AR-10 AR308 Platform Cartridge Options

[BigNate]

WW AZS Do?

I've started shooting some Accurized AR type stuff and am interested in building an AR-10 / AR308 type rifle for that sort of shooting. I'm looking for the following (in order of priority)...

1) Ability to use "standard" AR-10 / AR308 magazines and lowers (not interested in buying a Falkor or NEMO or... XXXX in .300 WMG etc.) Need to keep C.O.A.L. at under about 2.820 (seems some magazines may allow up to 2.870, but...)
2) Flat, fast bullet - wanting to grow my ability to put rounds on steel at 1000+ yards
3) Availability of cases and projectiles for reloading.
4) Availability of parts from multiple sources
5) Magazine Capacity - I'll probably avoid things with a really large case diameter (e.g. .300 WSM) due to the reduced magazine capacity. This is low on the list - I may be talked off of this one - but right now I'd like to maintain a 20 round single mag capacity without using some Frankenstein magazine that makes shooting prone impossible.

I'm not worried about working through tuning the gun / gassing issues / etc. (ok - I hear the 'Yoda' out there saying "you should be... you should be..." - yes - I'm worried about it - but I'll be working through that). Right now I'm considering:

.243 Win
.260 Rem
6.5 Creedmoor

Do you have others that I should consider? TIA

 

[Kinked_Chrome]

6mm creedmoor should be on that list if your considering 243 win.

Most of the new novel cartridges have shorter cases relative to the COAL that will make it easier to meet mag length if you choose a long high bc bullet.

On the flat and fast point, if you are after a fast light bullet, keep in mind that most PRS style matches want you under 3200fps, but if you choose a heavy for caliber bullet that probably wont be an issue.

 

[Suck My Glock]

Agreed. 6mm Creedmore is cool and all, but the heavier 6.5s will buck the wind better, while still recoiling less than a .308Win.

I have a 6.5Creedmore AR10 build in my future.

 

[iammaxwell]

I've stuck with my boring ol LR308. Will do everything on your list except be the "fastest and flattest". Plus, I have commonality of caliber with other rifles. Of what you listed, I'd go 6.5 creed. If you could find a 7mm-08, might be worth considering. Great round, especially if you're going to hand load.

 

[TheJediknight]

I've stuck with my boring ol LR308. Will do everything on your list except be the "fastest and flattest". Plus, I have commonality of caliber with other rifles. Of what you listed, I'd go 6.5 creed. If you could find a 7mm-08, might be worth considering. Great round, especially if you're going to hand load.

When I was researching mid to long range, I liked the 7mm ballistics.

I stayed with .308Win and 300WM.

 

[XJThrottle]

300WM fits in a standard 308/AR10 lower?

 

[TheJediknight]

Fits in a Remington 700 Sendero bolt action rifle.

 

[XJThrottle]

Fits in a Remington 700 Sendero bolt action rifle.

I have a stainless 700 SPS in 300WM, so I already have ammo. I've been thinking about doing an AR10, but was on the fence about caliber. If 300WM was straight forward, I'd go that route.

 

[BigNate]

I've stuck with my boring ol LR308. Will do everything on your list except be the "fastest and flattest". Plus, I have commonality of caliber with other rifles. Of what you listed, I'd go 6.5 creed. If you could find a 7mm-08, might be worth considering. Great round, especially if you're going to hand load.

I have an Armalite AR-10(T) that I really like - but I'm looking to build another in a faster / flatter caliber.

I'll add the 7MM-08 to my list to review / consider. Thanks!

 

[TheJediknight]

I would like a one chambered in 308 or 300.

 

[BigNate]

300WM fits in a standard 308/AR10 lower?

No - it does not. There are a few companies that are building "AR" looking rifles in .300WM but they really are not close to the "standard" AR-10 (despite the fact that there is no real standard for AR-10 / 308AR pattern rifles) due to the longer cartridge.

I understand that you CAN get bolt and barrel for .300WSM .300RSAUM and some of the other short mags - and that these can be loaded to a COAL that works in the "standard" AR-10 platform guns - but that the case is so much fatter than the 7.62X51 that the magazines were made for that you end up with an almost single stack magazine situation which I want to avoid.

 

[BigNate]

Fits in a Remington 700 Sendero bolt action rifle.

I have a stainless 700 SPS in 300WM, so I already have ammo. I've been thinking about doing an AR10, but was on the fence about caliber. If 300WM was straight forward, I'd go that route.

.300WM AR can be very "straightforward" - you buy a one-off gun... https://falkordefense.com/petra/ . Lots of coin - and not something that will be easy to tweak down-stream if you want to modify it. If I had a spare $9K - $10K laying around (don't forget glass) with nothing better to do - I might buy one... Kids in college have first dibs on that money... ;-)

Unfortunately - it is not a cartridge that works in any of the "standard" AR pattern buildable guns.

 

[TheJediknight]

Fits in a Remington 700 Sendero bolt action rifle.

I have a stainless 700 SPS in 300WM, so I already have ammo. I've been thinking about doing an AR10, but was on the fence about caliber. If 300WM was straight forward, I'd go that route.

.300WM AR can be very "straightforward" - you buy a one-off gun... https://falkordefense.com/petra/ . Lots of coin - and not something that will be easy to tweak down-stream if you want to modify it. If I had a spare $9K - $10K laying around (don't forget glass) with nothing better to do - I might buy one... Kids in college have first dibs on that money... ;-)

Unfortunately - it is not a cartridge that works in any of the "standard" AR pattern buildable guns.

you are right , when i went to look , i'll be darned if they weren't 300AAC.

