Bigdad

I made an error in my post regarding the Larue trigger. I measured it again last night and the 1st stage does move my scale and measures 1.75 lbs, not zero per my previous post. The 2nd stage breaks at 4.1 lbs. My son just put a Larue trigger on his rifle, it breaks at 3.5 lbs, I'm jealous ?.

Pics

Here's the only pick of the gun/scope I have, it includes a monster pig my son shot at night with it. I'll take a better pic of the gun when I get home tonight.

I thought I would provide an update on my quest to improve my cheapo 308 AR, it may be helpful to others. This is my first real experience with AR type rifles although I did have a pre-band AR15 H-BAR back in the early 80’s that I never really cared for. A couple of months ago I bought a new FEDARM FR-10 308 off of Gunbroker for $455, $501 with shipping and FFL fee. I bought it with the intention of setting it up for night hunting pigs in East TX. I didn't expect it to be very accurate and was pleasantly surprised when I ran various factory loads through it and accuracy ranged from 1.25” to 1.75” inches at 100 yards. Recoil was stout and the ejected brass was really beat up and the gun seemed over gassed. Based on feedback from the helpful experts on this forum, namely 98ZRV, I replaced the buffer with a KAK Heavy Buffer and spring with a Sprinco Orange spring, that really helped with recoil and the brass is no longer damaged. Ejection went from 10-12 ft at 1:00 to 6 ft at 2:00. I did not install an adjustable gas block, I may do that in the future. Next, I replaced the factory trigger group with a Larue MBT-2S, again based on feedback from this excellent forum. They advertise 2.5 lb first stage and 2 lb 2nd stage. I measured the pull and the first stage is really light, wouldn’t move my trigger gauge and 2nd stage released consistently at 4.1 lbs. Not as light as I’m use to in my bolt guns but acceptable for a hunting rifle. Next, I started load development, after trying several bullets using Varget powder, I settled on a load using Nosler 165gr BTs that would shoot 5 shot groups pretty well. 4 of the 5 shots would be under an inch but inevitably one of the 5 would open the group to 1.5” or so. See the first photo below. Next, I decided to lap the receiver face and bed the barrel. I bought a Wheeler lapping tool and lapped the receiver face. I turned the first couple of rotations of the tool by hand to see if the face was true or not. It was true but for good measure I did lap it some. I probably removed less than .0015 of material from the face. When I replaced the barrel, I glued it in (bedded) using Loctite 620. I had to torque the barrel to 80 ft lbs to get the handguard rail to line up with the receiver rail. That concerned me a little. I went to the range yesterday and no longer get fliers and groups are now in the .8 MOA range. See the 2nd and 3rd photos below. I’ll probably continue load development as that’s what I like to do. I don’t know if I can make it any better though. I bought a SIghtmark Photo RT IR night vision scope that works pretty well at night. I use QD rings so I can swap scopes as the Photon sucks for target work and daytime hunting. I’ll take 2 scopes hunting, one for daytime and I’ll switch to the Photon at night. The QD rings work well and I confirmed they hold zero after removing and replacing several times. My son liked my setup so much that he bought the same thing. Now to get started on his.

Thanks again. Very helpful group here on 308AR.com!!

I used a crow foot 90 degrees from the torque wrench. Its my understanding that does not increase the actual torque applied, correct?

The hand guard on my rifle is similar to the one depicted in Survivalshop's post except it take a crow foot wrench. It came with one shim installed between the nut and the extension. I removed the shim and applied 80 lbs of torque to the nut and was able to get the picatinny rails to line up with out any shims.

Thanks again Mr Kiwi.

Thanks for the feedback everyone. Here's another question. I need to to shim the the barrel nut to get my hand guard picatinny rail to align with the receiver rail. I ordered a shim kit from Bison Armory and their installation video shows that the shims should be cut and installed between the barrel extension and the receiver face. Why can't I just not cut them and install them between the barrel nut and extension?

I used a Wheeler lapping tool and 220 grit lapping compound. It didn't require removing much material to true it up. Actually it probably didn't need truing at all. Next I plan to bed the extension to the receiver as the barrel does wobble a bit.

