I am thinking about buying a M&P 15-22 to use for the tactical class for the 3 position CMP shooting. With the 3 position shooting you can use a sling for the prone and seated positions. A friend let me borrow his M&P 15-22 to try it. I got the gun sighted in at 25 yards. I put the sling on and went into prone position. My first 3 shots were low, 1.75", and to the right 1.50". I re-adjusted the scope and brought the group back to center. After firing about 25 shots all staying in a fairly close group I removed the sling and went back into prone position without the sling. The first 3 shots were high by 1.75". I re-adjusted the scope brought the group back to center. It looks like the sling is moving the barrel. The sling is attached to the forearm and the round "nut" has been removed from the end of the forearm so there is lots of clearance between the forearm and the barrel. I was very surprised that the groups were moving as far as they did. I did not have the sling very tight. I have the sling much tighter on my CZ 452 that I use for other CMP matches. I shot the rest of the day with no sling and the groups did not move again. So it looks like the sling pressure is causing the groups to move. I am left handed with the sling on my right arm pulling from left to right.
What could be the problem? I cannot live with that much movement in the groups with sling and no sling. Any help would be great.

Roger L

Move the sling mount back and shorten the sling perhaps. You'd still be able to wrap your forearm, you just would grip in front of the sling post.

That should make the sling flex less on the hand guard.

Make sure the barrel is tight.I sent a scope back because it would not hold zero,but found out a loose barrel nut was to blame.

You do need to check the tightness of the barrel nut but the handguard is sandwitched into place by the barrel nut so if you put press on the handguard you r still putting pressure on the barrel and that will move the poi .. if your going to shoot comp. There r better weapons on the market.. a ruger or a cz are 2 that r hard to beat but a kimber or remington 40x would be a better suited rifle for the job..

Hope this helps

__________________
07/SOT2
NRA Instructor

A loose barrel nut would cause some deviation. Is the scope mounted on the upper, the forearm or straddling both? If the scope is on the forearm or the forearm and the upper, you will have movement, even with a tight barrel nut.

The scope is mounted to the upper only and is secure. I will need to look at the barrel nut. I already shoot a CZ 452 American and CZ 452 Lux for the open and scoped classes of the CMP shooting. I am looking to try the tactical class.
Thanks for the input.

Roger L

Sling pressure always causes a barrel to bend unless the barrel is free floated. You can do this with the M&P15-22 by removing the front modesty handguard plate and connecting the sling point to the handguard.

The handguards will flex noticeably with a tight National Match type sling position, but the flex shouldn't be transmitted to the barrel.

-- Chuck