FNG building first AR-10A

AngelDeVille · January 24, 2015

Hey all, I came across this site looking for parts for my newly acquired upper and lower set.

I have built a few AR's and I was on gunbroker one night and hit the buy it now on a Matrix Aerospace set.

So far I have decided to buy an A2 stock and the LPK direct from Armalite.

I still have some confusion on the barrel/BCG options and free float handguard compatibility, but I'm sure they'll be answered soon enough

FaRKle! · January 24, 2015

Welcome!

I still have some confusion on the barrel/BCG options and free float handguard compatibility, but I'm sure they'll be answered soon enough

The barrel extension and BCG must be of the same pattern (either both LR-308 or both AR-10 pattern). Technically, you could get away with mixing some parts within the BCG, but it's easier just to keep it all the same pattern.

Since you have an AR-10 pattern upper receiver, you'll need an AR-10 pattern rail. The threads on the upper receiver for the barrel nut aren't the same between AR-10 and LR-308 patterns.

What would probably give you the most options is getting an LR-308 pattern barrel and BCG but using an AR-10 pattern rail (must, since the AR-10 upper receiver threading).

Wilson Combat, Centurion Arms, Troy, Midwest Industries, and others make AR-10 pattern rails.

Edited January 24, 2015 by FaRKle!

AngelDeVille · January 24, 2015

Thanks so much for the information, that makes a lot of sense, Midwest was on my short list for the handguard anyway, they make a nice guard with just a top rail.

I'm not looking to break the bank with this build, I already have glass in mind, now to cruise the site sponsors for an 18-20" barrel and BCG.

She will get shot out too 1000 yards quite regularly, and I have a few thousand 180gr projectiles just itchin for the opportunity.

planeflyer21 · January 24, 2015

Welcome from AZ!

unforgiven · January 24, 2015

Welcome from Indiana brother,no one looks to break the bank it just happens over and over again. :))

AngelDeVille · January 24, 2015

Yeah already have most of my parts picked out and I'm over $1,100. So much for cheap!

Edited January 24, 2015 by AngelDeVille

AngelDeVille · January 24, 2015

The LGS has a DPMS complete rifle for $900 I was almost tempted.

edgecrusher · January 24, 2015

I believe you'll be better off building. You'll use parts you want and learn more about your rifle that will help you down the road.

AngelDeVille · January 24, 2015

Yeah that was my thought as well, it was more of a flat top mil spec type, and after I change a few parts around I won't have exactly what I want, and it will cost the same.

So far from Armalite I'm getting the LPK, A2 stock/buffer/spring set and the charging handle.

I have picked out an 18" LR 308 fluted barrel mid length with an LR BCG, LR gas block and tube.

The handguard will be the Midwest 15" with the ar-10 nut.

I was looking at the Armalite scope mount but it didn't give enough info, it just said it was for up to a 50mm scope, and I don't want to fool with spacers for the 30mm, I have bushnell peppr on another rifle that I like.

Im assuming the forward assist and ejection port door are not AR/LR specific.

Am I missing anything?

Edited January 24, 2015 by AngelDeVille

edgecrusher · January 24, 2015

Sounds like a great start

AngelDeVille · February 4, 2015

So I have everything on order and I'm out just over 1k for the whole thing.

I now have everything but glass, rings, and a Turner sling. But I plan to steal that from my varminter Ar15 for now.

I should have all parts in hand in the next 10 days or so, I'll keep you posted!

I hope Brownells gets my preordered mags here in time, or I have a fancy semiauto single-shot rifle.

Thanks for all your help!

BLKSHEEP · February 4, 2015

Welcome from Louisiana

I haven't tried but I think I remember reading that the 180's may have an OAL too long for the mag <dontknow>

AngelDeVille · February 5, 2015

Welcome from Louisiana

I haven't tried but I think I remember reading that the 180's may have an OAL too long for the mag <dontknow>

Good call, mags are supposed to fit up to 2.875" and I'm at 2.80". I got room to spare!

We'll see how it works out in practice..

AngelDeVille · February 7, 2015

I picked up the upper and lower today! Looks really good, it was a blem set, and the only thing wrong were some dings on the upper rail where my BUIS will sit anyway. There could be some other things I could pick on, but it's really nothing I care about.

I still have to put the LPK and the buttstock on.

So I have a question, I was reading that the only difference between the ar15 forward assist and the ar10 was the spring.

I assembled the FA using ar15 parts and it looks like it's good. Am I missing something?

AngelDeVille · February 7, 2015

Well I'm almost fully assembled, my LPK came with a bolt cotter pin instead of the safety detent spring, and I'm guessing they aren't interchangeable......

98Z5V · February 7, 2015

So I have a question, I was reading that the only difference between the ar15 forward assist and the ar10 was the spring.

Not true. Where did you read that?

AngelDeVille · February 7, 2015

Not true. Where did you read that?

When I first headed down the AR10 road, I read as much as I could about them, and the differences between the Ar10a, AR10b, SR25, and the LR308 and it was in one of the many articles I read by Internet " experts".

It didn't make sense to me, but who am I to question the experts?

I gained a lot more knowledge just joining here.

Rsquared · February 9, 2015

According to Armalite's website, they use the same part number between the 10 and the 15. Are you sure you have an "A" model? I didn't think that you could get stripped uppers and lowers yet.

http://www.armalite.com/catitem2.aspx?Category=93c41860-4ca2-43ee-8ca9-dc09b1a5bf2c

Parts 25 and 26 on the exploded diagram.

Edited February 9, 2015 by Rsquared