First AR Build...Need help with precision build.

[bbush]

I have recently gotten the AR-15 build bug and wanted a little help before I get started. I already have a Colt AR-15 that I shoot regularly, but was wanting to build a precision AR for more accurate range work out to 500 yards or even further. Before I get started, I am trying to decide where to cut cost corners and where to not to. I know that I shouldn't cut any corners with the barrel and trigger, but is there any other part that needs to be the best that I can afford. I plan on ordering a Krieger barrel and a Geissele trigger, but do I need to be as concerned with the brand of the bolt, upper receiver, lower receiver, etc.? Do I gain anything from going from a Anderson lower receiver to a more expensive lower receiver such as Spikes or even Noveske if my ultimate objective is an accurate build? Does the brand of the upper have anything to do with a guns ultimate accuracy? How much affect does the brand or type of bolt have on accuracy? I noticed that there are complete bolt carriers, enhanced bolt carriers, and nickel boron bolt carriers...any difference in the accuracy department? I am just trying to make informed decisions before I start ordering parts and realize that I should have gotten something better after I have received it. Thanks for any replies back.

[Eurodriver]

1) This is the wrong subforum for this question

2) You're on a good road with the Geissele and Krieger. I'd also recommend a BCM M4 upper or a MUR. Something that fits the barrel more tightly can only help accuracy.

3) I don't believe the bolt/carrier has any impact on accuracy, and the lower certainly doesn't either. However, depending on what you end up getting there could be tolerance issues between the upper and lower. A quick search of this forum will yield SMEs explaining that a wobble between the upper and lower can and does negatively affect accuracy. If you're building an SBR with a chrome lined barrel shooting minute of man, it won't matter. But when you're measuring things in tenths of inches it can. With that said, I would try to find a lower that fits the upper without wobbling before I put the rifle together.

4) A stiffer rail would probably help with loading a bipod and may affect the barrel nut less, but I have no quantitative evidence to support that.

In short, as long as the parts fit properly, I would consider anything other than the barrel, upper receiver, and trigger a "nice to have" feature, but not a necessity.

[OrbitalE]

A quick search of this forum will yield SMEs explaining that a wobble between the upper and lower can and does negatively affect accuracy. If you're building an SBR with a chrome lined barrel shooting minute of man, it won't matter. But when you're measuring things in tenths of inches it can. With that said, I would try to find a lower that fits the upper without wobbling before I put the rifle together.

This is a scenario where buying a "matched" receiver set from the same manufacturer can come in handy. Not sure how folks feel about Accu-wedges, but that's an option too.

[GH41]

I have recently gotten the AR-15 build bug and wanted a little help before I get started. I already have a Colt AR-15 that I shoot regularly, but was wanting to build a precision AR for more accurate range work out to 500 yards or even further. Before I get started, I am trying to decide where to cut cost corners and where to not to. I know that I shouldn't cut any corners with the barrel and trigger, but is there any other part that needs to be the best that I can afford. I plan on ordering a Krieger barrel and a Geissele trigger, but do I need to be as concerned with the brand of the bolt, upper receiver, lower receiver, etc.? Do I gain anything from going from a Anderson lower receiver to a more expensive lower receiver such as Spikes or even Noveske if my ultimate objective is an accurate build? Does the brand of the upper have anything to do with a guns ultimate accuracy? How much affect does the brand or type of bolt have on accuracy? I noticed that there are complete bolt carriers, enhanced bolt carriers, and nickel boron bolt carriers...any difference in the accuracy department? I am just trying to make informed decisions before I start ordering parts and realize that I should have gotten something better after I have received it. Thanks for any replies back.

Do you have the tools necessary to build the upper properly? If not you will save $$$ buying it assembled. If you get an assembled upper get with a matched bolt. One less thing to worry about... second guessing your decision. Have you thought about the scope and mount? How much have you budgeted? Why do I ask?? Because you will have $2,500+ invested in a top shelf upper, trigger and mid to low priced optic. Why would you worry about cutting corners to save a few hundred bucks on the lower assembly? Think about it. BTW.. What twist Krieger barrel are you looking at?

[556BlackRifle]

If you want to build a match grade AR while cutting corners - I won't say it can't be done but, a little luck will go a long way. The parts that you choose and the way the parts fit and interact together make all the difference in the world. If you buy from a well stocked local shop, and they let you do some test fitting of parts, this could go a long way. You want:


A tight fit between the upper and barrel such that when you slide the barrel extension into the receiver, there is no looseness. Also, there should be no gap between the receiver and barrel extension where they meet up. Check the mating surface at the front of the receiver where it meets the rear of the barrel extension collar.
A good fitting upper and lower receiver set is also a good thing to have. Billet sets that are made by a reputable manufacturer may have a slight advantage but you can find a forged set that mate up perfectly well.
You will need a good free float system to support your rifle without affecting the barrel. Whichever rail you choose, make sure there is adequate clearance between the rail and gas block and make sure that the rail extends long enough to rest on bags or a bipod.
Select a good pistol grip that provides an angle that feels good to you when shooting from the bench or prone.
Select a stock that can be adjusted for length of pull and comb height. Many options here. Magpul PRS, LMT DMR come to mind but there are many others to choose from.
Select a charging handle that can be easily reached around your scope. Something like the RA Avalanche with Tac Latch handles would be a good choice here.
Optics and mounts is a whole other topic but also a very important consideration.



Bottom line is, unless you get lucky (I'm living proof that you can) building a long range precision AR isn't going to be cheap.

Good luck!

[MistWolf]

Fit between upper & lower doesn't matter. If it did, you'd have to re-zero your AR each time you separated the two halves. The best device to take up any slop between the two halves is a loaded magazine.

Billet receivers cost more, weigh more and add nothing to performance.

The heart of the AR is the barrel & bolt. Get a good quality barrel with a matched bolt and at least 90% of what needs to be done about mechanical accuracy has been accomplished. Installing a free float tube will take care of the rest. Sometimes it helps to square the face of the upper before installing the barrel.

The VLTOR MUR upper receiver might help as it's stiffer and had less flex