AR10... 6.5 or .308?

Boman21

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I’ve got an upper and a lower for an AR 10 build. Trying to make a decision on which direction to go, 6.5 Creedmor or .308. Looking for some help from someone that has experience with AR10s that could nudge me one way or the other with their experiences. I want to use it for long range applications. This will be my first build so any advice would be much appreciated!
 

mdvctry

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I have both. Neither are built necessarily for long range precision and locally I can only shoot out to 100yds on public ranges. I use them primarily for hunting deer and hogs. My 6.5 Creedmoor is more accurate, less recoil and a bit lighter. I would suggest getting one lower and two uppers one in each caliber and see which one you prefer over time.
 

Hawkeye Pierce

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When you say long range applications, are you talking about paper or hunting?
If you are talking about hunting within about 600 yards if I am recalling the correct ballistics, the 308 carries more energy. If it's smaller animals, or paper. about an inch at a hundred yards is pretty good for an average semi automatic, or factory ammo if you can get the match grade. it really depends.
 

cohunt

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If you handload, the 308 is better IMHO.
The det mag limits the ability to load much longer than mag length unless you start notching mags. You can also get subsonic 308 if you like .

In 308 you can go from 110gr up to 220gr bullets so you have a larger range to choose from.
 

Boman21

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When you say long range applications, are you talking about paper or hunting?
If you are talking about hunting within about 600 yards if I am recalling the correct ballistics, the 308 carries more energy. If it's smaller animals, or paper. about an inch at a hundred yards is pretty good for an average semi automatic, or factory ammo if you can get the match grade. it really depends.
I would be shooting paper more than anything. I would also be hand loading for as much accuracy as I can get. That being said, I’m not expecting any extreme precision from a semi-auto, but I’d like to be as close to MOA as I could be. And I’d love to run it out to 1000yrds, just not sure how realistic that is
 

xsn10s

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I had an AR10 in 308 back in the 90's. As far as accuracy it's probably a wash. It'll be more dependent on the build quality and barrel. The 6.5 CM has the potential for flatter trajectory depending on the bullets you use. But it you really want to shoot accurately out to 1000 a bolt has a better chance of doing it accurately. And the brass life will be better.
 

762x51

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i dont think you'd go wrong with either. i originally built a LR308 but didnt care for the barrel i used. once i found out about 6.5CM, i changed out the barrel using a ballistic advantage 22" 1:8. it's probably my favorite rifle or at least it is this week. it's heavy though, the barrel is .936 at the block and even thicker between the block and the receiver.

it's less recoil than a 308 but i really didnt think the 308 recoil was that bad either. i use a standard A2 flash hider. i just got an adjustable gas block for it that i need to fine tune and the recoil should be even more manageable. i built it for punching paper and hogs.
 

GrayCreed

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I'm a creedmoor guy but I'm going to say 308, the AR10 isn't really a "long range platform" when compared to some of what you can do with a nice bolt gun. However, inside 600y I think you could do just fine with the 308. I know folks out there are putting 65creed barrels on AR10s and I think it's really cool but that's something that you should do AFTER you've built a 308.
The main two things with the AR10 are magazine limiting length and barrel length. Both of these severely limit the creedmoor in the AR10 platform. Personaly I think a 65creed needs a 22" barrel absolute minimum. At the same time you could do just find with a 308 in the 18-20" variety.

Bottom line I would build you a creedmoor right after you finish your 308!
 

Txhillbilly

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You don't have to limit yourself to the 6.5 CM & 308 Winchester. You can also get barrel's in 243 Winchester, 6mm CM, 260 Remington, 7mm-08, 338 Federal, 358 Winchester, and many more.

I have an LR-260, and love it. The main reason I went with the 260 Remington over the 6.5 Creedmoor in this platform was cheap brass that wouldn't bother me if it was lost in the field while hunting hogs.
If I ever build another upper for a "Target" gun, it'll be in 7mm-08.
 

budlight

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I'm the proud owner of two rifle length +2 inch 24 inch SS fluted Ar-10's in 308. rifle length or even better the longer gas tubes decrease the pressure on the BCG making it much easier to tune even with slower burning powders. I was a military M-14 man. So I always had a love of the 308 and understood it's limitations.

Cheap plentiful brass. I use TNT 125 grain for varmints and an assortment of other for out to 600 yrd paper
 

mongo4567

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I use mine mainly for hunting. I prefer the creedmoor because we have smaller game here in Texas and I use 120-130g loads.

The vast majority of 308 ar10s have a 1:10 twist. With a 10 twist I've had a lot of issues getting exceptional accuracy out of common nato loads or lighter off the shelf hunting or practice ammo (147-150g). I have two rifles that will stack most any 168g loads in one hole, but have trouble getting near 1moa with 150s. This is just my personal experience with lots of powders, bullets, and different factory loadings on two heavy barrel rifles. I even bought a slower twist barrel for an ar10 308 so I can plink with cheaper surplus when I get it swapped.
 

bamban

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For paper punching at 1000 yards, a 20 inch AR308 with 4.5X scope can hang. First 1000 yard match during the 2018 NRA Nationals at Atterbury, my old shooting partner posted 200-15X against the top 1000 yards prone shooters in the country shooting various cartrdges.

Screenshot_20210414-160900_Gallery(1).jpg
 

Hecouldgoalltheway

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For paper punching at 1000 yards, a 20 inch AR308 with 4.5X scope can hang. First 1000 yard match during the 2018 NRA Nationals at Atterbury, my old shooting partner posted 200-15X against the top 1000 yards prone shooters in the country shooting various cartrdges.

View attachment 279566
The guy in 5th place was a friend of mine while I was on active duty. We were in the same platoon together. He had a presidents 100 tab for pistol and spent about 8 years at the AMU.
 

Web1350

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I’ve got an upper and a lower for an AR 10 build. Trying to make a decision on which direction to go, 6.5 Creedmor or .308. Looking for some help from someone that has experience with AR10s that could nudge me one way or the other with their experiences. I want to use it for long range applications. This will be my first build so any advice would be much appreciated!
As others have said, it depends on what your use is. I, personally, like the .308 as it has more power for larger animals and can shoot heavier bullets. Both are very accurate for long range as the .308 was the "go to" caliber for many years in the military. Nothing wrong with the CM but, IMHO, the .308 is better.
 
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