My dad and I have been working on his 7MM for quite a while now. Typically we can get a gun sighted in within 2 trips to the range at 100 yards just for a base line. Yet this dang thing just wont stay with a grouping. It has a Boss and a Mussel break setup that is one piece, and we sent it to the factory to make sure it was proper but they sent it back with a decent group (1-2in of 3 shots) we shoot 3 shots per grouping due to barrel over heating but we consistently have 1 "stray" that puts in off the group. We have a Burris Posi-Lock scope on it and we are guessing that is the probable cause. As for ammunition, we use Remmington Express CORE-LOKT because the factory suggested us. Its an amazing looking gun and she doesn't kick more than my VTR but we are considering of getting rid of it because of how much money invested and no return for the money. Any help would be nice.

I like the BAR. You should be able to get it to shoot well especially with the BOSS.

Put a different scope on it; one from another of your rifles that you know shoots well. Check all of the usual things; screws on bases, rings, stock. Go to YouTube and search for the "how to tune the BOSS" video.

It will work

We have had it "tuned" from the factory. We are using 150gr bullets with it, also as the factory suggested. I believe we are looking at a new scope... most likely a Nikon Monarch series. But is there any other way to figure out if its the rifle not the scope? We have viced it and still gotten the same results.

I've never had an issue with my original BAR in .300wm, but have had a problem x2 with a Burris scope. Change the scope.

Well, looks like I'll be going Nikon haha just gotta put some money away now.

Make sure that the forearm screw is tight...
I've seen them shoot crazy because of this.

I have a beautiful burl walnut Browning Bar in .338 Win mag and it shoots under 3/4-MOA with Federal ammo. The wife had a Bar in a .270 Win but she thought it was a bit heavy for her. However, it still would shoot 3 shots into less than the size of a dime time after time at 100 yards and Federal ammo once again.

mf24
I just looked over the manual for the BAR and the gas system under the forearm is similar to my Rem 7400. I have the same problem you have frist three shots into a very nice 1-1.25" groupd at 100 yards! Then shot 4 an 5 open the group up to 3". After removing all the contact points from the barrel/forearm it was still happening. Only thing I can figure it's heat sink into the action parts tweaking the last two shots! Now I can live with 3 accurate shots cause if anything I shoot needs more then 3 good kill shots out of an '06 I'm in trouble!