Trouble grouping less than 3moa @ 100yards with AR

[Coal Dragger]

Those results at 100 yards with a crude BUIS are quite acceptable. Could a NRA high power or service rifle competitor shoot tighter groups with iron sights? Absolutely. They're also running a match grade barrel, match trigger, heavy fixed stock, and will be using extremely refined aperture sights with adjustments that are rock solid. Not to mention carefully tuned match ammo.

For the OP I humbly suggest upgrading your trigger to a Geissele SSA, or SD-C (I love the SSA-E and SD-E but they're awfully light for a duty/working gun). I put an SD-C in my Colt M4A1 SOCOM II, and without a doubt has been the best upgrade to my practical accuracy with that carbine. If you then want to really see what your BCM can do, you're going to need to invest in some optics. A well set up M4 type carbine with a free floated chrome lined barrel, good ammo, a good optic, and a shootable trigger can easily be a sub MOA weapon. Mine has given me some nice groups with hand loads, even holding under MOA for a 10 shot group. Kind of tough to complain about results like that out of a semi-auto with a NATO spec chamber made to run reliably when hot, cold, wet, dry, dirty, clean, and everything in between.

 

[Takem406]

You're using iron sights??? With my Daniel Defense it'll do a half inch at a hundo with a scope and handloads. But with irons at 50 yards I can get a minute of pie plate and at 100 it's about minute of county. So if you're getting 4" at 100 with irons you're Bob Lee Swagger material!
Also I've noticed my AR is very bullet picky. About the best thing I've found are 60 gr vmax and 68 Hornady BTHP match.

 

[Takem406]

I'd look at a Hiperfire 24C trigger with the lightest spring. That really helped me out. It's like shooting s good bolt gun trigger. Single stage and no take up or slop. Thats how my gun shooting so well.

 

[txblackout]

When people are shooting moa at 100 yards they are referring to resting the gun on a bag. If you are just holding it to your shoulder you shouldnt have any expectation of getting 1 moa.

 

[HEAVY METAL 1]

The advice above of having another person try the gun could be revealing and help if the unsatifactory grouping is due to you or the gun. This happened to a shooter at my local range. He was not getting the grouping he thought he should. He aked me to try the weapon and I was able to cut the group in half. In all fairness to him the trigger was awful.

 

[tallwalker]

I have been shooting National Match High Power service rifle (AR15 iron sights) competitions for a couple of years now. It REALLY teaches you the fundamentals like finding your natural point of aim, properly using a sling, trigger and breathing control, learning wind, etc. I would highly recommend showing up to a match and giving it a try. You will find plenty of good people and all the help you need. Finding the 6" X ring at 600 yards prone from a sling happens with beginners regularly with just a few minutes of coaching. Good luck!

 

[FL-NC]

3 MOA isn't bad with most AR15 rifles with iron sights. 2 MOA is good, and less than that is pretty hard to come by without spending some serious $ on gun, scope, and ammo along with skill.

 

[strambo]

Yep, you are doing fine with that setup. Bag the rear and play with different target types and you could get it down some more. Kinda academic though, no relevance to field position shooting and w/o a magnified scope, still not shooting to the rifle's full mechanical accuracy potential either.

 

[JeffsJeep04]

I like to start with my sights to the left and below my intended target. I will bring the front sight post up alongside the target until it's centered, then move it right to bring it centered. I find it makes me much more consistent not having to guess where center is up and down, being able to find it while seeing the whole silhouette. Not sure if that makes any sense or not, but it sure helps on the qual range every year for me.