You want the 308 version shown here

Heads up, Rainier has DPMS Phosphate 308 bolt/carriers in stock. Get them quick.

I'm getting my shopping list together to build my first AR platform rifle and want to do it in 308. Here's what I've come up with so far and I would like to get some feedback on any parts that wont jive together or if any of you feel there's a better part/value to replace something on my list. Thanks in advance.

ETA:
Upper/Lower/Rail: Mega Monolithic Upper/Lower set ($980 maybe less w/ coupon code) http://www.aimsurplus.com/product.aspx?item=F1MegaMTS4400SRifle&name=Mega+Arms+MA-TEN+.308+Monolithic+Receiver+Set&groupid=11
LPK: (parts needed to complete) from RRA
Trigger: Geissele SSA ($170) http://www.aimsurplus.com/product.aspx?item=XGASSA&name=Geissele+Semi-Automatic+(SSA)&groupid=576
Barrel: Rainier Arms Select 18" ($260) http://www.rainierarms.com/?page=shop/detail&product_id=2689
BCG: DPMS Chrome ($250) http://www.rainierarms.com/?page=shop/detail&product_id=2456
Gas Block system: Rainier Block and tube ($60)
Muzzle Brake: PWS FSC30 ($95) http://www.rainierarms.com/?page=shop/detail&product_id=960
Stock: Command Arms SRS ($350)
Buffer: Slash Heavy Buffer - ($99) http://www.heavybuffers.com/ar10carbine.html
Bipod: Harris BiPod ($100)
Scope: Osprey 10-40x50mm Riflescope ($230)

Total: $2594

Just get a gas block from Rainier Arms and a mid length tube. You also need a muzzle device.... I got the Rainier Arms one - good price and I was already ordering their 18" stainless barrel.

I didnt know Rainer made a 308 muzzle device?

I didn''t see one either...they had one for 6.8 and 5.56 but no 7.62. I saw some pretty good reviews of the PWS one I posted above over at sniperhide and it wasn't too expensive so I'll plan on going with that one.

Yeah I f'd up. I'm building a 300blk pistol at the same time as my MaTen Nib. Glad you guys set me straight. I actually loosely installed the comp on the MaTen without even thinking.

I posted a thread in Rainiers industry section a while back asking them if the one for 300blk\6.8 would work on a 308 since it was threaded the same they said it would go on the barrel but wasnt desigened for it. But they did say they were in the process of developing one for 308, BUT since they dont have one i will also be going with the PWS FSC30 also i havent seen anything but good reviews on it also.

Anyone have any first hand experience with a JP adjustable gas block on a 18" Rainier select barrel? I am making a 3 Gun Mega build......

T

Finally !!! after around 3 months got my upper/lower in.



parts:
krieger m110, chambered threaded and timed. 620$ (bead blasted)
jp enterprises large compensator 100$ (shaved down the diameter to match the barrel) (timed with shims for now)
fulton armory gas block and gas tube 87$ (note: my order did not come with the gas tube pin. had to order from armalite)
armalite ar10 bcg and pri qc brake 337$ (the pri brake was a smaller diameter than my barrel..... derp. was not thinking.)
bullet button 19$
dpms upper receiver vise block 62$
quick detach push button sling swivel 10$
magpul rail covers 30$ (not pictured)
timney trigger skeleton 250$
lower parts sourced from rock river 30$
magpul ubr stock. 240$ (gunshow)
2 magpul 20rd pinned 10's 40$ (gunshow)
magpul maid grip 25$
heavy buffers ar10 buffer and modified spring 110$
MA-TEN upper/lower monolithic 1000$
Leopold mark 4 4.5*50mm lr/t m1 tmr 1200$
larue tactical spr 1.5 mount 120$ (purchased from a friend)
atlas bipod bt-10 210$ (still back ordered and yes midway does have them in stock at the moment.)
––––––-
4480$ plus tax and shipping and dros!!! expensive but so far worth it.
still need to buy some iron sights.

next to my 15


just put it all together. anxiously awaiting Sunday to go shootin!

