Building an AR

Storz said:

I am mulling the idea of building an AR with the intention to use it for Highpower Service rifle competition..eventually, and just for fun.

I know most of the accuracy (other than the shooter) comes from a good barrel, sights and somewhat less so the upper receiver. Does the lower matter much?

Click to expand...

Not much as long as you buy a milspec lower made of 7075-T6 alloy. Of course the trigger you put in it DOES matter.

if youre going for long range competition, get a match trigger for it.. other than that the lower wont make much difference... a high quality barrel (probably stainless) free floated, direct impinged of course and it should be pretty accurate

The lower does matter less, as mentioned above, but do make sure you get one from a reputable vendor/manufacturer. I've seen some lowers that were just trash. Pin holes out of spec and/or in the wrong places, nasty machine work, horrible finishes and I even ran across and outfit once that was selling receivers made of 6061.

Now the upper, opinions are going to vary. Personally, based on my recent addiction to precision ARs, I'd have to say that the upper does matter. Getting one that is on the tighter side of spec helps with accuracy by keeping things more consistent.

If Service Rifle is what you want to do, maybe your should give Compass Lake a call. Friends into that sort of thing speak highly of them.

If by "building" you mean that you are going to build one from scratch, I'd go with something like a Daniel Defense upper receiver, a White Oak (if you're on a budget) or Krieger (if you're not on a budget) barrel, BCM bolt group and a Geissele Hi Speed trigger.

I would disagree when people say the lower is less important. The lower contains the trigger mechanism, and the buffer. Most people (actually, probably all) who are in shooting competitions drop a match trigger in their lower and twiddle with the buffer until they find the right one. Both are important for helping the shooter get quick follow-up shots on target.

Have fun!

For Service Rifle, the speed of a follow up shot is essentially irrelevant. The lower needs to be in spec. That's it. The trigger is important. The Geissele Hi-Speed Service Rifle is what is used. Compass Lake does awesome precision work and Frank White does the barrels for White Oak Armament. White Oak Precision is the custom side of White Oak and they chamber their own barrels and do their own work. Both Compass Lake and White Oak have really nice setups for pinning and accurizing the sights. Neither are cheap.

As far as the upper itself goes, you need it to be in spec as well. As long as the threads for the barrel nut are cut square to the bore and pin holes are in the right place and of the correct size, you can work with it. Lapping the upper to square the face and true barrel channel are really all that is required. Some precision builders have their own techniques for wringing the last little bit of potential out of them beyond that, but that's the basics.

I have a similar rifle with a built lower (by me) with a Service Rifle trigger and I've started off with a Palmetto State Armory HBAR upper with a removable carry handle for the rear irons. I figured why shoot out a good barrel getting to the point where I'm no longer the limit to accuracy. The rifle is more accurate than I am at this point and I'm into it for less than what just a White Oak Armament "off the shelf" competition upper (without the sight work) would have set me back. When/if I get serious about competing and good enough that the better upper/barrel will actually make a difference, the lower is already built and ready to go.

The lower well obviously need to be in 'spec'. The trigger well need to meet the service rifle minimum weight of 4.5lbs, either single or two stage, most go with a two stage. The A2 sights should be pinned with a NM aperture, oem hand guards can be floated. Topped off with a nm barrel of choice.

There are a few assembly tricks for getting the utmost in accuracy.

I use the RRA 2-stage trigger in 2 of my builds. It's a great trigger for the price. The fit between the upper and lower does have some effect on accuracy contrary to what some might say. If its going to be a match grade target rifle you want a tight fit. Rock River is well known for an extremely tight fit between the upper and lower.

There are tricks for tightening up the upper to lower fit as well.

The picture above is an Open Class High Power rifle. Still no optics but not required to be an "as issued" (at least in appearance) US military issue rifle.