title sums it up
I built an ar-10 in 308 to be my allpurpose rifle, goal was 0 to 1000 yards. the more I read about this newer cartridge the more I think building a second upper is the way to go to push it out to 12 or 1300 yards
ideas advice experiences?
I shoot a 260, which is almost identical ballistically, and love it. The Creedmoor is a better fit for a gas gun though. In all honesty, other than the sheer amount of available ammo, I can’t think of a good reason to take a 308 over the Creedmoor. IIRC match ammo for the Creedmoor can often be cheaper than for 308. I’d do it if I were you.
Well 308 / 7.62 barrel , and this was my first ar10 upper, I wanted standard cal first, I was looking at the exotic large bore calibers that were out there for the next upper but it seems most of those died out rather fast… Sad that 510 whisper looked like a scary monster…
The more I want to get into ultra long range the moor that creed more looks like a great round… But that’s on paper no field use…
Well, a good indicator of long range performance is to look at what the guys in the PRS run. You’ll find both 6 and 6.5 Creed to be extremely common, and for good reason. The better ballistics combined with lower recoil make an effective combo.
I have a good friend that is running that cal on an AR platform. He has a 18 barrel (kreiger) shooting box ammo. He says it hits really well out to about 1150-1200. Mine is on a bolt action, which has a little better max range. All I can day about either gun, is that they are some of the most fun I have had in a while shooting. We have steel setup to 1400 yards and can shoot all day long with no fatigue at all. It’s the best purchase I have made in a long time.
Dang, I love my six and a half C. If I could have only one, my 6.5 C gas gun is it…
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So what did the op do ? I hate threads that have no ending.
user I do agree, the 6.5 out matches the 308 in every way, either gas or bolt.
Lately I’ve been thinking about a 6.5CM sniper/precision rifle for something new. Maybe a semi-auto. BUT when you say all-purpose rifle I just don’t necessarily see the 6.5CM being the best round for “all purpose” shooting.
Right now my all around shooter is a SCAR 17, the .308 round can be bought really cheaply for run and gun on steel out to 200-300 yards. I’ve bought surplus ammo and cheap ammo for plinking and practice, and match ammo for more serious work. And reloading .308 is cheap. With good reloads I’ve seen people shoot 600-800 yards.
I just can’t see running around blasting steel with 6.5CM, but I’m still new to the caliber so maybe cheap CM is available. Practice is the name of the game IMHO, if you use 6.5CM your practice might get too expensive to do frequently. Of course that might not be an issue for you. JMHO
Geez, a couple days ago I bought a bunch of crappy Federal M80 for $10.99 a box and IMI M80 500 rounds for $300, and I’ve been able to buy surplus Radway Green for a lot cheaper than that.
I’ve owned two different .260 Rem AR’s, still have my GAP .260 built on DPMS receivers with a Bartelin barrel. I also have numerous friends with 6.5 Creedmoor AR’s, and have worked on them.
The biggest challenge you will find with any of the 6.5-08 class of cartridges in the AR10/LR-6.5/DIY build is dealing with the primer support, and the gas system, in addition to all the other challenges faced with the large frame AR’s.
For starters, you really do need a smaller firing pin aperture and pin so the bolt face more fully supports the primer, otherwise cratering and piercing are common.
Getting the guns to function smoothly with 139-142gr loads is the biggest challenged. 123gr works a lot better with milder loads. If you read JP’s tech notes on this, you’ll see the same statement.
I personally like the standard Berger 130gr VLD in mine, but I don’t know of anyone else that has been able to get the standard VLD’s to cycle in their guns without hitting the breach of the chamber. The sharp VLD noses are able to ride lower in the notches for the bolt lugs between the barrel extension teeth, and don’t make it into the chamber on most guns. Mine works for some reason.
My gun is a hand-loader’s only set-up. Some people have been able to get their 6.5 CM AR’s to run with factory, after many trips to the range, mods, tweaks, bushed firing pins, adjustable gas blocks, tuned extractors, custom buffers, and recoil spring mods. I’ve bent at least 3 firing pin retaining pins, pierced who knows how many primers now, and have had to redo load development several times with mine.
ELR performance and accuracy are up there though, and I have more retained energy on target than a .30-06 from 275 yds out, trajectory like a top-end 300 Win Mag, with slightly less recoil than a .308 Win.
6.5 Creedmoor prices and support from Hornady have been very good, and Winchester just started making ammo for it. I just wish they would make a gas gun load with the 123gr AMX and 129gr SST. Precision Firearms makes some really nice 123gr 6.5 Creedmoor ammo, and watching it next to .308 at the range through the spotting scope is night and day. 6.5 CM and .260 Rem fly straight to the target with very little vertical, whereas .308 is like a rainbow arc. Especially on a range facing East, right before sunset, when the reflection off the backs of the fully jacket projos makes them look like tracers, you can see exactly what I’m talking about.
Dang. Mine 6.5C gas gun and My buddies work great all through last years precision rifle series with zero issues shooting crap loads of 140 AMAX and 142 Sierra, factory and hand loads. Individually we shot just over 4k in gas guns in 2014. Never heard of issues
With primers or getting them to run.
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We shoot Krieger barrels and DPMS BCG’s …
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What gas system length are you using? Krieger normally uses a .086" port diameter on the 6.5 CM with an ArmaLite RLGS.
I have not seen anyone able to shoot factory loads without cratering at least, especially with the DPMS BCG and its large primer aperture. That’s what I have, and almost every batch of loads I have done has seen some degree of cratering, simply due to the large firing pin aperture.
Are you using adjustable gas and special recoil systems?
24’ with rifle gas. Non adj.
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That’s a hell of a long barrel! 
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I Just Completed assembly of the following:
Mega MKM MATEN Extended Rifle Length Key Mod Set
Geissele Hi-Speed 2 Stage Match Rifle trigger
Rainier Arms Match .308 - 18" SS barrel
Rainier Arms UltraMatch .308 BCG
Syrac Ordnance Gen II adj gas block
Magpul UBR Stock
JP Enterprises AR 10 Silent Captured Spring
Nightforce 3.5-15 x 56 ZeroStop Scope
Bobro 30mm one piece scope mount
Noveske Raptor Ambi Charging Handle
Lantac Dragon Muzzle Brake
ERGO Tactical DLX - Grip
I am waiting on a 22" Rainier Arms UltraMatch barrel in 6.5 Creedmoor with a MEGA Arms MKM upper that I will interchange with the 308 upper. (This will also be topped with a Nightforce ATACR 5-25x56 ZeroStop scope and a Bobro mount). Barrel should be arriving in the next week or so.