Update. Best group so far. sub moa every group but heres my best.

found answer, please delete

Finally got to shoot mine today. The gun is capable of much better, it seems that I am not however. Guess I need to shoot more.

100y shooting 168 FGMM. Prone from a bipod.

Looking at getting the LaRue A-Peg grip. Should I get the AR15 or the AR308 version for my MaTen?

Could be wrong, but I think you want the AR15 version for the MATEN as it was specifically designed with AR15 parts in mind. I mean if my MIAD fits perfectly, then an AR15 APEG will. I think some 308s will have a gap at the rear/top of the grip using an AR15 grip.

I got the 308 APEG for my MATEN and it had a decent gap at the back had to do some dremeling, ended up just putting it on my AR instead after using teh bremel on it just wouldnt fit right going to get a MIAD for the MATEN.

Thanks to everyone for all of the information and tips, very helpful thus far but I am having gas tube insertion issues. I purchased an AR-10 gas tube from Armalite and neither end will go through the upper's hole. I already have the barrel seated (incredible how tight the fit is) so drilling it is going to require a long bit that I do not have. I'd prefer not to drill. Do I need to purchase a special tube or what?? Thanks in advance.

Pictures? Do not drill anything. Gas tubes should fit fine, if they don't you're doing something wrong. Need more info.

I can take some later but the problem is pretty straight forward. The delta ring and barrel nut all line up fine, I can get the tube past them and up to the hole at the front of the upper receiver but it will not go through from either end. I've put several AR-15's together and it is always pretty loose there.

I am having trouble getting my gas tube in, I can take my block off no problem. I have a PRI adjustable, and the gas tube I got from Midway. I can not get the thing in there. I am thinking about doing the freeze the tube and heat up the gas block, see if that does the trick. If not I will have to look for a new gas tube. Which is pretty hard to find right now.

This is my first AR build and I wanted to thank all you guys for motivating me to get the MEGA. Great rifle and great price!
I built this to be a Heavy Metal 3 Gun rifle. The SJC makes a HUGE different in recoil!

Parts:

MEGA matched upper/lower
Rainier SS 18" Ultra Match barrel
14" Apex rail
Armalite BCG
JP SS Adjustable Gas Block
SJC Comp
DPMS 308 rifle buffer
DPMS 308 recoil spring
GI A1 buttstock



7 rounds of 147gr WIN FMJBT reloads with 42.5gr TAC at 100yrds in 1.142"


5 rounds of 168 Hornady match reloads with 43.5gr Varget at 100yrds. 5 into 1.112" and 4 into .645"

I spoke with Jason at Mega and he states he has not heard of the issue with a gas tube not fitting but to try tapping it in. I'd prefer a non-interference fit but after the head of it goes past it will be a smaller diameter. He also states not to put the upper in an oven but to use a heat gun on the barrel nut thread area. Armalite barrel extensions are apparently the hardest to fit but even a hair dryer worked for him. I had the upper in a 250° oven for 20 minutes and barely got the barrel in. A lot of tapping with a rubber mallet. Scary.

Edit: It went in fine today for some reason. I doubt it had anything to do with the upper being hot or the barrel being cold yesterday but after a little rotation (no tapping) the gas tube went in with minimal force. Also installed the SSA-E trigger into the lower. Should be functional by the weekend.

I confirmed that a standard handguard set will work with the Mega upper in case it needs to be added to the FAQ. Using the Armalite delta ring set, handguards and gas block with front handguard cap mating a DPMS barrel nut will adapt it all to the Mega billet upper. Most will ask why use this low end setup on a high end upper and I give the same reason for owning lots of guns, why not. That and this gives you the chance to shoot while you wait for LaRue to make a rail setup that WILL fit.

Parts:
Mega Ma-Ten Upper
Armalite 20" NM SS Barrel
Armalite Delta Ring/Spring/Slip Ring
DPMS Barrel Nut
Armalite Rifle Length Handguards
Armalite Handguard Cap
Armalite Gas Block and Gas Tube

Just for your information the new grip from Larue ( Larue Tactical A-PEG) will not fit on the Mega MA-10 Lower. Build in progress....pictures to come

Will not fit