Help me learn about ARs


August 26, 2010, 07:23 PM
I've decided that my knowledge of AR's is sorely lacking and the best way to learn more about them is to build one. I'd like to put together a nice varmint/bench gun, probably chambered in .204 Ruger. I have a lot of the big items (Krieger barrel, Magpul PRS stock, Krieger free-float handguard) picked out, but I'm at a complete loss when looking at uppers, lowers and part kits. I'm certainly interested in recommendations, but what I'd really like to know is what I should be looking for. Does Mil-spec matter for a bench gun? Are forged lowers reliable or do I need to get one machined from a billet? What differentiates a good parts kit from a bad one? I don't think I need/want M4 feed ramps but maybe I'm wrong. These are the things keeping me up at night.

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August 26, 2010, 07:34 PM
I'm not saying you won't get quality information on THR, but if you haven't already, you may also want to go to the interweb's largest forum for ARs:

There's a bunch of bs on there like any board, but there's also quite a few posters that seem to know their stuff...

August 26, 2010, 08:46 PM
For components like the barrel, Mil-spec is detrimental to a bench gun. Non-chromed bores should be more accurate and barrel profiles can be stiffer. Feed ramps won't matter to you, but won't hurt anything if you end up with them. For the parts kit, I bought the cheapest that I could find and it functions well but the trigger pull is very creepy. You already have very good parts so DO NOT cheap out on the trigger.

Forged receivers have been components on fine AR rifles for decades. Billet is rumored to buy you better tolerances that you may/may not notice.

Hope that helps so far

August 26, 2010, 08:47 PM
Does Mil-spec matter for a bench gun?
Mil-spec shouldn't mean much to a bench/target/varmint gun.

Are forged lowers reliable or do I need to get one machined from a billet?
Forged is adequate, especially for lowers. Accuracy lives in your upper receiver, not your lower. Get a billet upper if you really feel you must have one.

What differentiates a good parts kit from a bad one?
The quality of material and manufacture of the parts in it separates good from bad. Stick with a well known manufacturer, and don't just go after the bargain. Stag, Daniel Defense, DPMS. Pick one of those and you'll be good to go. Get a good trigger (i.e., not the one that comes with the LPK).

I don't think I need/want M4 feed ramps but maybe I'm wrong.
A bench/target/varmint gun doesn't need M4 feed ramps, but most flat top upper receivers are coming with them these days. They're not going to hurt anything, and it's not worth going out of your way to find a receiver that doesn't have them.

Good luck with your build. Post pictures when you're done!

August 26, 2010, 09:14 PM
As has been said, military doesn't engage varmints much. I can't think of any mil spec id want on a varmint or bench rifle

Forged has some advantages but theoretically billet uppers are a little stiffer which would be advantageous for a varmint gun.

Either feed ramp is fine as long as you make sure the barrel and receiver match.

White oak sells quality parts kits at a reasonable price.

August 26, 2010, 10:10 PM
Jon, keep us posted on what you find and how your build goes. Lately I've become pretty fascinated with the idea of a .204 AR build myself, but it'll likely be a few months before I can get started. Good luck, and we hope to see some pics as it progresses!

August 26, 2010, 11:29 PM
You certainly rattled off the right names for the barrel and stuff. The most important parts of the rifle are going to be the barrel and bolt. You can pick just about any upper and lower receiver and be good to go, as long as they are from a quality company and as far as the receivers go, milspec is a good thing. I've toyed with the idea of getting a billet upper for my precision rifle, but don't see any reason to. They are bulkier and I don't need that. When you order your barrel, get them to sell you a bolt headspaced for the barrel. Doing it this way will get you a more precise fit between the barrel and bolt. I didn't do this. I just used a milspec bolt and carrier from Bravo Company and my rifle shoots sub MOA groups. Since you're getting an "oddball" caliber, it might not be a bad idea to just get the matched bolt and barrel set.

