Fix for M&P 15-22 barrel flex?

[Crow Hunter]

I have 2 M&P 15-22s.

One of them is set up as a supplemental training rifle with a PA red dot and a sling to mimic my "real" AR.

I liked it so much I got a camoflaged one and set it up with a Leupold 2X7 optic to use as a varmit/squirrel eradicator.

I have found a potentially fatal flaw however.

With the forend resting on a front bag, it will shoot pretty much 1.0-1.5 inches at around 50 yards if I do my part.

However, if I take pressure off the forend by shooting from sitting or standing or even magazine monopod, my groups with drop 3 to 4 inches below point of aim. I can put it back on the front bag and right back to my original zero.

There is "slop" in the opening of the forearm end cap and you can wiggle the barrel slightly with finger pressure. I am assuming that is why the group moves with varying pressure on the forearm.

Is this a problem with the gun or is it just a result of a plastic upper receiver? (I will be contacting S&W to ask as well)

Assuming it is not a manufacturing defect, is this something that can be corrected by shimming the barrel so that constant pressure is maintained?

I really like the weight and handling of the gun and it accuracy from the bench, but I bought this one for "field" use and a lot of my shooting isn't off of bags. It might be sitting/standing braced or prone. I can't 100% guarantee the same upward force on the forend.

I don't know if my other rifle has the same issue or not, I didn't bring it with me this weekend, but I have it sighted in closer and I didn't use bags when I sighted it in. (Magazine monopod prone)

[Littlelebowski]

Odd, we were just talking about POI change here and some folk think having a crisp trigger is more important.

Here's a fix

[mbogo]

I think you will find that your cheek weld and relative eye position are different when you change shooting positions.

Sight in for the position you expect to use most.

mbogo

[Crow Hunter]

Odd, we were just talking about POI change here and some folk think having a crisp trigger is more important.

Here's a fix

This is definitely not trigger related.

I can shoot with it rested on a bag, then monopod it, then back to a bag and on the same bench and it will move repeatably up and down on the target. I can make it go higher by leaning downard on the stock but it only moves up about 1/4" or so. (I could deal with that amount of movement)

It isn't really flyers, it is a group shift. 10 rounds fired at each grouping. The bagged group is much smaller, mostly touching. The monopod group is about 2 inches (hard to balance on just the magazine). If I shoot at a 8.5 X 11 sheet of paper with a 1" square in the center, benched the shots are all in the square, most touching. Off the magazine, the group is barely on the bottom of the paper. I can go right back to the the square buy putting it back on bags.

The new barrel nut that you linked to is really more than I want to spend since I assume you have to then buy a standard AR FF rail.

I don't really need to add anything to the gun, I just want to be able to hit menacing small furry creatures without having to contend with a huge zero shift handheld to braced.

I am seriously thinking about trading it in on a CZ 455 American. (If I can find one)

[Crow Hunter]

I think you will find that your cheek weld and relative eye position are different when you change shooting positions.

Sight in for the position you expect to use most.

mbogo

It is definitely the rifle.

I had my old Marlin 881 with me. I did the same test with it. No magazine, but I shot from the bags on the foreend and just resting it on my upraised arm, elbow on the bench holding it right in front of the trigger guard and I did not see a zero shift, the groups opened up but they still centered around the aiming point whereas the M&P 15-22 dropped 3-4 inches below the aiming point.

I also leaned on the stock hard with the foreend bagged and I didn't see the groups move up.

I can also see the barrel moving on the M&P. I can just push up on the barrel with my fingers and see it oil disappear around the forend cap and when I release, it is visible again.

[Littlelebowski]

This is definitely not trigger related.

I know; my point was that your problem is living proof that POI change from non free floated ARs is real though other folk think it's not a problem.

Were I you, I'd just spend the money on the part I linked to.

[C4IGrant]

I would remove the end cap and see what you get.

Or do what I did: https://www.m4carbine.net/showthread.php?t=118181



C4

[mbogo]

I just checked mine, and the barrel does not move at all when I press on the barrel (of course the handguard end cap might be stiffening the barrel).

The risk of barrel droop on the S&W MP22 is pretty small compared to a Ruger 10/22.

Perhaps the barrel nut is backing out.

mbogo

[Crow Hunter]

I would remove the end cap and see what you get.

Or do what I did: https://www.m4carbine.net/showthread.php?t=118181



C4

You get no change of impact now with different pressure on the handguard?

That is also what LL recommended.

I just hate to spend another $100-200 to get a plastic gun to shoot.

I just checked mine, and the barrel does not move at all when I press on the barrel (of course the handguard end cap might be stiffening the barrel).

The risk of barrel droop on the S&W MP22 is pretty small compared to a Ruger 10/22.

Perhaps the barrel nut is backing out.

mbogo

I have a 2nd one, that I am going to check tonight to see if the barrel will wiggle on it. I didn't have it with me yesterday as I was trying to find out why I was missing low and having to hold over so much with the M&P 22 vs my old Marlin when I was shooting at varmits over the last couple of months. I thought maybe I had knocked the scope out. That is how I discovered this problem.

I will check tonight, if it doesn't move and this one does, I will let S&W know and see if they can help me out or I might just buy a barrel nut wrench.

I assume a standard AR barrel nut wrench doesn't work?

[mbogo]

No, you need a special wrench. Fortunately, it's inexpensive. See shoowrench-barrel-wrench

Good luck!

mbogo