I have acquired a new DPMS 16" H Bar, non chrome, 556 chamber with a 1 in 9 twist barrel. What should I expect for accuracy with Match grade ammunition? This will be a RRA Flattop, Bushmaster Lower with A2 Buttstock, Bushmaster Bolt/Carrier, and an old beat up 4x12 Leupold. If it shoots real well it will get a float tube and a match trigger and hopefully this will be the end of this one.

If you're a good shooter, you can easily expect <1 MOA with that gun. Probably even without match ammo.  

+1

1MOA sounds possible if you do your part.

WIZZO

Thanks for the response, if this configuration doesn't go well under M.O.A I will be somewhat dissapointed. Do I need to consider one of the Varmint uppers?

Just put together a DPMS 20" No-Ban A3 HBAR 1-9" Southpaw upper with DPMS lower. Found first 100 rounds of associated ammo great than one-inch groups, more like three inch circles. Bought some surplus XM193 Saturday and shot another 100 rounds to find that my groups where 1/2" are less at 100 meters. Real happy with my purchase after 200 rounds and 100 cleanings.

Quoted: I have acquired a new DPMS 16" H Bar, non chrome, 556 chamber with a 1 in 9 twist barrel. What should I expect for accuracy with Match grade ammunition? This will be a RRA Flattop, Bushmaster Lower with A2 Buttstock, Bushmaster Bolt/Carrier, and an old beat up 4x12 Leupold. If it shoots real well it will get a float tube and a match trigger and hopefully this will be the end of this one.hr

One quick word regarding "mixed parts" rifles....  (sorry, I can't resist).  With different barrel, upper and bolt/carrier, I'd run a set of headspace (go, no-go) gauges through it.  But that's me.

Regarding this and the post about the new A3 DPMS, it does take a couple of hundred rounds for things to settle down.  I'm a fan of "break in" in a non-chromelined barrel.  I also hand lap mine (sheesh!!, lol).  

Either way, you ARE on your way to an accurate rifle, and moving in the right direction regarding more accurate ammo.  One of the best compromises of $$$ and accuracy in factory loaded is Black Hills Remanufactured (Blue Box).  It's available in many bullet weights and configs (55gr ball, lighter hunting, and heavier 68 & 69 gr match.   Before I began reloading, I even shot BH for High Power matches and it shot as well as I could.