What receiver sets for precision build?

[AMP!]

So, I’ve build a dozen or so AR’s over the past few years, primarily on Aero receivers. Plenty shoot sub MOA. Used one Spikes forged but didn’t notice a fitment or quality difference. I keep going back to @bigjake83 builds and recently @Eurodriver build and want to build a “ultra precise” 223.

I just finished installing a Rainier ultra match barrel in a M4E1 set last night so I’ll see how it performs today. However, this info will help me plan my next build. I’m curious, what receivers you have all had the best luck with?

For those of you who have built these precision AR-15s, your input is much appreciated.

 

[BravoSector1]

Bench/Varmint gun or light weight? Take a look at the 2A armament sets for a very tight fight along with weight savings.

 

[AMP!]

Reliability and precision would be the top two factors. Weight savings is always nice, but not a big factor.

 

[Eurodriver]

I will defer to @bigjake83 as he has more time with this than I do, but I used a Noveske lower and Noveske marked MUR upper (bought separately).

For a carbine, or even a general precision AR the wobble between upper and lower matters not at all. But when you’re chasing 4” gongs at 600y with a .223 I want every possible variable eliminated. Going with a matched set should eliminate this.

What does matter a great deal more than that wobble is barrel fitment in the upper. Squeezing the barrel in the upper as opposed to holding the barrel against the receiver is a better way to go based on my research. That’s the real reason I went with the MUR. I’ve built countless ARs and never seen a more stubborn fit. In fact, when I got the parts cerakoted and had to remove the barrel from the upper it took a rubber mallet and a barrel clamp in a vice to get it off.

 

[Strykervet]

I've built a .33MOA Grendel on an Aero receiver set. I changed it out with a Noveske and MUR1 when I rebuilt it and it shoots EXACTLY the same. The upper and lower are inconsequential to the performance of the weapon and I've seen this in hundreds of these rifles, maybe more. The barrel accounts for most all of the accuracy, a FF tube helps with this, and the BCG generally accounts for a lot of the reliability IME. I used a Satern cut rifle barrel for the Grendel and I tend to use JP Ent. FMOS carriers --slick as shit, even if used dry they still work flawlessly, and the bolts are better quality too.

Bingo, that's it. Pick you stock, tube, trigger and other shit and you're gtg.

That said, I only use KAC and Noveske lowers along with a few LMT's I have laying around. And one SBR'd Mega (yeah, I Form 1'd a Mega, laugh it up). Anyway, truth and honesty, there isn't really a difference between the high end $200 forged 7075 milspec lowers and the $50 for the most part. The more expensive ones can be easier to assemble and tolerances a bit closer and they almost always have a superior finish but that's about it. Oh, a nicer receiver will have a higher resale value if that's important.

A Noveske lower (their new Gen2 lowers are really nice btw!) and VLTOR MUR1 upper (or again, the new Gen2 uppers) will build a very solid rifle that can hold value.

But if budget has anything to do with it, you're better off spending more on a barrel and less on receivers.

 

[padom]

Get a Seekins IRMT-3 upper and their matching mlok handguard or get one of these MEGA SBU Billet thick walled uppers. Both are extremely rigid and perfect for heavy barreled precision uppers.

IRMT-3 Upper

<p><strong>iRMT-3 Upper</strong></p> <p>Designed for extreme accuracy and durability under real-world stress, the iRMT-3 upper receiver allows your barrel to be a true free float system. With the handguard attaching directly

www.seekinsprecision.com

JSE Surplus

JSE Surplus knows guns! Need an AR custom build or repair? Or upgrade your own rifle? Over 60 years of firearm training and a quality selection of guns at fair prices.

www.jsesurplus.com

 

[Back Spin]

@Strykervet did you ever get a chance to shoot that Grendel off a barricade before and after the receiver swap? If so, when you went with the MUR upper, did you at least notice a reduction in POA/POI offset between prone and barricade shooting?

 

[Basher]

I went w/ a Seekins IRMT-3 and the matching SP3Rv3 rail. The way the rail mounts to the receiver virtually eliminates receiver flex when loading the bipod, and the flat bottomed rail rides bags and barricades better than a round (or any other shaped) hand guard does.

 

[bigjake83]

So, I’ve build a dozen or so AR’s over the past few years, primarily on Aero receivers. Plenty shoot sub MOA. Used one Spikes forged but didn’t notice a fitment or quality difference. I keep going back to @bigjake83 builds and recently @Eurodriver build and want to build a “ultra precise” 223.

I just finished installing a Rainier ultra match barrel in a M4E1 set last night so I’ll see how it performs today. However, this info will help me plan my next build. I’m curious, what receivers you have all had the best luck with?

For those of you who have built these precision AR-15s, your input is much appreciated.

What's up Brother...

So give me some insight on how you want this build done and how you're going to use it, is this going to be for long range precision? Or just a Precision AR in general?

I'd be more than happy to walk you through this and help you put together your ultimate Precision AR.

