Well, I've had my AR for about a month now and I'm ready to do my first build.  The goal is to build a long range precision rifle.  I would like to do an 18" barrel just to keep it from being completely unwieldy, would a mid-length gas system be a good idea for this length/purpose?

Details aside, the main purpose of this thread is to get a basic idea of what parts affect accuracy the most.  Obviously the barrel needs to be good quality, but should I be looking exclusively at stainless barrels, or are there good chrome lined or melonited barrels for this type of build?  What other things affect the accuracy?  Ie, do I need to buy an upper and lower TOGETHER so they are matched perfectly, does the weight and/or material of the BCG and bolt matter, etc?

The things I'm clear on:  good QUALITY barrel, free float handguard, good 2 stage trigger.  What else do I need to keep in mind when preparing to buy parts?

Stock, something comfortable to you. It doesn't have to be the most expensive one out there but if it is hard to use it will affect your groups.
The highest quality scope you can afford while still being able to put food on the table. You can easily spend 1-3x your rifle cost on glass.
No, on the chrome lined barrel. Usually they are done in large batches. This causes inconsistent quality. You can get "good" accuracy with these barrels, don't misunderstand me (And I'm not knocking any particular brand) but it can affect accuracy.

Just my thoughts on the subject. Have you looked in the precision rifle section?

Stainless barrels are considered the most accurate since the rifling is cut and no material is added or changed to the barrel itself.  Chrome lining adds additional material to the bore, which can be inconsistent.= depending on the manufacturer.  Free floating will only benefit your precision build.  Consider a medium/heavy contour.  It will be a bit hefty, but will help keep groups tight as you heat up the barrel.  Or if it is strictly a bench gun, you can go with a bull barrel with a .936 gas block area and bull contour.

I would personally get a matched upper/lower or at least an upper and lower by the same manufacturer.  I have mixed and matched uppers and lowers before and the best fit upper/lowers I have are matching manufacturing uppers/lowers.  I have a Stag upper and lower that I purchased nearly 3 years apart, and they fit perfectly.  My large frame LR308 MATEN has a great fit together as well.

Like mentioned, a good 2 stage will help.

Otherwise, I don't think you will need much else for a good precision build.  Any BCG should be fine.  An adjustable gas block will help reduce excess blowback for faster follow up shots and to reduce the recoil impulse.  Rifle length gas and buffer will also help give a smoother recoil impulse if you want to go that route.  I have never shot a rifle length gas/buffer, but a midlength gas with carbine buffer is very soft shooting.

How does melonite compare to stainless? Since  it's just a treatment rather than a coating, can melonited barrels be as accurate asstainless assuming it's a quality barrel?

I've had 2 melonited barrels.  Neither one shot worth a shit.  Stainless or CL/CHF only for me from now on.

My opinion on non-optical accuracy components in order of importance:

1. Barrel. Go stainless. 20" is not unwieldy for long range precision work.
2. Trigger.
3. Free float handguard.
4. Stock. Magpul PRS is nice.

Thanks for the advice guys.  I assume 1:7 is the optimal twist rate for this type of build since the heavier bullets tend to be more accurate?

Heavier bullets are not necessarily more accurate.  They do tend to have better ballistic coefficients.  1-7 is fine.  1-8 is fine.  1-9 is fine up to 62 grain for sure and often up to 69 grain.

Quality barrel, free floated with a good trigger and optic shooting good ammunition will get just about everything you can get out of a rifle without really jumping in expense or reloading specifically for your gun.

Sometimes reloading for a mediocre barreled gun can get you there too.

I wouldn't even consider a melonited or chromed barrel if the intent was a precision rifle.  You're likely not going to wear it out.

I have one, and just ordered another.

Care to tell us whose two barrels you have of which niether is worth a shit?

Aero and bergara.

Hmm. Noted and stored.  Thanks.

Note that at no point did i say all their products are bad. Just that the examples i received were far below acceptable standards. It happens, they made it right, I've moved on.

Noted.

May I ask your opinion then of Melonited barrells?  I mean, do you think that that was the problem?

i think it exacerbated things.

if you have a shitty bore, sometimes what's often referred to as "breaking in" will relieve many of those issues and a barrel will settle in and shoot well after that.

with melonited/nitrided barrels, you go through so many rounds *TRYING* (unsuccessfully, usually) to perform the same things "break-in" performs on a naked bore, that it's far better to just cut one's losses and get a better barrel.

that's what was going on with the aero tube.

the bergara, though, that was far shittier times.  fired brass was up to .007" UNDERsized, and I have a sneaking suspicion the chamber wasn't even concentric to the bore.  normally i'd look into maybe having something re-chambered, if it was a quality tube, but a nitrided/melonited/whatever the buzzword is this week tube has such a hard surface, you're destroying tooling just trying to cut the chamber.  end result, you maybe get a chamber cut, but with chatter marks everywhere.  worst case, you ruin tooling AND the barrel, and still have to go buy a new one.  better off just buying a new one.  so i'm going to.

Interesting.  Thanks.

For what it's worth, I have 16 Mossberg Melonited barrel on my carbine  It was very cheap.  I tested the build with 24x magnification and it shot with mil type 55 grain and 62 at around 2 inches at 100 yes.  Not bad I think.  My 69 grain SMK handloads shot about a hair over 1" .  Plenty good for what I paid for it, and I didn't test it with that optic all that much.

