View Full Version : New build, could use guidance/ resources
I am relatively new to the world of AR builds (I've put together one with help) and I am struggling with my inability to find new resources and information.
Specifically I am starting down the path to build an AR10. I was thinking of going with a 308, and my preliminary research found that a barrels ideal length for that round is 22" to 24" but the sites I've been looking on max out at 20". So either I am failing at research or my few go to sites are failing in their supply. Any help in directing me to knowledge or a better retailer would be much appreciated.
Additionally I can't seem to find a good source on the break down of standard things like gas system length, and how it correlates to the diameter at the gas block or even if it does. Every time I think I find a good source it breaks down to speculation and vague references that infer a base knowledge I don't have yet.
I feel like someone that was just handed a tape measure and the whole world of carpentry is laying open for me to learn but I can't figure out what the hell someone means when they say 14 7/16+.
I?m not going to be much help but I will point out that you don?t necessarily have the same standardization across AR-10 platforms like you do with the AR-15. Things may have changed but for the longest time you had parts for the Armalite pattern rifles and parts for the DPMS rifles and not everything was cross compatible. While AR-15 parts are based off of military specifications based off of the M-16 there is no mil-spec for the AR-10.
Saying this as someone who has built an AR10 and has owned other 308 ARs. Don't build one, just buy a factory built one. The amount of troubleshooting and parts compatibility issues when building one is not worth it.
You'd probably be very happy with a 20" Ruger SFAR or LMT 308 depending on your budget.
Scanker19
02-10-2024, 08:37
If you stick with all parts from the same manufacture you’ll, in general, be fine. It’s when you start mixing parts is where you find trouble.
AR-10s are a PITA...mine runs great, BUT it's heavy, ammo is expensive (compared to 300blk or 223/556), GOD forbid something breaks (parts compatibility), magazine compatibility is yet another issue.
It's a lousy choice for self defense due to weight/size, there are FAR better hunting rifles out there, there are more accurate Target rifles... so the question becomes why?
If you stick with all parts from the same manufacture you’ll, in general, be fine. It’s when you start mixing parts is where you find trouble.
Yeah that's what I thought with my all Aero build (with a BA barrel, which I thought would be fine because Aero owns BA.) Turns out in order to get it actually running correctly, it needed an AR10 buffer tube and regular AR buffer rather than the Aero shorty buffer/carbine tube, a Tubb flat wire recoil spring and a KAK dual ejector BCG. It was a frustrating experience with several range trips of troubleshooting work.
First off, a big welcome to our new member DAD. When I read this post, I was suspicious that I knew who it was. I was correct, and he and I have worked together for a few years. I helped him put together his first AR in 223.
I’m gonna take the liberty of refining his questions. I am actually in the same situation. I have a stripped upper and lower from aero precision, and I’m concerned about my first AR-10 build. I’ve built more 223, 224 Valkyrie, 300 blackout, 22 LR, 6ARC AR’s than I can remember. Neither of us have ever built an AR-10.
An interesting question would be what combinations of components you have found work in 308 or 6.5 Creedmoor.
Details of interest would be:
Cartridge
Barrel length
Gas length
BCG
Buffer and spring
Please chime in with your known good combinations. And make DAD feel welcome. It’s good to see new members!
Welcome to the Forum DAD.
I have only built one .308 AR. It was a complete DPMS 16 inch HBAR upper mated to a compatible lower from a different mfg. even with the compatibility of the parts I still had to do an unreasonable amount of fiddling with it to get it to run reliably. In hindsight it was an interesting experience, but I would not recommend going that route to anyone. It was Pig heavy and not very practical for much of anything.
I reached out to a couple friends that both own LaRue Tactical Large Frame ARs One in .308, the other in 6.5 Creedmore.
Here are their responses to my questions.
1. What are your thoughts on the LaRues you both have?
2. Would you do it again?
3. Better options you have discovered since?
4. Biggest Pros?
5. Biggest Cons?
Friend #1: My 308 Larue has been 100% reliable and does a good job at what I purchased it for: hunting inside 300 yards. That said I cant get to consistently group under 1.25 inch @ 100 yards. It has the light weight barrel they used to make. Running a can Im glad that I got the 16 inch.
ArmaLite pattern (AR-10) has angular cut at rear end. Laure, Armalite, Stoner SR25, Lewis Machine and Tool and Knights Armament Company.
DPMS Pattern (aka LR 308 pattern), aka PMS, this has an elliptical receiver rear end (curved like AR15) and is the more common pattern. Aero M5, Anderson, PSA etc.
