AR guys, why is my M4 so inaccurate?
 

I tried to sight in my M4 with Millett Zoom Dot scope today at 50 and then 100 yrds. There was a slight breeze, but nothing much. Shooting from a bench, with my foregrip resting on a carpeted wood block, my red dot at the smallest it could be and still able to see it, I could not hit a quarter-size orange decal on the paper plates I used for targets. I got pretty close at 50 yds., but was all over the map at 100 yrd. WTF is wrong with me? I am normally a very good shot with handguns and my .30-06. Now I've built another M4 and am trying to figure out what kind of sights to put on it. I need to figure out if my highly modded Bushmaster is just inaccurate or if I suck so bad that I need fancy optics to compensate. What can make such a rifle so inconsistent? Seems there's not much adjustment other than the nut behind the wheel.

U need someone new behind the trigger

what bullet weight?

What is the size of the reticle in MOA?

Remember Rick, it is a carbine- hitting a quarter sized target at 50M is very good accuracy for a carbine!

You might get even better results with other ammo. Try different types.

Rick, the #1 thing that makes a rifle inconsistent is the shooter....or poorly stabilized rounds. What's your twist rate, what were you shooting?

Sniper, I think my Bushmaster is the same one you have, XM15-E2S. Is that 1:9 twist? Though the barrel and lower receiver are about the only stock parts left on it. I was using the cheapo steel case Silver Bear today, I think in 55 gr. My scope's reticle is really a red dot that's 10 MOA at its largest and one at lowest. Of course, I tried to make it as small as I could bear, though putting a red dot on an orange decal in bright sunlight was not real easy for me. Next time I'll be using black targets.

I want one of my M4's to be for close work, sort of SHTF home defense and the other for reach out and touch someone work, when I run out of .30-06 ammo - muhahahaha. Kinda thinking about putting this Millett scope on my new one and keeping my Bushmaster for close-quarters stuff. I have a killer 700 lumens taclight/grip with a laser built into it. But I like carrying it for a flashlight. Just can't decide what to do here.

This may sound stupid...but are your scope rings tightened down?

Rick, is that a new sight? I know it always takes me a long time to get used to new optics. maybe you just need to get used to it?

I've had this scope for two years and figure I have close to 1000 rounds with it. I'm pretty sure it's snugged down. I had Noah's M4 Superlight a few years ago, nothing more than iron sights and it was super accurate. I shot everything standing up with nothing to rest against and was still killing ultra thin steel fence posts way far away. I think it's something with my rifle.

Did you damage the barrel crown? A nick or something to affect the exit trajectory?

When you say you were all over the place, was it random dispersion of POI?

I've never shot the Russian stuff, but I hear they aren't great for accuracy. You might inspect the rifle barrel (and scope) then try a different type of ammo.

When I am doing range safety work at the South Bay Rod and Gun Club range in Delzura (near Chula Vista) I see a lot of M4s and/or AR15s that have issues. They are usually caused by the following, not in any particular order: cheap or poor quality ammo, shooting 5.56 in a rifle chambered for .223 (works the other way), bullets are wrong for the twist rate, bullets are wrong weight or profile, trigger is not setup well or the trigger pull is causing the gun to move when squeezing and finally the head spacing is off for the chamber. I would address these in order of ease, get a few match quality bullets to see what happens, try iron/peep sites since a good shooter can hit to 300 yds easily with them. Chack the barrel and make sure the ammo matches what you have for the barrel. Finally check the trigger and make sure it is smooth, even with no creep and breaks clean.

If you are holding the dot on target at 50yds then you will have to adjust for 100 and that can be a problem. Make sure that the site has been mounted correctly so if you move the dot vertical then it goes up and not at an angle. I bought a Wheeler scope mount kit and it was well worth the price and on my red dot I use the magnetic levels to make sure that all is well. I also have a bore laser sighter and use it at night before going to shoot to make sure that the scope/red dot is lined up okay with the adjustments about in the middle at 50 yds. If they are already to one side then the mounts are not correct or there is a problem. Good luck with it.

any slop between the upper and lower? Maybe you need an accuwedge. Also, how secure is your butt stock? Maybe your carbine just doesn't like that brand of ammo...

Was just waiting for this! Coming from the Tabdula the Great, its even better! :)

Bro, near "quarter sized" accuracy at 50m with crap ammo is excellent accuracy for a carbine.

The wide dispersion at longer range does seem problematic though- what sized groups were you shooting at 100m? Was it under 2"?

I would try again with XM193 and a few other brands of ammo- i suspect the problem was just poorly QC controlled ammo.

