I just got a Bushmaster lower with some type of "Pre Ban" aftermarket upper. It looks pretty good, very much like a pre ban HBAR without a chrome bore.... Questions?

1. Is a 1.5" group too much to expect from a barrel of unknown origin?

2. Should I trade the upper in its unfired condition for genuine Bushmaster or Colt (or other) upper
before its fired.

3. Alternately, should I try my best to squeeze what I can out of it, and expect the best and accept the worst and trade it in after it's been fired?

4. Is there any way to find the maker of the upper?  The ONLY marks on it are "0 (RI) 9" on the front sight.

5. Finally, If I DO decide to work with the current upper, and I find it's not up to my needs, short of replacing the upper or barrel, are there any accurizing tricks on the AR design?

Anyway...

I've been into accuracy for a lot of years, and just recently the need for a reasonably accurate service rifle became necessary and I know that neither of my two mini 14's will do the job. I had very little experience with AR's and this one fell in my lap at a really decent price, good enough to work with it financially.


 TIA for any guidance,

          Gary

Barrel marked in any way?

Odds are this.  The barrel is by Brand X manufacturer.  My guess is a 1:9, and you can measure this with a wooden dowel and a patch.  Ask your local gun shop/gunsmith about how to measure barrel twist.  After that, if someone has a bore scope, take a peek at it and see if there is anything wrong with the lands and grooves.  Beyond that, the upper doesn't mean crap for accuracy.  On AR's the barrel, the fit of the barrel and the fit of the bolt to the barrel nut is everything.  The fit of upper to lower has NOTHING to do with the rifles accuracy.  Who makes the upper doesn't mean antyhing.  It's the barrel 99% of the time.

I left out good ammo on purpose...'cause it's obvious.  

After checking the twist rate and the condition of the barrel, go buy some good ammo.  Black Hills is great and cheap.  Hunker down and shoot it!  That will tell how accurate it is.  We can talk about my barrel maker and my gunsmith, or Joe Snuffy's barrel and gunsmith.  In the end, does the damn thing shoot?  Take it to the range and send some lead down it.  

Good luck with it.  You're venturing down a road where addiction is the standard and obsession is key.  The AR is one of the greatest rifles EVER invented.

SPC Richard A. White, Senior Medic
249th MP Detachment (EACF)
Camp Humphreys, ROK