Since you are building a precision rifle, get a quality lower parts kit, or maybe you can just scrounge the parts necessary to build the lower, minus the fire control group. I say this because most lower parts kits come with a crappy fire control group that you will wind up just tossing into the parts bin. For a precision rifle, you're going to want a good trigger. JP, Timney, Geiselle, etc. Look to spend between $200 and $300 for a very good trigger. Unless I'm mistaken, Adco Firearms will put you together a lower parts kit to include a nice fire control group. Give them a call.

All of that having been said, building an AR is not the best way to learn about them. The best way to learn about them is to get one and learn how to maintain it. You'll pick a lot up from just doing that.

I know that ARs are pretty much just erector sets, but there are some little tidbits that can and will affect accuracy. There are also things that can pop up and if you don't know how to handle it, you could ruin an expensive parts. If you just feel the need to build something, build yourself a lower. Those are hard to screw up. Then just buy yourself an upper or have one built and slap it on the lower. I've never done it, but I hear that White Oak puts a nice upper together.

I won't say that I've built hundreds of ARs, but have built about a dozen of them and have torn down and put back together a bunch more than that.

The only other advise I can give you is not to get a railed handguard unless you really need it. A free float tube is much more comfortable for shooting offhand and they are much more rest friendly. I used a Bushmaster freefloat tube for my precision .223 build. It came with a bipod stud and a rather thick barrel nut that gives the tube a lot of stability.

August 27, 2010, 09:40 AM
Anyone with the mechanical ability to R&R a waterpump on their car can build an AR. What they can't do is assemble the upper with the precision techniques to make sure it will shoot that way.

Much of the tolerances for building an AR allow random assembly of parts without further checks, and the casual builder has that privilege because military specs are the standard. It's included in the price, AR's aren't known to be cheap as a class of gun. Getting an upper correctly assembled for accuracy isn't going to happen on a kitchen table, because there are a number of gaging and finishing operations that involve high precision tools, techniques, and the knowledge of what they are. Most makers of high precision rifles don't tell us what their proprietary processes are. It's their livelihood, and if you want the results, buy the better assembled uppers and enjoy the guaranteed accuracy.

Any AR parts kit will teach someone how it assembles, but it doesn't teach how it works. That delves into gas timing, buffer weights, barrel lengths, what happens during the operation cycle, and what problem areas the design has - because some compromises were made. One is the straight magazine well, another is that the milspec standards only require 2MOA accuracy. Another is that it's a combat rifle. For a precision shooter, the sling cannot be attached to the barrel, it doesn't need chrome, M203 cuts, or even milspec rifling. The center charging handle will be awkward if the left arm is slung up tightly, and some precision shooters then have right side charging handles installed. Most uppers like that delete the forward assist.

Anyone can buy all the parts and get a decent shooting rifle, tuning it to get it better takes experience and a skill level high enough to open their own business.

August 27, 2010, 09:52 AM
tirod brings up a good point. before you order the barrel, make a decision about what weight varmint bullet you're going to shoot (e.g. 40, 45, 50, 52, 55g) and tell krieger so he can put the appropriate twist in the barrel.

August 27, 2010, 05:09 PM
Wow, great info so far. I was going to ask a follow-up question of whether I should build the lower and upper or just the lower, but it sounds like I have my answer. My intention now is to purchase a billet upper and a bolt assembly and send it all to Krieger to have them do the install. They did an M1A for me a while back and I was very happy with it. I'll be using their handguard and gas tube. If I can get a .204 barrel, I'd go with the 1:12 twist, since I pretty much only shoot 32 or 35 grain bullets. If I can't (see below) I may either go with .223 or try a different barrel manufacturer.

As for the trigger, I did a bunch of research last night after reading TonyAngel's post. Normally I wouldn't post things from other forums, but I found a good comparison of AR triggers here: I was going to try living with a stock trigger but now I've changed my mind. I think I'm going to go with the Geissele trigger, either the SSA or the Match.