I just lapped the receiver face on my 308 AR. When researching this process several people said not to remove too much material from the receiver or you could cause a head space problem. This confuses me because I thought the head space on an AR is determined by the distance from the bolt face to chamber shoulder. Since the bolt engages the barrel extension not the receiver like a bolt action does I don't understand how removing material from the receiver face can effect head space. Please school me on this issue.

I'm looking for a soft-case that will fit my 308AR. Its 35" oal with the stock collapsed. I currently have a rather large optic (5-20X44mm) but will be installing a larger Sightmark Photon 4.5-9X42mm Nighvision scope. Not looking for a hard case and don't want to spend over $75. Any recommendations?

Thanks for the help

Update - we did a little shooting today after installing the new Sprinco orange spring and the KAK 5.3 oz. buffer. It seems to have helped some. The brass is ejecting 6 ft to the 2 o'clock position instead of 8-10 feet to 1 o'clock. The brass was in good shape and none of the necks were caved like they were before. If it means anything we were shooting Rem 150 gr core-lokt ammo. Question - should I leave it alone or is the next step to install an adjustable gas block? How important is it for the brass to eject at 3 or 4 o'clock?

Hodgdon Load data lists CFE 223 as giving the highest velocity for 165-175 gr bullets in the 308 Win. I bought some CFE 223 to use in my 223 and 308 Win bolt actions. Neither liked it very well, pressure spiked before I could reach the velocity Hodgdon claims and accuracy wasn't as good as Varget. Does anyone have any experience with this power in their 308 AR? Any recommendations on loads? Does it reduce copper fouling as claimed?

I'm new to AR type rifles but have been an avid hunter, shooter and hand loader for almost 40 years. I mainly shoot bolt action rifles and fallen in love with Savages. I like to tinker and swap barrels on my Savages. I also like long range shooting. I recently purchased an inexpensive FEDARM FR-10 308 AR off of Gunbroker.com to hunt pigs with. I ultimately plan to put a night-vision site on it and may add a suppressor at some point. The gun functions well and is fairly accurate. Most of the loads I've tried have grouped in the 1.5 MOA range or better. I haven't been able to consistently break the 1 MOA barrier yet but I think with more load development I'll get there. ARs seem to be a tinker's dream or nightmare depending on your point of view. I want to keep this thing inexpensive but that is proving to be difficult. I've already received a great deal of excellent advice on this forum and I've ordered a LaRue 2-stage trigger, recoil pad, heavy buffer and buffer spring. It probably won't bee too long before I replace the barrel. I hope I don't ask you guys too many stupid questions.

I'll give the tape a try until my spring/buffer arrive, then try it with out the tape and see what happens. Thanks

Well I just purchased the sprinco orange spring and the KAK 5.3 oz. buffer. I went to the range yesterday and necks on several of my ejected brass were caved in. Will the buffer and spring help prevent this?

Many thanks for keeping me straight with all this 98Z5V.

My current buffer weighs 3.71 oz. Is this the one I should get? https://dsgarms.com/dsg-4201-0030. Unfortunately its out of stock. I can just go with the DSG Arms H3 Carbine buffer, correct? Thanks for the excellent advise!

It was a beautiful day in East TX but no deer taken. Saw some doe's, a pig and a spike. Let them walk.

Upon firing, the brass is ejecting 8-10 ft to 1 o'clock with hand loads and factory loads. Its my understanding that 1 o'clock ejecting is a sign of too light a buffer or over-gassing. I thought I would try increasing buffer weight and replacing the spring first then install an adjustable gas block if necessary. Is this the correct approach?

Sorry for the late response, I was in the deer stand all day yesterday. Current buffer is 2.5" and holds 2 weights Its a carbine or mid length system, 16" barrel, the length from face of receiver to rear of gas block is 9.5". Internal length of the buffer/spring tube is 7" Spring is 11 1/8" long Any advice?

Awesome, thanks!

I found Tungsten Recoil Buffer Weights - 1.5 oz each 3-Pack. Can these be added to my existing buffer?