I went to the range yesterday as a formality to make sure my go-to deer rifle was still putting them where it is supposed to. I hadn't shot the gun since Feb as it is generally too warm here in the spring/summer to make shooting enjoyable and this particular gun is boringly consistent. The gun is a SS Win Model 70 Classic 270 WSM in a Bansner stock with a VX3 3.5-10x40 CDS scope. Admittedly the gun had been bounced around a bit since its last range session but I used it between Oct and Feb last season to take 8 different animals from 80 to 300+ yards and it always hit exactly where I aimed it.

Yesterday I shot 3 different loads through this rifle that are known MOA or sub-MOA performers. All three produced ugly triangular "patterns" in the 2.5-2.75" range (3 shot groups as any more seemed like a waste). I double checked the mounts and the stock screws as well as the CDS setting etc. The focus ring was slightly loose but everything else checked out. As I was packing up to go home I recalled that I had a 4th ammo type with me that had never shot well in this gun (3" or > groups) so I figured why not. The first 3 shots with this ammo went into a neat cloverleaf. I adjusted the scope to bring the POA to the desired spot and shot another tight group so the scope seems to be fine.

This rifle has never dropped off in accuracy like this from a "dirty" barrel before but is it possible that it reached the tipping point for all 3 types of proven bullet/load? Why did the 140 TSX that had always shot terribly in this gun now decide to shoot .5" groups? Is it possible that some bullets perform this much better due to a dirty barrel? I would estimate that the gun only had 15 rounds down the tube since its last cleaning before the range sessios and it has never been finicky before.

I cleaned the gun last night and it didn't appear to be any more dirty than normal. There wasn't noticeable copper fouling and the carbon etc. cleaned right up with some wipeout. My plan going forward is to shoot it again to see if the clean barrel produces the normal results w? Accubonds. If not I'll get it good and dirty and see if the TSX's will shoot again.

Am I missing something here or have you guys seen similar in your guns? I was suspecting dirty barrel or possible crown issue until the TSX's decided to go .5 MOA - now I'm just kind of stumped.