Of course, I adjusted W & E when moving to 100 yds. I started at 50 because I couldn't remember if I had shot that rifle since I'd last removed the scope. When that was pretty close, I moved to 100. My groups were probably in the 4-5" range at 100 yds. I had a spotting scope to check the targets after each shot. It was pretty embarrassing. Who are these guys who can shoot good groups at 300 yds. with iron sights? I want what they're having.

To qualify in the Army you have to be able to hit pop up silhouette targets at 300m with an M-16 or M-4.

Before i got totally wigged out, i would try again at 100m with some quality ammunition, preferably a couple different brands.

With XM-193 or M855 you should be able to shoot 2.5" or less at 100m with a carbine. When you find "the" ammo for your specific carbine you might get that well under 2" at 100m. It really makes no sense that your groups quadrupled in size from 50 to 100 meters.

Also, if you're having problems next time, let someone else try- see if they can do better. If they do a lot better, it's time to start re-checking yourself for poor fundamentals(it can happen to anyone over time).

PS: AR's should be zeroed at 25 meters.

Was their a loose nut behind the trigger? I'd start with the castle nut. ;)

I can't shoot distances without optics either. Anything past 25 yards and I'm lucky to hit the paper with iron sights.

Hell, if I had known that, I could have saved myself some ammo and aggravation. I can easily hit targets at 100 yds. I just like to be able put them all in the same hole without it getting too big, as I can do with handguns.

When you zero your AR at 25 meters with XM193 you have a MPBR of 330 meters (in a 20" M16A2, less for a carbine). IOW, holding on the center of the target, all your rounds should be in an approx. 12" circle out to about 330 meters.

All 5.56mm combat rifles should always be zeroed at 25m.

MPBR explained: http://www.rmvh.com/MPBR.htm

Just find the ammo that shoots the smallest group at 25m, zero it at that range, and you're good to go.

Ok, I need to do some ammo shopping and then figure out what to put on my new build, take them both to the range and get it all sorted out.

Rick, you might also seriously consider going with a drop in match grade trigger. That makes a bigger difference in real world accuracy at the ranges you're going to be shooting than any other change to the weapon you can make.

http://www.gunblast.com/images/Timne...s/DSC01937.jpg
Timney drop in trigger

http://www.parts4ar15.com/mm5/graphi...001/TR-C2C.jpg
McCormick single stage "tactical match" grade trigger. (This is the one i have)

People always buy optics over a trigger, but IMO that is a novice mistake. A smooth, light, consistent trigger is the single biggest upgrade you can make on any spoon.

I did put a RRA two-stage trigger in my new build. Of course, it came with the spring reversed and RRA's website instructions sucked. Good thing I had another M4 laying around to look at. I haven't shot the new one yet, though.

A good, crisp, light pull makes all the difference in the world.

PS: I agree with checking the castle nut on the breech end of your barrel, by the way. Make sure it's tight. Same for the optics mount/rings too.

You're shooting minute-of-felon. (Morrigan Consulting Home Page) Me says you're good to go.

25 meter zero is 2" low at 50.

LOL@ minute of felon. :D

As mentioned, I wouldn't expect anywhere near 1 MOA (1" @ 100 yards) accuracy with cheap ammo. Add a mil-dot scope to the equasion (even with a 1 MOA reticle), and I would expect even less. Before tearing into it, grab some decent ammo and BZO it with the iron sights. I'd only get suspicious of the rifle itself if you can't get repeatable results with the irons and decent ammo.

Agreed.

LOL. Yeah, I think that's the "quick n' dirty" BZO they teach at Gunsite here in AZ (zero @ 25M with the bigger 0-2 rear aperture). The new high-speed-low-drag method appears to be modding the rear sight to bottom out at 6/3 (on a flat-top) -4 clicks, as the new 200M setting (8/3 -2 on a fixed handle M16). Then zero (adjusting elevation w/ front sight only) with the small aperture @ 50M (POA/POI). This will give you a happy coincidence @ 200M.

We zeroed at 25m with the long range aperature IIRC. It's been so damn long now.

Not to insult anyone here, but it has always struck me that the AR15 / M4 "black rifle" crowd is probably the least in touch, of the whole shooting world, with what is required for good rifle accuracy.

An AR15 can be a wonderfully accurate rifle. It used to be impossible to win a high power match with one, shooting against M1A's, but the tables have now turned. It's pretty much impossible to win unless one is shooting an AR15 these days. There are some exceedingly accurate, high grade rifles available on this platform. The varmint shooters love them, and they will keep up with many dedicated, heavy barrel bolt guns in the field.

