Tips for building a precision AR?

[gatorgrizz27]

Hey guys, I’ve put several AR’s together so I’m familiar with the general tools and process, but the one I’m working on now if for shooting paper and steel out to 400 yards. Looking for steps/tips that might be less common but could help make it more accurate or consistent.

Parts I already have:

Runner Runner Texas flag lower receiver
Larue MBT 2-stage trigger
Magpul UBR stock
Midwest Industries upper receiver
Midwest Industries Combat free float hand guard
Larue Stealth 14.5” barrel
FN bolt
Toolcraft BCG
BCM Gunfighter charging handle
Leupold Mark AR Mod 1 1.5-4 scope
Leupold Mark AR IMS mount

Still need a gas block and muzzle device, planning on running the SLR Sentry 7 adjustable and Dead Air 3-prong flash hider.

I’m planning to lap the upper receiver face, bed the barrel in the upper receiver with Loctite sleeve retaining compound, and I’ve read torquing the barrel nit to ~ 40 ft-lbs is best for accuracy. Also using a set screw gas block rather than pinning it can reduce barrel stress/stringing. I don’t know if it affects accuracy but I also plan on timing the flash hider so one of the slots is at the 12:00 position and the two on the bottom will hopefully kick up less dirt when shooting prone.

I haven’t seen much about fitting the bolt to the barrel extension other than checking head spacing, or tightening the upper and lower receiver fit. Mines pretty solid, but there might be a playing card’s width worth of slop.

Thanks for the feedback or other things to try/pay attention to.

[sir shovelhands]

Already going way above and beyond by lapping receiver face and bedding the barrel.

I'd suggest a 1-6 optic OVER a 1.5-4, hell if you're shooting out to 400 yards, you might want even more magnification.

Otherwise, reload for it is about the only advice I'd give.

[H-D]

I just completed mine this week. Biggest component for accuracy is going to be the barrel. I went with a Wilson Combat 18" match barrel. It is easily grouping at under 1", but trying to tighten it up a bit with a trigger swap. Trigger is very important too. I had a Geissele SD-E, but just swapped it out for a Super Match because it still felt a little heavy.
Load 77 smk or tmk for it to mag length and you are going to need more magnification for the distances you mentioned. Heck, I went with a Leupold LRP 6-20x50 on mine.

[H-D]

Yesterday's group on right with SD-E trigger and this morning's group on left with Super Match trigger.

[gatorgrizz27]

Thanks for the replies, it seems the Larue barrels tend to be some of the most accurate out there under $500. I also considered the Rainier Match as they have a 1 MOA guarantee, but many of the Larues are around 1/2 MOA.

I’m happy with the trigger as well, it’s a 2 stage so it breaks with less force than a trigger pull scale shows if that makes sense. It’s between 2 and 2.25 lbs from the first stage to the second, I prefer a 2.5 lb pull on my hunting rifles as that’s the point where you’re intentionally squeezing it but not moving the gun for me.

I am a little worried about the 4x magnification on the scope, but shooting paper will only be done at 100 yards for the most part, the longer range stuff will be steel. I didn’t have trouble seeing the 1000 yard targets at Liberty Hill with a 3-9 scope, and was getting and spotting hits at 750 with it.

I’m not going to use anything Vortex makes, and I wasn’t aware of any other reasonably affordable (less than close to $2k) name brand 1-6 or 1-8 scopes. I just looked and saw that SWFA and Trijicon now both make 1-6’s that are under $1k. I picked up that Leupold with an illuminated dot for $350 on clearance, I’ve been really happy with the same 3-9 on my 6.5 bolt gun.

[DocHolliday]

I’d go with a JP barrel and bolt. Look into their barrels. I have a lightweight and it’s solid even after hosing 50 rounds.