I have had this 7mm for 10 yrs and it has always been a tack driver out to 300yds. This spring when i brought it to the range I noticed it wan't grouping like it used to but I just chalked it up as i havent shot it in a while. Over the last week I have shot about 30rds though it and cannot get it on. I have taken everything apart, lock tighted it and put it back together. yesterday I went back out and sighted it in at 50yds (had it dead center) took it out to 100yds and it was all over the place, brought it back to 50yd and it was all over the place, during this time the gun never left the vice. at this point I have no idea what it could be but is sounds like somthing is getting jarred loose yet everything I can see is tight.