Rifle Scopes Diagnosing scope issues?

[moosemeat]

So i have a issue i am chasing as of today. I went to a local club BR match with my FN SPR 308 and a load that has shot well in the past. I have won this match before and won the money shoot after with this rifle and load. My BEST group across 30 rounds was .97" and was the first group after sighters.
The groups got consistently worse and the last was 2"+. My ground hog was horrible. My clicks feel fine. But I noticed every time the shooter next to me fired my reticle would move off the target. Without me moving the rifle on the bags it would return to zero.
After the match I had 2nd place shoot my rifle(he shot a .237 group, so hes good). His 1st 2 shots made one hole. 3rd shot went 1.5" left. 4th 1 hole. 5th 1.5" to 11 oclock.
After going home i called my buddy with a range and went over there. I checked every screw and remounted the scope after really cleaning the rifle.Then I seasoned the barrel with some 147 mil surp. He had a box of fgmm thats a known shooter in this rifle and that shit was a 3"+ group. Rounds 1 and 2 same holed but the others had a random pattern.
Sound like a scope issue? The match before this, a 300 yard prone this same rifle and scope shot a 298 out of 300. I dont know what else woukd cause a rapid deterioration of accuracy except a shot out barrel and this barrel has 2985 rounds on it and is chrome lined so it should last.

 

[Birddog6424]

Step one is always a ring and scope swap to narrow it down to the rifle or sighting system. If you have a screw on scope base, check the screws while swapping.

If you drop a different optic in different rings on the rifle and it shoots. You know its the scope or the rings. Or vice versa.

 

[moosemeat]

I dont have a second optic of power high enough to test on the rifle. My other optic is a 1-4.5 that I really dont think would evaluate the rifle. I have asked my buddy if we can swap scopes from one of his rifles to this one.
I have taken the rings off and checked the torque on everything. I have it narrowed down to the barrel has taken a dump or the scope. The scope has a lifetime warrenty and I can send it back.

 

[Precision Underground]

I dont have a second optic of power high enough to test on the rifle. My other optic is a 1-4.5 that I really dont think would evaluate the rifle. I have asked my buddy if we can swap scopes from one of his rifles to this one.
I have taken the rings off and checked the torque on everything. I have it narrowed down to the barrel has taken a dump or the scope. The scope has a lifetime warrenty and I can send it back.

Put the 4.5 on it and shoot it at 50 yards. You should be able to do much better than 2 moa with that so it will tell you if something changed. You don’t have to shoot a .25moa group you just need to see if it shrinks. Shoot it at 50 with the current scope first then swap.