A DPMS pattern upper will NOT work on an ArmaLite lower, but the inverse might, I would not mix patterns.
The reason I went Larue was they had a very good quality/price ratio. But they are more spendy than they used to be.
Generally the ArmaLite patterns are more spendy and there are less of them, probably fewer companies making junk rifles in that pattern.
Friend #2: I will echo Friend #1 on the reliability of my LaRue.
I will add that their for-end is going to have better accuracy potential because it does not touch the barrel or barrel nut.
With all that said, if you have AR related questions, stop by Bowers Tactical the next time your down in Centennial and pick Rob, Sean, or Mikes brain for awhile.
Also, heres a couple pieces worth reading.
https://www.arbuildjunkie.com/best-ar-10-build-advice-rifle-options/
https://www.arbuildjunkie.com/decoding-the-ar-10-lower-receiver/
Little Dutch
02-10-2024, 18:07
As for barrel length, if you look around you may find a lot of the bolt action rifles are topping out at 20" now. 18" seems to be plenty good for very tight groups out to 300, which is the farthest I've shot my .308's for accuracy.
That said, if you want to go with a longer barrel I've been very happy with the barrels I've ordered from X-Caliber. The caveat there is that I have only ordered AR-15 barrels. My AR-10 uppers have always been purchased pre-assembled.
https://www.x-caliber.net/ar-10
Good luck to you both on your AR-10 builds.
An 18 or 20 inch barrel with rifle length gas is about the best you can ask for in a 308. Past 20 inches or something like a 260 or 6.5 Creed go with an extended gas system.
Most (but not all) AR barrels use .750 gas blocks.
They are just as easy to build as an AR-15, but nothing is standardized like they are with the AR-15s.
They are also nowhere near as easy to troubleshoot as an AR-15.
They are just as easy to build as an AR-15, but nothing is standardized like they are with the AR-15s.
I will add to this that some, if not most of your AR-15 tooling likely won?t work. The OP can probably count on investing in some tooling if he chooses to build his own.
My advice, stay away from RRA.
BPTactical
02-11-2024, 09:01
OP-
You have gotten some solid advice from some respected and knowledgeable folks.
Knowing what I know about the AR10 platform I would throw a couple of things on the table:
Unless you have a specific configuration you are looking for just buy a factory complete rifle.
If you do insist on building your own and want it to run correctly you are going to have to invest in quality components.
If you purchase quality components you?re not going to save any money.
If you?re not worried about the money buy a LMT MWS or MARS. Switch barrel rifles guaranteed to return to zero when you switch and they RUN.
Thank you all for the advise and articles. Since I started with a PSA lower looks like I'll stick with a full build through them. Ill keep you posted on any problems I run into, and hopefully the solutions as well. Thanks again.
DAD
Great-Kazoo
02-15-2024, 08:00
Thank you all for the advise and articles. Since I started with a PSA lower looks like I'll stick with a full build through them. Ill keep you posted on any problems I run into, and hopefully the solutions as well. Thanks again.
DAD
That's your best option. This way vendors can't say. Well we know our products work, must be the other guys. In my brief time owning a 308, i suggest you buy a few extra sets of gas rings. Find ammo it likes and stick with it, instead of wandering from mfg-mfg. Or even better, if you reload, this way you'll get consistent hand loads after you find that sweet spot load.
An 18 or 20 inch barrel with rifle length gas is about the best you can ask for in a 308. Past 20 inches or something like a 260 or 6.5 Creed go with an extended gas system.
Most (but not all) AR barrels use .750 gas blocks.
They are just as easy to build as an AR-15, but nothing is standardized like they are with the AR-15s.
They are also nowhere near as easy to troubleshoot as an AR-15.
All true. I've been through a bunch of AR10s, and even factory ones can be a PITA to tune. Regardless, you have a PSA lower, so yes, I'd stick with their parts mostly. 18" rifle gas is a great place to start which is not that hard to tune up.
Just realize, most AR15s are overgassed, and eh, most run fine, but they have half the powder charge of the .308. Get a bolt rebuild kit and consider the possibility of getting an adjustable gas block, because yes, PSA .308 barrels have a gas port that is very generous to be able to run the lower power 7.62NATO ammo as opposed to the higher pressure .308Win ammo. The tune is the gas port size, gas system length, buffer spring rate and buffer mass. It's a dance.
Hey Dad, more discussion on the topic over here:
https://www.ar-15.co/threads/192669-308-vs-6-5-Creed
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