5 MOA!

I shot my AR-15 again today. Yesterday I got keyholing and weird performance at 100 yards with 40-grain bullets, so today I shot 50-grain Fiocchi Extrema rounds with V-Max bullets.

Yesterday, along with the keyholing, I got inconsistent accuracy, and because I managed to put nearly all of 9 rounds in one big hole, I don’t think I’m the problem, nor do I think the gun is incapable of shooting well.

Today, things did not go well at all. I didn’t get keyholing as far as I can tell, but grouping was so bad, I quit and took the gun indoors to see if I could find any loose screws on it.

Here is the first target. I always start on the bottom-left bullseye and go clockwise. I shot at each bullseye 5 times.

The first group looks like a 1.5-MOA group plus a flyer. Could be worse, as the second group, at top left, shows. The next group, at top right, looks like it’s centered around a different point of impact. The last group looks about like the first one, except that it’s centered below the center of the bullseye.

Here is the second target. Before I shot it, I fiddled with the scope’s parallax knob. I thought it could be the problem. I find it hard to adjust parallax out from a prone position.

The first group is wonderful. I thought my problems were solved. Then I tried to hit the upper-left bullseye, and it was like one of the scope’s rings had broken in half. I would call it 4 MOA, but that makes it sound better than it is, because one round hit the top-right bullseye. The highest hole in the top left bullseye looks like it may be a keyhole.

I didn’t try to put a group in the top-right bullseye. I shot at the one on the lower right, and at first, I thought I had missed completely. I had to go look at it. I stopped shooting. I can’t shoot when I have no idea where the bullets are going. I know I’m not going to hit a cow or miss the berm, but spraying and praying is not good practice.

Seems to me that the 5-round, one-hole group proves the gun and I can shoot. You can put 3 rounds in one hole by accident, but it’s not nearly as likely with 5 shots, and the other day, I put most of 9 shots in one big hole. So something is wrong.

Someone suggested the barrel nut might be loose. I took the handguard off the gun and looked at the nut, which turned out to be a special nut that works with a regular wrench (yay). The nut was very tight. I looked to see if the gas tube was hitting anything. I looked at everything I could think of.

Finally, I looked at one of my magazines. I saw an article about AR accuracy problems, and it mentioned magazines. The writer was talking about feeding issues, but it occurred to me that a bad magazine might damage bullets.

When I checked the magazine, I saw that it had sharp metal edges in front of the bullets, and the edges were shiny. It looked like they had brass or copper on them. I shoved a cartridge forward, and sure enough, the bullet hit the edge. I looked at a bullet, and I saw a couple of little marks on it. I don’t know if it was damaged badly enough to make it fall apart in flight, but I didn’t want to take chances. I cut recesses in both magazines so the bullets couldn’t touch them. I have some plastic magazines, and they were made with these recesses.

It amazes me that anyone would make a magazine that shaves metal off cartridges, but there you go.

I don’t know if this is what’s causing the accuracy problem, but it can’t be helping. I ordered a couple of short plastic magazines to replace the cheap metal jobs I modified.

After considering everything else, I have to think about the scope. It may be defective. Something inside it could be rattling around. I may put another scope on the gun and shoot it to see what happens.

This really looks like a 0.75-MOA gun, with the right ammo and good concentration. The gun and I can do 1 MOA if I can get the bugs ironed out. It’s very obvious that something other than user ineptitude or a fundamental gun problem is at work. No one goes from a 1″ group to completely missing the bullseye in one day without some kind of unusual mechanical problem.

The more I work with this gun, the more I realize the AR platform is a mess. It’s practically a religion. These guns have all sorts of problems unique to the genus, and you have to buy special tools to work on them. I can’t discount the fun, though. Buying an AR is like buying a puzzle. Making it function is part of the joy.

I may put a different scope on the gun tomorrow. If it shoots well, all this fuss about other sources of inaccuracy will prove to be a total waste of time.