i think its time for me to build a full size rifle. my question is would a bushmaster 20' government profile 1:9 barrel be accurate (like sub MOA) or would you guys suggest anything else. i trying to go with a more military type rifle look so i really dont want anything stanless. (except for the SPR barrels but those are pricey)

All AR have a chance of being Sub MOA rifles, but the key/starting point is the barrel.

In regards to production produced barrels, the sun does shine on a dogs ass every now and again, but you would have better luck at winning the lottery in regards to finding one that will print sub MOA.

Simply put, you need to focus on a great custom barrel, then the parts such as sights, ammo and so on in regards to achieving the Sub MOA from the autoloader.  In regards to most of the target type barrels that are production produced such as the SUM, somewhere hovering at MOA in more of the order (if everything else is up to snuff).

To sum it up, most production rifles produce anywhere from 1 to 3 MOA on the norm with target ammo. To go SUB, you into custom rifle territory.

To add: Match ammo will be in order to even get close to what the rifle will achieve, with hand loaded needed to wring the most out of the rifle.  Do not expect to burn cheap ammo out of the rifle and get the desired groupings that you are seeking.

check out krieger (sp) or WOA

Quoted: ...the sun does shine on a dogs ass every now and again...

HAHAHAHAHA!!!  Made my day!  

What Dano523 is correct.  It boils down to barrel, brass, and bullets: the 3 B's.

I have never used Kreiger or Douglas AR barrels, but many high power shooters swear by them.

I, personally, have two mounted (and one in reserve) White Oak Armament SPR barrels.  These do perform sub-MOA with Sierra 69 and 77 bullets.  I use Winchester brass/primers and IMR-4895.

Edited to add:
You will need a box of tacks to drive.  

ok thanks but one more question do flash hiders/ comps effect accuracy

not that you will notice, barrell should have a 15 / crown

Quoted: ok thanks but one more question do flash hiders/ comps effect accuracy

Yes, but to what extent is pretty much dependant on the attachment.

If you want a tack driver, leave muzzle attachment off.

As Raven_Fire stated, a good crown is important.  It is the last thing to touch the bullet.

   I just purchased a 16" SS 1/8 barrel from model1sales and it shoots great. here is a pic of the first three shots i fired out of it. The distance was 75 yards and my platform could have been better, so i expect this rifle to shoot about half moa. Ammo was BH blue box 60 gr SP so that could be better as well. If you dont want the SS look paint it black.  IMHO you dont need to break the bank on expensive custom barrels to get sub MOA accuracy. Some will say M1S is a crap shoot, but everything i have ordered from them has been great and from what i hear they have good customer service. For the price i just dont think i could do any better. A friend of mine has an armalite match 20 inch SS rifle, and he couldnt beleive this barrel and its accuracy at that price.

would i also have to match a bolt assembly to the barral

Matching the bolt is really not nessesary. Unless the bolt has seen so much use that its worn then it would probably be better to buy a new bolt and carrier. I just use the bolt that ive had in my upper. Its the third barrel its been on and obviously it works just fine.

I have an ER Shaw .223 1 in 9 twist 4140 20" HBAR from M1S and it shoots .5 moa with 55 gr all day. All M1S barrels are ER Shaw. I would send picture of group but have not got this picture thing down yet.

Quoted: would i also have to match a bolt assembly to the barral

Every custom barrel maker request that you supply a bolt or they will provide one to head space the chamber, every one states that you do not need to but it does help to know that it will be headspaced to the exact round you desire.

Flash suppressors if installed at the time of the barrel turning and of high quality will not degrade accuracy at all, just screwing any POS on it will not help. I have built every configuration imaginable for a match upper and if done properly it will do just fine.

If you do not intend on reloading your own ammunition as others have stated, just purchase a quality upper and save some bucks.

Quoted: What Dano523 is correct.  It boils down to barrel, brass, and bullets: the 3 B's.

+1  What do you plan on shooting out of your tack driver NRose8989?

well i mainly shoot blackhiils 55gr fmj

Quoted: well i mainly shoot blackhiils 55gr fmj

Well, that rules out the last 2 B's listed above, so you don't really need to worry about the barrel.
A typical 20" 1:9 will suit you just fine.
If the sun shines right, you might get a good one.

The key to accuracy is a properly centered throat.
Production barrels are made on CNC lathes that (necessary for tool safety) have excessive clearances between the reamer pilot and the bore.
As a custom maker, I fit a pilot to every bore to ensure a perfectly centered throat.
Nothing else is as important as this.
Everything else still needs to be good stuff for it to be a shooter, but a poor throat is the one thing that will spoil ANY barrel blank.

When you want a seriously accurate rifle, first start reloading.
I taught a guy some tricks and he was able to get consistent 1/2" groups with a factory colt barrel.
The sun was shining that day when colt made that barrel
Now he is having me make him a Krieger barrel because he wants to consistently shoot 3/8" sized groups...

Drop me a line when you are ready for a custom barrel, that's all I do...

As for the fit of the bolt to the barrel, it's NOT just the headspace.
There is also the endspace.
This is the distance between the end of the barrel and the locking lug faces inside the barrel extension.
Typical military specs call for about 0.010" clearance here.
You can tighten that up a LOT.
What you gain is that the brass will not get sized as much while chambering.
Think about this...
The bolt is flying forwards, hits the rear of the cartridge, slides the cartridge into the chamber where it stops against the shoulder of the cartridge case.
Now, the bolt continues forward while the extractor snaps over the case rim.
Then the bolt bottoms out against the case head the the bolt starts to rotate as the bolt carrier bears on the cam pin.
These forces DO resize the case in the chamber.
Tightening up the endspace (fitting a barrel to a bolt) will reduce the sizing effects because the bolt lugs will come to bear on the rear of the barrel instead of on the case head.
The benefits are mostly to the reloader, if you are leaving the brass on the ground, it does not matter as much because your ammo was sized per SAAMI specs, not per the specs of your chamber.

Randall Rausch
www.ar15barrels.com

Quoted: Quoted: well i mainly shoot blackhiils 55gr fmj Well, that rules out the last 2 B's listed above, so you don't really need to worry about the barrel. A typical 20" 1:9 will suit you just fine.

That's kind of where I was going with the question, but Randall_Rausch explained it much better than I could have.

I've got a Fulton Armory Legacy Rifle with a USGI 1x12 pencil barrel, and it will shoot XM193 and Q3131A better than they are supposed to shoot (2 MOA dispersion spec. IIRC) at 100 yards.  I typically get groups under 1.5" with the iron sights and my 42 year old eyes if I take my time.

Black hills might have less variation than XM193 or Q3131 - I don't know - but the ammo is probably more of a limiting factor than the barrel.