the tac match standard and getting a new set of dies isn't a big deal. And I have access to a fair amount of 1x fired brass to get me started. I think there is a lot of data out there on 6.5CM and semi-autos as well compared to the .260.

So if you had to choose one or the other caliber for the uses stated above, which would it be and why? TIA.
 

aslrookie

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I had a 260 AR10. It was a pretty sweet rig. If you’re chasing the most flexibility for reloading max performance, I’d go with 6.5cm. Otherwise, the 260 worked for me awesomely. I wasn’t trying to seat bullets at max length or chase max velocity either.

I can see why people gravitate towards 6.5cm for a gas gun, but if you’re already invested in 260rem reloading, then I don’t see an issue. The other nice thing about 260 is I would buy Winchester 308 new brass and just run it through the 260 FL die to make 260 brass.

Being that components are not the easiest to come by right now, you at least have that flexibility to easily convert 308 brass if needed.

As for feeding, I didn’t have any feeding issues even on those stages where you can get unlimited points based off how many hits you can get in 1min or whatever. I did have extraction problems due to a burr inside my JP LMOS carrier that they replaced, but other than that no issues.
 

lash

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I wouldn’t try to convince you one way or another, as I’ve only limited experience and exposure to either. A good friend and shooting buddy has a DPMS in .260 and has a load that works in both the AR and his bolt really well. Zero feeding or jamming issues with his. I also know a good PRs competitor that spent his first two years competing exclusively with a DPMS in 6.5 Creedmoor with no issues.

It may be that the DPMS platform is typically over-gassed, which can help eliminate some feed and cycling issues.
 

viking78

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260rem is so ease to realod.
And you can make brass for it of 243win, 7mm08 and the most uded, 308win.
I run 260rem bolt action guns, i have 6.5 cm too, but i love 260rem.
I think it is better than 6.5cm.
 

lash

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Oh, I won’t deny at all that I am a huge .260 die hard, but the OP asked which one will run better in an AR. As such, I was trying to be neutral. My .260s are both in bolt guns.

3D9EA2F2-F8A7-4631-A83A-DD4573BC2D42.jpeg
 

lash

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And I should mention that the key to loading for your AR for field match use is full length resizing.
 

bigbuckslayer3

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My Gap 260 is very accurate and has ran flawlessly. You would definitely want to reload to get the most out of either.
 

ReaperDriver

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Thanks guys, that is really great info. I exclusively reload for all my precision rifles, so it sounds like staying with .260 is the way to go. I really like the caliber and I hadn't thought about the availability of brass being easier to make from other rounds. I have a TON of .308 brass and I have already resized some Lapua .243 to .260 and it shoots great. I shoot with a buddy that has two bolt guns in 6.5CM and I can pretty easily get 100fps faster than his max load 6.5. At 1000-1500 yds, I can see a difference.

Thanks again.
 

ReaperDriver

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Hey, quick follow up question I forgot to ask. I shoot Berger 140 Hybrids in my .260 AI at 2.950 OAL. Obviously that's too long for mag length in a .308 PMAG for a gas gun. Are you guys able to shoot the Berger hybrids at Mag length and still have good accuracy? It seems like they would be really seated deep. Or ar you limited to lighter bullets that are shorter? How about for the 6.5CM guys? What bullets can you shoot in the gas gun. Thanks.
 

aslrookie

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Hey, quick follow up question I forgot to ask. I shoot Berger 140 Hybrids in my .260 AI at 2.950 OAL. Obviously that's too long for mag length in a .308 PMAG for a gas gun. Are you guys able to shoot the Berger hybrids at Mag length and still have good accuracy? It seems like they would be really seated deep. Or ar you limited to lighter bullets that are shorter? How about for the 6.5CM guys? What bullets can you shoot in the gas gun. Thanks.
If memory serves me right, I was using 120-130gr SMK
 

lash

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Hey, quick follow up question I forgot to ask. I shoot Berger 140 Hybrids in my .260 AI at 2.950 OAL. Obviously that's too long for mag length in a .308 PMAG for a gas gun. Are you guys able to shoot the Berger hybrids at Mag length and still have good accuracy? It seems like they would be really seated deep. Or ar you limited to lighter bullets that are shorter? How about for the 6.5CM guys? What bullets can you shoot in the gas gun. Thanks.
I personally haven’t used the Berger Hybrids, but have heard that they handle large jumps pretty well. I do know that the 136 Lapua Ls are very tolerant and handle the shorter OALS very well.