Here's my next batch of questions.
1) Who makes billet uppers? I haven't seen many other than the VLTOR MUR.
2) Should I care about a forward assist? It seems like it wouldn't be a big deal to not have one on a bench gun.
3) People have mentioned getting a matched bolt and barrel. Sending in my bolt and having a custom barrel made is the same thing right?
4) I've heard about changes in charging handle design lately. Is something like the BCM Gunfighter handle useful on a bench gun?

(A note on Kreiger AR barrels in .204)
I emailed Krieger yesterday and asked if they could do one for me. Their response was that they do not do individual orders on these because of the difficult set-up. They do make small production runs for different gunsmiths and when they do they usually make a few extra, so I may get lucky and catch one.

August 27, 2010, 05:17 PM
let krieger sell you a matching bolt. you just need the bolt carrier

if you go geissele, get their "hi-speed" match trigger, not the SSA for a varmint gun. The SSA is more reliable but not nearly as crisp as the match trigger.

1. LOTS of people :)
2. no
3. possibly, but easier to just let them do it unless you want something special

or you could ask them which gunsmith ordered a run lately and call them

August 27, 2010, 05:32 PM

I just had an AR in .204 Ruger built. Take a look at my thread title My new AR in .204 Ruger.

I would recommend AGAINST building the upper yourself. Some may disagree, but headspacing the barrel can be tricky. You will need some special tools to build the upper. I would leave this to the pros. When you order a barrel from the manufacturer it should include a matched bolt but I would still shy away from this.

I bought my complete Ruger .204 upper from White Oak Armament and I am quite pleased. You may want to look into a 1:10 twist barrel. Mine shoots the lighter bullets but it will also give you the flexibility to shoot heavier bullets. Keep in mind that some 1:12 twist barrels will not stabilize 40 grain bullets.

I was going to build my lower myself, but Ranier Arms assembled exactly the components I wanted for $25.00. A lower can be assembled with a simple punch set, but there are a few specialized tools that will make the job go smoother. I will likely assemble one down the road. On this build, I didn't want to screw up my beautiful billet lower.

Good luck what ever you decide on!


Zak Smith
August 27, 2010, 05:34 PM
We have a whole section of AR15 references in the second post in the tacked thread

Please do your homework there before posting more questions.

August 27, 2010, 06:00 PM
One milspec component I'd normally go with even in a bench rifle is the bolt carrier group - from BCM, DD, etc. But in your case with the .204 I think you've gotten good advice going with Krieger.

Sounds like you're going in the right direction!

August 27, 2010, 08:20 PM
For billet uppers, check out Ranier Arms. They sell good stuff. As for the trigger, you can get one of the Geiselle High Speed line. I like the DMR because I think it will serve well in the field for those times when you're not just on the bench.

I was running a Geiselle SSA trigger with a JP 3.5lb spring kit, but it was lacking in terms of being used as a trigger for a precision rig. I was getting ready to order the DMR, but was hesitant because I really hate adjustable triggers. I almost started leaning toward a Timney, but really wanted a Geiselle. Well, what do you know? Geiselle just released the SSA-E. It's supposed to be as rugged (and is non adjustable) as the SSA, but with a pull weight and break closer to that of the DMR. It's was only $200 too. I ordered mine from Adco.

August 27, 2010, 10:38 PM
4) I've heard about changes in charging handle design lately. Is something like the BCM Gunfighter handle useful on a bench gun?

The Gunfighter CH is designed to accommodate forcefully cycling the bolt from the port side as part of the modern manual of arms for fighting rifles. The extended latch of the larger size would be helpful in charging the gun around the eyepiece of the optic, but there are add-on latches to the standard CH out there which may be lower cost.

August 28, 2010, 01:51 AM
There is more to the Gunfighter charging handle than just having the extended latch. They was it's designed, the roll pin doesn't bare (or is it bear?) all of the pressure when you pull back on it. I have the one with the large lever because the ocular bell on my scope makes charging the rifle awkward.

August 28, 2010, 01:58 PM
Exactly, the GFCH was designed for a type of charging that a bench/varmint gun isn't really going to be subjected to. A standard CH with an extended latch is adequate.

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