Caliber options, are you going to stay with .223 or are you going to try 6.5 Grendel or 224 Valkyrie? These will also dictate the style and length of barrel you'll need. Basically your Barrel style and contour are going to dictate your receiver set needed.

 

[AMP!]

What's up Brother...

So give me some insight on how you want this build done and how you're going to use it, is this going to be for long range precision? Or just a Precision AR in general?

I'd be more than happy to walk you through this and help you put together your ultimate Precision AR.

Caliber options, are you going to stay with .223 or are you going to try 6.5 Grendel or 224 Valkyrie? These will also dictate the style and length of barrel you'll need. Basically your Barrel style and contour are going to dictate your receiver set needed.

I’d say precision in general. I probably won’t shoot it past 600, but would love to run it at some matches and to be able to hit that 4” gong at 600 Euro is talking about consistently.

And sticking with .223. I was planning on a bartlein from CLE. I’ve had the 224 and Grendel and they’re both great, but I’d rather stick with one caliber for AR15s

 

[Jsp556]

Spend your money on the barrel. Kreiger Direct, CLE, Keystone, etc. BCM uppers have to be heated to install the barrel and are cheaper than MUR’s.

 

[Eurodriver]

Spend your money on the barrel. Kreiger Direct, CLE, Keystone, etc. BCM uppers have to be heated to install the barrel and are cheaper than MUR’s.

See. That’s how mine have always been too but I just put together a brand new BCM4 Upper (ordered from BCM in July) with a Noveske 12.5” SS barrel and it slipped in with zero effort at all.

Kinda has me wondering what’s up with that.

ETA: I agree about the barrel. A hand lapped SS barrel can’t be touched when you really start getting out to the far ranges of .223.

All these button rifles barrels for $150 are cool for punching paper at 100y but I’d love to see a statistically significant sample size comparing the SDs in a button rifles barrel to a hand lapped cut rifled barrel.

Anyone wanna give me about $30,000?

 

[AMP!]

Anyone wanna give me about $30,000?

What kind of barrel cost 30K?! I’ve never bought a higher end barrel, and the enhanced Aero receivers are as fancy as I’ve got. But, I commission in May and that O1E pay is going to be pretty sweet compared to what I’m used to.

 

[Eurodriver]

What kind of barrel cost 30K?! I’ve never bought a higher end barrel, and the enhanced Aero receivers are as fancy as I’ve got. But, I commission in May and that O1E pay is going to be pretty sweet compared to what I’m used to.

A statistical sample size would be about 30 barrels of each type (60 total).

Add in uppers. Rails. Ammo and $30k is a low estimate.

 

[Jsp556]

See. That’s how mine have always been too but I just put together a brand new BCM4 Upper (ordered from BCM in July) with a Noveske 12.5” SS barrel and it slipped in with zero effort at all.

Kinda has me wondering what’s up with that.

If I get one that’s loose, I’ll send it back and pay for a MUR.

 

[bigjake83]

I’d say precision in general. I probably won’t shoot it past 600, but would love to run it at some matches and to be able to hit that 4” gong at 600 Euro is talking about consistently.

And sticking with .223. I was planning on a bartlein from CLE. I’ve had the 224 and Grendel and they’re both great, but I’d rather stick with one caliber for AR15s

I would recommend a CLE Krieger 20" SDM contour rifle length gas, .800 Gas Block, .790 to muzzle, 1-7.7 twist, Wylde chamber, 9/16x24 or 5/8x24 threads.

Rainier Arms adjustable .800 gas block. (This Gas Block is perfect for this handguard because at Rifle Length it sticks out far enough to make adjustments easy and still provides ample clearance because the adjustment screw that protrudes slightly to the right is past the handguard.)

With the LaRue Upper/Handguard set
https://www.larue.com/products/stealth-2-0-receiver-and-handguard/

JP or RCA LMOS BCG

And a PWS Ambi Lower.
https://www.primaryweapons.com/product-url-6793

Rifle length buffer system with luth MBA-1 Stock and JP SCS

Triggers....

Geissele SSA-E

LaRue MBT

AR Gold

Trigger Tech AR Diamond


I've now built three complete rifles with this same build recipe and they have all been sub 1/2 moa.

If you're not running anything heavier than a 20" barrel the LaRue Upper/Handguard Combo is the absolute best choice, it's TRUE free floating handguard system can't be touched when building for optimal accuracy. You can load your bipod or exert external force onto the handguard as much as you want and it will not transfer to the barrel.

 

[AMP!]

That’ll be a solid setup for sure! And good to hear on that handguard. I’ve never used larue parts minus the mounts. It’ll be spring before I get to build her, but at least I can start a parts list.

 

[lennyo3034]

To throw another wrench into your decision:

LWRC SIX8 Receiver Set 6.8 SPC

The LWRC SIX8 Receiver Set is a high-quality receiver set designed for use with the LWRC SIX8 platform. This receiver set is crafted from high-grade aluminum, providing durability and strength while remaining lightweight. The receiver set includes both upper and lower receivers, which are...

grabagun.com

I've been considering building a longer range .223 on a LWRC six8 receiver set. Reason being the six8 specific mags allow loading to 2.390" or longer. That puts the 75 ELDm into contention which has significantly higher BC than any of the 77gr offerings.