Found this....

https://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_ID=2032

 

[BigNate]

I have a stainless 700 SPS in 300WM, so I already have ammo. I've been thinking about doing an AR10, but was on the fence about caliber. If 300WM was straight forward, I'd go that route.

.300WM AR can be very "straightforward" - you buy a one-off gun... https://falkordefense.com/petra/ . Lots of coin - and not something that will be easy to tweak down-stream if you want to modify it. If I had a spare $9K - $10K laying around (don't forget glass) with nothing better to do - I might buy one... Kids in college have first dibs on that money... ;-)

Unfortunately - it is not a cartridge that works in any of the "standard" AR pattern buildable guns.

you are right , when i went to look , i'll be darned if they weren't 300AAC.

Found this....

https://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_ID=2032

Neeato... I shudder to think of the cost of a day out shooting with the kids... and hearing them mag-dump rounds that cost $8.00 each. :shock:

I guess the guy who buys a $6000 semi-auto rifle is OK paying between $4.00 - $8.00 per round to feed it...

 

[XJThrottle]

.300WM AR can be very "straightforward" - you buy a one-off gun... https://falkordefense.com/petra/ . Lots of coin - and not something that will be easy to tweak down-stream if you want to modify it. If I had a spare $9K - $10K laying around (don't forget glass) with nothing better to do - I might buy one... Kids in college have first dibs on that money... ;-)

Unfortunately - it is not a cartridge that works in any of the "standard" AR pattern buildable guns.

you are right , when i went to look , i'll be darned if they weren't 300AAC.

Found this....

https://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_ID=2032

Neeato... I shudder to think of the cost of a day out shooting with the kids... and hearing them mag-dump rounds that cost $8.00 each. :shock:

I guess the guy who buys a $6000 semi-auto rifle is OK paying between $4.00 - $8.00 per round to feed it...

Not really any different that mag dumping a 300BO loaded with subs.

 

[Old Jeff H]

I wanted to think on this for a couple of days, and let people with more knowledge than me reply before I did.

IMHO, if you want an AR style rifle, and you want parts/ammo/components that are readily available and relatively cheap, I'd just stick with 308. Plus it has compatibility with your M1A.

However if you want to get serious about shooting 1,000 yards, and doing so competitively, I'd be looking at a 6 or 6.5 bolt gun.

 

[BigNate]

I wanted to think on this for a couple of days, and let people with more knowledge than me reply before I did.

IMHO, if you want an AR style rifle, and you want parts/ammo/components that are readily available and relatively cheap, I'd just stick with 308. Plus it has compatibility with your M1A.

However if you want to get serious about shooting 1,000 yards, and doing so competitively, I'd be looking at a 6 or 6.5 bolt gun.

Thanks Jeff... I'm looking at this specifically for Accurized AR match stuff. I've got an AR-10(T) and a build based on a PSA 223 Wylde upper - both of which I picked up from car buddies... Right now I'm shooting the .223 for economic reasons (cost of match grade rounds) but my OCDishness is kicking in and I'm thinking about what I can build that will give me faster, flatter with longer legs... I picked up a bare Aero M5 lower a while ago that sits in the safe and every time I see it I feel guilty that it does not have parts added so that it is more than a paper-weight... LOL.

I've also been toying with putting together a long range bolt gun - but that will probably be something in a cartridge that can stretch even further. No clue yet what that will be - but guessing something in the range of cartridges between .300 WM and .338 Lapua - thinking .300 PRC, .300 Norma, etc. but no clue where that will actually land other than that I know that I don't know. That will be a research project for another month (or year)...

 

[BigNate]

If you're taking a .300 WM to let kids mag dump, well that's on you. I only take my Nemo Omen Recon out to shoot flat and hit hard at long range with my precision shooter friends.

https://nemoarms.com/product/omen-recon/

One of my friends in the PRC game in VA, absolutely swears by the .260 for it's extra case capacity. He shoots his large frame Larue a lot. The only reason he has sidelined it, because the 6.5 PRC has that case capacity that so often loves but can only do it from one of his AI bolt guns.

I've recently got another form 1 back. I was going to leave it as is as a spare but am now going to turn it into a mini recce using a 12" Faxon 6mm ARC barrel, using a JP Grendel II bolt paired to an NP3 Sionics coated MIcrobest carrier. Not a large frame but something to consider as that round is very flat and even at 300 yards, it's still cooking at over 2,000 FPS even from a small 12 incher.

Thanks - good information. .260 Rem is currently at the top of my list. I've got a local friend that built one and loves it.

 

[Yugmoto1]

I built my AR-10 inn6.5 creedmoor, not because I think it's the best thing ever, but it is fun to shoot and when I built it I bought bulk s&b cheaper than I could find .308. But that was then. But if you're going to compete, and load for it I guess you gotta pick the one that works for you best. I planned to use mine as a hunting rifle when I can, I built it light enough, and the 6.5 is nice enough that my wife likes to shoot it as far as recoil goes. She didn't like the 308. Is .260rem more difficult to use in the AR-10? As far as fit and function? The 6.5 was easy.

 

[Yugmoto1]

.260 is interesting, I think you can get a bit more out of it than the 6.5 maybe. But I'm not at that level. As long as it works and that's what you're after it'd be worth a look.