for any guru's here,,,,  how would you list in order of importance things that contribute to increased accuracy to a fairly stock build.

stuff like

new barrel?
matched bolt to barrel?
extension tightness?
bolt and bcg brand/alignment? mods?   how important is bcg tilt?
barrel itself/chamber reaming? who does it the best?
polishing assorting parts, feed ramps, bolt fact to barrel, locking lugs, stuff like that.

perhaps there is already a thread, i can't find it if so, the search thing doesn't work that good for me

match barrel and bolt from reputable company
select twist rate based on preferred ammunition then tune with hand loads

matched receiver set CNC

match trigger from reputable company - Larue MBT is best bang for buck right now

Geissele ssa-e trigger for precision
Criterion barrel

thanks,,,,
i am always wondering,, what is it about a matched bolt and barrel that makes it more accurate.  is it the "headspace"?  it can't be the alignment because the bcg aligns the bolt and the upper/extension aligns the barrel, right?    it seems sad that you could have a super expensive barrel from say bartlein and then buy a complete bcg from someone like jp or lmt and since they aren't matched it would seem like a waste of money?

Spend most of ur money on match barrel, scope, light trigger/2 stage. Go with the best deals on everything else

You can get really down in the weeds on this, and to varying extents tons of things are relevant to precision, but the heart of a rifle is its barrel.

1. A great barrel
2. A great trigger
3. A great scope

The rest, I think, is arbitrary. There is always going to be play between upper and lower receivers and a great barrel with a well-cut chamber can mitigate play in the BCG, to a point.

Barrel, scope, trigger

The barrel makes your rifle accurate.  The scope and trigger make you accurate.

Bartlein, Hart, Kreiger, Brux offer excellent cut rifled barrels.  Lilja, Criterion, Shilen offer excellent button rifled barrels.

I prefer a two stage in my semi auto precision rifles.  The Geissele high speed national match goes in all of them. Thats the only one I can adjust the second stage down to 8-10oz and still be drop safe.

I'm a fan of the mega arms receiver sets for precision rifles, but they've been bought out by Zev Arms.  Don't know if quality is the same.  The ambi bolt release allows me to settle behind the rifle, get on target, and then release the bolt without removing my support hand.

Single most important factor is the barrel, itself.  Get the best barrel you can afford.  Everyone with sub MOA rifles will have their pet choices.  The best chance of getting a sub MOA barrel, especially a sub 1/2 MOA barrel will be purchasing directly from one of the nationally prominent benchrest custom barrel makers that also makes drop-in AR barrels to the same standards as their national and international championship competition barrels.  That short list, in no particular order, would include Kreiger, Lilja, Broughton, Shilen.  My choice was Lilja.

Next, is proper installation.  Shimming, if not a tight fit, possibly squaring the receiver face.  It this is done, any stripped upper from a reputable company will work fine.

I don't see bolt as an issue, if you check headspace and its in spec.

All else goes to permitting you to use the inherent accuracy without human factors degrading it.

That means high quality factory match ammo or match grade handloads that the barrel likes.  No two barrels will have the same optimum load preferences.

A match trigger or two stage trigger with a light and crisp second stage is important.  It does not increase inherent accuracy.  It just helps you in not degrading it.

A good free float rail is important, but does not, itself increase accuracy, it just helps you in not degrading it.

Same thing with the optic.  It has nothing to do with inherent accuracy, but you can't optimize the accuracy if you can't see where the point of impact will be and maintain that point precisely from shot to shot.

I don't think the MBT is a match trigger.  It's a good general purpose trigger and incredible value, but for precision shooting you want a lighter and crisper second stage.

Barrel, scope mount, trigger. You can get by with a midrange scope, if you don’t have a solid mount, and repeatable if you want qd, you will waste a lot of time and money trying to get the gun to group well.

excellent advice, thank to everyone who responded.

more questions have cropped up.

i really like those mega monolithic uppers.    i am trying to decide if weight is a factor here.    for those of you who have done both,    have you noticed better accuracy with a monolithic upper like lmt or mega?

let's say i went with a billet matched upper/lower from like aero.    then a reasonably lightweight handguard  like odin,  sticking with a 24" barrel and a magpul prs stock.   the LMT 6.5 LR's look awesome but are fairly heavy at 12 lbs i think.  but in this set up/application,  it would seem weight is your friend  (other than hiking long distances with it which i don't think will happen)    but how much lighter would an aero component build be?

also,   i am beginning to think that, is it worth it to build my own, can i save an $?    the LMT's seem reasonably priced.

whoever has built a bartlein barreled,  monolithic or billet creedmore with other high end components,   jp buffer,  high end bcg/bolt,  what have you wound up pricewise?   i know i could go add it all up but surely someone has just built one on here.   might know off the top of their heads.

i am definetly not buying a jp long range set up, that is crazy expensive!

any newer calibers out there that  are better than the 6.5 cm for the ar10 platform?.   i do reload so,,,

This is my list as well.  I think matching a bolt to barrel is important, but if it is a common caliber, and a reputable company, I think they chamber fine.  The barrel does the most work followed by the trigger in my experience, the glass just makes seeing what you want to see easier

Dont get caught up in thinking you're going to improve accuracy with fancy names, monolithic this or that, special buffers, special bolts, or a 24" barrel. Just stick to the basics. Like I and others have said, spend money on barrel, trigger, and scope. And even then, you can still find quality for good prices. For example, I have a Wilson Arms 18" Bull barrel - paid $225. RRA varmint 2 stage trigger - paid $80. Nikon scope - paid $250. PSA lower, PSA handguard. LUTH stock. This thing will shoot the flea off a dogs back at 100 yards.

In the AR15 world, you frequently dont get what you pay for.

A large frame will have a higher cost than a comparable small frame.

I built my 6.5cm over time to ease the pain.

$500 mega matched upper and lower
$600 Krieger 22" barrel
$460 JP FMOS bcg
$100 SLR sentry 9 ago
$280 SLR 15.5" ion handguards
$250 Geisselle hs national match trigger
$50 lpk parts
$60 ambi safety
$200 magpul ubr gen 1
$100 slash heavy carbine buffer
$20 tubbs flatwire spring
$12 gas tube
$30 magpul miad
$90 PWS PRC brake
$85 Raptor charging handle
$320 atlas bipod psr

This is from memory so the prices may be close.  Bought some of it during sales.  Total somewhere just south of $3k.

You could save money on the receiver set and other bits.  Large frame rifles can be finicky.  I had some trial and error to include bcg and handguard.  If I were you I'd stick to a stock that permitted the use of a5 or rifle buffers.  Tuning mine to run with a carbine buffer was a bit of a PITA.

I haven't weighed it, but it isn't light.  The barrel alone is ~4.4lbs.  It's perfect for long range prone shooting, but I wouldn't want to tote it through backcountry for long periods.

I've fed it a steady diet of 140eldm, 130gr Berger hybrids, and 142smk handloads.  The barrel loves all three but I shoot the 142s best at longer ranges.