I think these specialized rifles have led the black rifle camp to believe the AR platform is an inherently accurate one. I think many expect any rifle or carbine built on this platform to shoot well. Sorry folks, but that's just not the case. The ones that are built to over-the-course or varmint accuracy standards are a far different animal than standard commercial grade or mil-spec rifles and carbines. The requirements are entirely different.

With the autoloading rifle, one can typically have dead accurate or dead reliable. Not both. Target competitors and varmint shooters won't have anyone shooting back, so dead reliable is not an issue for them. Hell, some over-the-course guys actually use ammo that is too long to fit in the magazine, and single load them for 600 yard slow fire. They are using their AR's as single shots. Even with ammo that fits in the magazine (for 200 and 300 yard rapid or timed fire) I've seen guys have to tap the forward assist damn near every shot. Can the military or police afford this compromise in the name of accuracy? Of course not.

Minimum chambers with fire-formed brass is one key component to rifle accuracy. Autoloaders have a hard time with this combination, often failing to go fully into battery. Generous chambers with small-ish ammo (per SAAMI specs) are key to feeding reliability. Accuracy suffers a great deal in the name of reliability. In light of that, I don't think there is any problem at all with your M4, or with your shooting. You just need to dramatically lower your expectations, understanding the intended use of your little carbine.

I largely agree Jeff, as i said in an earlier post, shooting a quarter sized group at 50m is excellent accuracy for a carbine.

4-5" at 100m is too much though- something is going on there. A MILSPEC 16" carbine should be in the 2-3" range at 100 meters with either M193 or M855. If you have a 1:7 twist barrel and can effectively stabilize 77gr OTM rounds at 100m, you should expect to do even better. Perhaps as low as 1.5"

My 1:9 CAR shoots Double Tap 77gr OTM rounds into an approx .5-.6" group at 25yds. This is waaaaaaay more than enough accuracy for what any of us needs a carbine to do.

.5-.6" groups mean 25yd "hostage shots" with ease, and even at 50m, you're still going to be capable of a high level of precision. When are any of us ever going to shoot someone over 25yds, let alone 50yds away?

XM193 shoots even better in my assault spoon, with 25m groups just over .3"

That means 100yd "hostage shots" are possible (though i'd certainly want magnified optics for that).

It's a 16" carbine guys....you can't have compact size and light weight and reasonable price and still expect sniper like precision(though to 100m....you pretty much have it with a good trigger, optics and shooter)

Another thing about carbines, they kick a heck of a lot more than 20" AR's. Way more muzzle rise. And the muzzle flash is immense. And they give up several hundred feet per second of velocity, and quite a lot of energy at any range to a long barreled AR too.

For a self defense weapon, a CAR with 77gr cannelured ammo is almost impossible to beat. It's tremendous blend of compact size, light weight, high firepower, highly effective fragmenting round, low penetration of media makes it great for close range fighting....but it's not a long range weapon.

Ok, I really need to go ammo shopping. I still wonder why I was able to shoot Noah's superlight Bushmaster carbine so well. I forget the loads, but they were from Georgia Arms and I was foolishly trying to burn through it all before I moved to AZ. I'll be using black targets and quality ammo on my next range trip.

Georgia arms is really high quality ammo i think. Noah might have trigger work done to his, who knows.

Rick i'd get 3-4 brands of ammo, the stuff you'd most consider for whatever your intended purpose is. Ie, hunting, defense, plinking, whatever.

Test it all, see which works the best. Next time at the range, try 3-4 more loads.

Rinse and repeat until you have a winner.

Like you said earlier, sniper, what Rick is getting accuracy-wise from a carbine with "crap ammo" is about all that can be expected. Good quality commercial or military ammo should cut group size substantially, like down to the 2-3 MOA range. Handloads using brass fire-formed in that particular chamber will help even more, but at some risk to reliability.

"Horses for courses" is kind of what we are looking at here. One would never expect a 12 pound, 26" bull barreled bolt gun with high magnification optics to be a viable self-defense gun, or a useful entry weapon. Conversely, one should not expect a light, handy little carbine to be a 500 yard sniper weapon. Both have their place. They represent opposite ends of the long arm spectrum.

As usual, agreed.

Different tools for different jobs.

Rick your 1:9 barrel's optimum bullet weight is 69-70 grains. I'm shooting 77's in my 1:9 for effect, not for accuracy. Half inch groups at 25yds is way more than enough accuracy for CQB.