If the PRS gas gun series were still alive, I would probably do this to shoot tactical division, but as of now there is no use for this build over a standard .223 or 6.5CM AR, both of which I already have.

 

[ShootnFool8]

BCM is all I have used. Tight tolerances, and every ar built 1 moa or less. Can't complain with BCM.

 

[Nivium]

If you're not running anything heavier than a 20" barrel the LaRue Upper/Handguard Combo is the absolute best choice, it's TRUE free floating handguard system can't be touched when building for optimal accuracy. You can load your bipod or exert external force onto the handguard as much as you want and it will not transfer to the barrel.

What would be the recommended upper/handguard combo for something bigger than a 20"? Or for a heavier grendel barrel, etc.? I've tried the VLTOR monolithic upper/handguard, but its built such that you can't get a lapping tool in there and I like to lap the receiver faces. In my mind, nothing beats the larue

 

[bigjake83]

What would be the recommended upper/handguard combo for something bigger than a 20"? Or for a heavier grendel barrel, etc.? I've tried the VLTOR monolithic upper/handguard, but its built such that you can't get a lapping tool in there and I like to lap the receiver faces. In my mind, nothing beats the larue

The LaRue stealth 2.0 handguard upper receiver combo is definitely the best for squeezing out all the potential accuracy out of a DMR to Recce style rifle but in true LaRue fashion he skimped on some of the critical areas and because of that I wouldn't use anything heavier than a 20-in medium profile Barrel in the LaRue UU receivers. But!! If you can score a PredatAr for a reasonable price you get the benefits of the true free floating Barrel design and the upper receivers are beefier and can handle anything you want.

You're not going to be able to laugh this one either but if you buy a quality brand more than likely it won't need lapping anyway.

IRMT-3 Upper

<p><strong>iRMT-3 Upper</strong></p> <p>Designed for extreme accuracy and durability under real-world stress, the iRMT-3 upper receiver allows your barrel to be a true free float system. With the handguard attaching directly

seekinsprecision.com

 

[Strykervet]

@Strykervet did you ever get a chance to shoot that Grendel off a barricade before and after the receiver swap? If so, when you went with the MUR upper, did you at least notice a reduction in POA/POI offset between prone and barricade shooting?

Sorry... I know it's been a while, didn't see this until now though.

So the only change whatsoever with POI/POA was when I changed suppressors --the TBAC has much less drop than the SDN6 it originally had. The FF tube keeps all the stress off the barrel so no real changes there like with non-FF setups.

The receiver change made zero change and I'd have to sum it up to cosmetics, really. I suppose it makes me feel better though, I do like the MUR uppers, they are solid. None of this stopped me from changing others to KAC lowers when I got the chance (I'm a fanboy, sue me).

I should mention when I did this, I also faced the upper and then loctited the barrel in place. Still shoots the same as it did with the budget Aero set. I wish I could say more about it but I can't...

Always been a fan of Noveske though for the sheer quality, they simply do a basic AR the justice it deserves. Tight fit, shit goes together like it's supposed to --what more can you want? FWIW, their newer lowers are pretty nice too (that rifle actually has one of those too, wider flare for magwell). And they make their own version of MUR1 now but I haven't used any (my cup runneth over with AR's, I don't have optics for all the ones I already have).

That Grendel is still the best shooting rifle I've got though, I'm gonna cry when I have to trash that upper (because once you loctite one in place the whole thing becomes disposable along with the barrel). But whatever. It'll never work loose. Not that I've ever had a URX4 work loose.

 

[Nivium]

That Grendel is still the best shooting rifle I've got though, I'm gonna cry when I have to trash that upper (because once you loctite one in place the whole thing becomes disposable along with the barrel). But whatever. It'll never work loose. Not that I've ever had a URX4 work loose.

Have to ask on this: Why is it trashed when you have to replace the barrel? I shim and loctite my barrels with high strength/high heat green loctite and I have always just torched them and hammered them out with a dowel from inside the upper. No issues that I have seen, but is it considered unsafe to use an upper once a loctited barrel has been removed from it?

 

[bigjake83]

Have to ask on this: Why is it trashed when you have to replace the barrel? I shim and loctite my barrels with high strength/high heat green loctite and I have always just torched them and hammered them out with a dowel from inside the upper. No issues that I have seen, but is it considered unsafe to use an upper once a loctited barrel has been removed from it?

Nope your upper is still GTG, I do the same thing. I think that some people just aren't comfortable with heating up the receivers and beating out the barrel, and are afraid they'll cause more harm than good.

 

[Neurotic]

FWIW Hoppe's cleaner solvent will break down Loctite sleeve retaining compound. If I soak the extension to upper joint for a day or two, they separate without heat.