It's got an antique aimpoint on it now.  Of course groups opened up considerably.

I just bought a 20" penicle barrel, it's melanited too.  Should be here in a few days.  We shall see what we see.

Pyroclyman touched on one of the most important aspects of precision rifles; ammo. The biggest thing with any precision rifle is repeatability. Hypothetically speaking a gun with a z-shaped barrel (just humor me here) could be a precision rifle if it does the exact same thing EVERY single  time the trigger is squeezed. Run of the mill and bulk ammo suffer on the quality control side which results in inconsistency in POI. So make sure you feed your rifle good match grade ammo that your gun likes. Notice I said that your gun likes, meaning just because it's match grade doesn't necessarily mean your gun will shoot it well.

With that said, everyone else has said is good advice. Free float, 2-stage trigger (Geissele SSA-E), stainless barrel, good stock, etc. Rifle gas will be the smoothest, and I've even read of it increasing velocity a little. This kind of makes sense as the bullet is pushed further before gas is robbed to work the BCG. I also chose a Vltor A-5 system for my SPR'ish build due to it operating smoother, and an adjustable gas block to finish it off.

One final thing I'll add, and start a debate over, is squaring the upper receiver barrel extension. If you're talking precision, concentricity matters. Having the extension square with the barrel can only help.

Most importantly, have fun building it!!

Thanks for the info on the Aero and Bergara barrels...not that I would have ever thought of those as a precision barrels anyway, but good info never the less.

If you are interested in a quality precision melonite barrel, go to AR15Performance ...the 18" fluted SPR barrel is on par with others costing much, much more.

They do carry a 20" non-fluted, but its not always in stock.

I get consistent hits with my 18" out to 700yrds with XM855 and a 1-6x scope...hand loads will likely do even better.

i never said they were purchased as precision barrels, dick.

I was thanking you for the info, since I have not used either, dickless.

I'm in the same boat and doing the same type of build... (And it's my first AR no less! ) .... I've been researching barrels and want to stay at the 18" length,.. for me it's been a toss up between the Wilson Combat and White Oak 18" Fluted barrels,.. Been emailing John @ WOA back n forth the past couple of days and he says I should be good to go with the 18" / 1:7 twist Match grade (SPR) barrel.... 275.00 for the reg. one,.. plus another 100.00 for Fluting. ... this is probably the route I'm going to go.

Rick

I just got this barrel for accuracy purposes:
https://www.primaryarms.com/Odin_Works_18_223_Wylde_Barrel_DMR_Profile_wit_p/b-223-18-dmr.htm

I think I must have ordered the last one in stock though.

Wouldn't the same apply to a chrome lined barrel?

Likely yes, but those examples are of just plain poor quality, not something caused by a treatment or coating.

I decided that I don't need another AR yet, and that I'll be happier with a heavier caliber bolt gun for longer (600+ yd) ranges, so I just bought a Remington 700 in .308 with a heavy contour barrel, HS Precision stock, Harris bipod, SWFA SS 10x42 scope, and Seekins base/rings.  My first ground-up AR build will have to wait until I recover from the $2k I just spent and the $1k I'm about to spend on reloading supplies!

See you in three weeks when the AR-itch comes back.

Did you check to see if your rifle was one of the ones on recall?

Remington 700 Recall

I'm replacing the x-mark pro with a timney trigger anyways.  I pick up the rifle today so I can look for the stamp later tonight (they stamped the bolt release in newer triggers that are unaffected).  If anyone wants a x-mark pro trigger for their Remington 700, shoot me a pm and I'll ship it to you at cost (assuming it is post -recall production).

This.

Look despite what some (uninformed) have said DO NOT be afraid of melonite/tenifer/QPQ/salt-bath nitriding.  A good barrel that is melonited is a good barrel that will outlast any stainless, CM, or CMV barrel, and last as long as a chrome-lined but without risk of accuracy issues that CL has POTENTIAL to have (for all you CL lovers out there).  The melonite is a treatment of the steel.  The steel is heated to below it's curie point but hot enough in the presence of molten salts that allow N and C atoms to enter the steel matrix.  This fills gaps where rust can start and where other things can adhere.  It brings the surface hardness up to the 65+ rockwell range making it last multiple times longer than a standard barrel.  The barrel is slicker, easier to clean, lower coeffecient of friction, lasts longer, resists fire etching, and outlasts everything else.  Short of the black color if you wanted stainless there is NO downside to it.

Glock has done this to ALL their barrels for years.  I had an entire Remmy 700 melonited, everything that wasn't a spring.  1000+ .270WSM rounds later and you wouldn't know the chamber or the rifling weren't new, and cleaning is a couple of dry patches down the tube.  The rifle will shoot clover leaves until you get bored with them, and hasn't changed a lick in well over 1000 rounds.  

In other words, so long as you don't intend any metal work AFTER the meloniting process, the melonite barrel is superior in every way.  What makes it accurate or not is what went into its production BEFORE the melonite process was applied; the melonite itself only treats the steel after the fact.

For an 18" barrel take a look at JSE Surplus:

http://www.jsesurplus.com/18.aspx

I have a JSE upper with a Wilson Arms 18" SS bull mid-length 1/8 Wylde barrel that shoots MOA.

JSE has excellent CS who actually answers the phone.