I have an AR I've been tinkering with. ARs aren't typically my thing, but they're so cheap an popular nowadays it's hard to resist.
I've been fiddling with it off and on for a while, put it together cheap a few years ago. It's mostly run-of-the-mill parts like DPMS. I had a friend get a barrel for me that he said was better than average and should be accurate.
About the best it would do is 1.25 to 1.5" groups at 100 yards. No, that's not terrible, and I don't NEED anything better, really. I never shoot past 100 yards (no access to longer range), and I'm not a hunter or an "operator". I have other rifles that are more accurate anyway, but I like to tinker so I thought I'd see what I could do. I picked up an A2 stock kit at a show to replace the wobbly collapsible stock. I bought a $100 Geissele trigger when they were on sale at Brownells. I bought a better scope mount and put a spare Leupold scope on it, instead of the Bushnell Banner I was using. I tried a variety of bullet weights and loads.
How does it shoot? Consistently 1.25" to 1.5" groups @100yrds. No improvement at all. So I get looking at the barrel my friend said was a good one known for accuracy. It's a Red X Arms barrel. A quick Google search tells me that I'm probably lucky it's as accurate as it is! So now I'll be looking around for another barrel, a decently accurate mid-length barrel on a reasonable budget. Either that or be happy with it as it is, but having already spent the other money on it, that seems a waste.
I went through this kind of thing many years ago. I bought a Colt HBAR back in the late 90's. I was disappointed with it from the very start. No matter what I did it just wasn't terribly accurate. It was a 2moa rifle at best. I ended up putting a different barrel, trigger, and free-float handguard on it, and it shoots a good 3/4moa now (about the limits of my abilities).
It always gets me when I some internet expert talk about how their M4-style carbine will shoot sub-moa "all day long", using bulk fmj ammo. I'd like to see that.
Anyone have a suggestion for a good mid-length barrel that won't break the bank? Am I likely to need a .223 chamber to get the accuracy I'd like, as opposed to the more common 5.56? Am I likely to end up going to a free-float handguard too? I don't need competition bench-rest accuracy (would be wasted on me anyhow), but something capable of consistently better than 1moa would be nice.