I have the very rifle you speak of. M70 sporter in 25-06. Bought it less than a year ago. Right out of the box, it was misfiring about half the time. Thought I had bad primers in my handloads, so tried a box of hornady factory ammo. Same thing. Took it to my gunsmith, and a hundred and some bucks later, it was fixed. Bad firing pin and spring. Seriously? From a brand new rifle? Wow. So I got it back. Pillar bedded the stock. Glass bedded the action, and replaced the trigger spring. Should be good. Or not. Accuracy absolutely sucked. Used half a dozen different bullets. About the same with powder. Used 100 grain, 115 grain, 117 grain, and 120 grain. Accuracy hovered around 1 1/4". Sometimes a little better, often times worse. Tried solid copper hammers as well. Every now and then, it would throw a 3/4" group, and I was all excited, and the next day, with the same ammo, it'd be double, or even triple that. Finally, I just stuck it in a corner until this last weekend. Decided I was going to clean the holy bejesus out of it with some really potent copper solvent. So i used montana extreme copper killer, and scrubbed the bore and let it sit. Ran a bronze brush down it maybe a dozen times, followed by about 20 patches. Then I did the same process over again a 2nd time, then a 3rd time. Spent a good 4-5 hours cleaning it. After that, I loaded up 3 rounds of 120 grain speer hot-cors up, ahead of 50 grains of Norma MRP. 1 1/2" group. Loaded up 3 more with 51 grains. 1" group. 3 more at 52 grains. 1/2" group. 3 more at 52 resulted in 1/4" group. Shot @ 200 yards yesterday with 51.2 grains of MRP. 1st group @ 1 1/4" and next group @ 1 7/8". Avg velocity was 3017 with ES of 6 and change and SD of 2 and change. I can't explain any of what happened with any certitude, but I'm guessing that between getting a couple hundred rounds down the barrel, and that 4 hour cleaning job, that the barrel finally settled in. I could be wrong, but that's all I have is a guess.