LR308 build

[Rob0115 1,107]

I started to collect the parts to do an AR in .308. I have a Scar 17 but not an AR in this caliber. The factory rifles are pretty expensive so I'm look informs good shooter on the cheap side.

 

I have acquired the upper (A3 flat top with forward assist, charging handle and dust cover) and the matching lower and LPK. I went with all DPMS as the pattern is the most flexible.

 

I am looking at a 16" rainier arms polygonal rifled barrel that I want to cut to 14.5 and I'll permanently attach a comp on it. For a comp I'm leaving towards a PWS FSC30. I'm thinking DD lite rail in 12" and an RRA operator A2 fixed stock or a magpul fixed stock if they have it in .308.

 

I'll post up pics as I move it forward.

[vladtepes 1,060]

I have a 16in barrel and wish I had a longer one in 308.. 

[pbkid6974 1]

a 14.5 inch barrel is pretty much defeating the purpose of building a .308 gun. sure it will be handier but the trade off of velocity in my opinion is not worth it. if you want .30 caliber in an ar platform with a 14.5 inch barrel look into a .300 blackout. i personally wouldn't go shorter than 16 but if i was building one right now i would look for and 18 or 20 in barrel. let that .308 reach out and touch something. i realize that we all want, what we want. if that's what you want then go for it. just some food for thought.

[vladtepes 1,060]

my understanding is that 18 is ideal.. 

[RUTGERS95 890]

I believe 18 is where you begin to get the benefit of the full powder burn in the 308s but could be wrong. 

[Rob0115 1,107]

I have a 300 blackout. I posted so I could get opinions. Perhaps 18 is the way to go?

 

Do you guys think a brake is necessary on 18"? If so I was thinking pws fsc30. I have it on my scar and like it. Rainier guarantees sub Moa on their barrel at 100 yards.

[JimmyAGR 54]

When I was buying my Larue OBR years ago I was pondering the same thing. I called and spoke to their tech department and told them that I wanted to use this in a long range shooting course out to 1000+ yards. He said they would all get me there and that the 16 inch was holding better then 3/4 MOA at that distance. The velocity difference between that gun and my 24 inch bolt is less then 200 fps. I have the Surefire break on mine in the hopes of one day living in a free state so I can get a can.

[vladtepes 1,060]

When I was buying my Larue OBR years ago I was pondering the same thing. I called and spoke to their tech department and told them that I wanted to use this in a long range shooting course out to 1000+ yards. He said they would all get me there and that the 16 inch was holding better then 3/4 MOA at that distance. The velocity difference between that gun and my 24 inch bolt is less then 200 fps. I have the Surefire break on mine in the hopes of one day living in a free state so I can get a can.

 

 

what the hell are you holding at on a 16in gun to make hits at 1000.. like how does that even work?

[Sharrie*1 1]

I too am building a LR308. Just purchased a Rainier UltraMatch .308 in 18". Looks real nice, but have not assembled it as of yet so I am not sure how good it is...have not read anything bad though.

[pbkid6974 1]

what the hell are you holding at on a 16in gun to make hits at 1000.. like how does that even work?

 the bullet drop is right around 20 feet at that range. even more with the 16 in. barrel. so that is one hell of a shot. but it can be made

[JimmyAGR 54]

what the hell are you holding at on a 16in gun to make hits at 1000.. like how does that even work?

It is roughly at 45 MOA drop at that point and the bullet is traveling just under 1200 FPS. The bolt gun is dropping about 36 MOA and traveling about 80 FPS faster. The bolt has over 600 lbs. of energy and the gasser has over 500 lbs. of energy. Might be more of a rainbow, but still will hit hard. 

 

Edit that is with 175 Sierra MK handloads. 

[Rob0115 1,107]

Ok, here's the complete list of what I have to assemble my LR308:

DPMS lower

DPMS upper with charging handle

DPMS LPK w/two stage trigger

DPMS BCG.

RRA mil spec buffer tube

DPMS buffer

DPMS buffer spring

Seekins precision adjustable gas block

Rainier Arms match select barrel 18"

Rainier arms gas tube

Primary Weapons Systems Precision Rifle Compensator

Daniel Defense 12.0 light rail.

 

I'm still hung up on which stock to get. I'd really like a PRS but have mixed feelings about NJ issues related to the stock as out forward in another post.

[Rob0115 1,107]

Upper with forward assist, dust cover, BCG and charging handle assembled.  Lower completed minus buffer spring and detent (pictured).

 

[Bully 749]

I'm looking forward to seeing this.  Good luck on it.  Should be a winner.

 

C

[bhunted 887]

I believe 18 is where you begin to get the benefit of the full powder burn in the 308s but could be wrong.

Thought it was 20"... Might have been one reason lwrc stopped doing 18" reprs...

 

 

Sent from my iPad 2 using T2 Pro

[Rob0115 1,107]

The rifle is going to have an 18" rainier arms select match barrel with the PWS PRC 3.0" long comp. I'm waiting for an SR25 barrel nut for the DD rail. I bought it lightly used but it had an AR10 style nut. Even with the extra 20 bucks it was a great deal.

[A-Tech 8]

Thought it was 20"... Might have been one reason lwrc stopped doing 18" reprs...

 

 

Sent from my iPad 2 using T2 Pro

This is correct. Most of the 700 guys that went with a 22+ barrel so no noticeable difference from 20" with velocity, range, or accuracy. 20" has pretty much been deemed the ideal length for .308

[bhunted 887]

Makes sense if you want accuracy... 16" just makes it a battle rifle with better accuracy but not to the full distance. I'm really suprised they even do 16" AR 7.62/.308s...

I know my M1A Socom II was not meant to reach that far out and touch someone but if I were to build one, I wouldn't short change size for accuracy... I do still have my Rem 700 Police Package for that... IMHO...

 

This is correct. Most of the 700 guys that went with a 22+ barrel so no noticeable difference from 20" with velocity, range, or accuracy. 20" has pretty much been deemed the ideal length for .308

[A-Tech 8]

It's just like the posted muzzle velocity for .223 being around 3250fps..that's measured from a 20" barrel...it's usually closer to 2800ish out of a 16"

[Rob0115 1,107]

Assembling upper. More photos soon.

[2Alpha 6]

I was planning on doing a build similiar to your first idea.  14.5" with either a Surefire or SJC Titan.  Plan is to get a DPMS 3g1.  That way it will already have a nice JP trigger and handguard.  Pull the DPMS barrel, brake and gas block and get a Rainier 14.5 and adjustable gas block.  Selling the dpms parts will help recoup the cost of the better parts

 

I'm not worried about muzzle velocity.  The chances of shooting this gun over 300 yards is minimal

[Rob0115 1,107]

It's complete. range report and photos to follow.

[Rob0115 1,107]

[Rob0115 1,107]

I shot 25 rounds through it yesterday to sight the scope and break it in a bit. It was incredibly smooth for a fairly light 308. Accuracy was tremendous. I shot it free standing 1x power at 50 and the groups were great.