hedp
11-23-11, 16:00
First a little background. My department ordered quite a few S&W MP15X rifles. When we got them some of them just would not sight in correctly. We checked the ammo and rifles and determined that some of the rifles chambers were too tight.
After much back and forth we found out that S&W had purchased Thompson/Center and were in the process of moving Thompson/Center's machinery over to the S&W factory (or so we were told). In order to boost production and fill orders S&W farmed out the barrels and purchased a bunch from Mossberg. The batch of rifles we had came with some Mossberg barrels and some Thompson/Center barrels. I believe the Thompson/Center barrels have a "-X" on the barrel while the Mossberg barrels have a "xX" or something similar. So the barrels that were having problems with are the Mossberg barrels.
So S&W sent us all new Thompson/Center uppers. We went to the range today and changed out the uppers and all of them shot fine, except mine. Mine made ok groups at 100 yards but they seemed to string up and down vertically from about 5" to 10" apart. I'm an ok shot but then two of the range masters shot (both of whom are excellent shots) and they had the same problem. Nice groups but strung vertically up and down, no flyers to the right or left. So the windage was fine but the groups were moving up and down vertically. (I should note that it seemed that a few of the new upper's front sight tip was not in a locked position out of the box but rather right in the middle. That was fixed before shooting.)
I put on another new Thompson/Center barrel and the problem was solved.
Anyone ever heard of this problem?
After much back and forth we found out that S&W had purchased Thompson/Center and were in the process of moving Thompson/Center's machinery over to the S&W factory (or so we were told). In order to boost production and fill orders S&W farmed out the barrels and purchased a bunch from Mossberg. The batch of rifles we had came with some Mossberg barrels and some Thompson/Center barrels. I believe the Thompson/Center barrels have a "-X" on the barrel while the Mossberg barrels have a "xX" or something similar. So the barrels that were having problems with are the Mossberg barrels.
So S&W sent us all new Thompson/Center uppers. We went to the range today and changed out the uppers and all of them shot fine, except mine. Mine made ok groups at 100 yards but they seemed to string up and down vertically from about 5" to 10" apart. I'm an ok shot but then two of the range masters shot (both of whom are excellent shots) and they had the same problem. Nice groups but strung vertically up and down, no flyers to the right or left. So the windage was fine but the groups were moving up and down vertically. (I should note that it seemed that a few of the new upper's front sight tip was not in a locked position out of the box but rather right in the middle. That was fixed before shooting.)
I put on another new Thompson/Center barrel and the problem was solved.
Anyone ever heard of this problem?