I'll take a swag - you may well be over-cleaning the barrel. Did you recently change your cleaning regimine or choice of solvents?
I have seen several threads of late involving this question. I know that when I aggresively clean my rifles, it takes at least 10-25 rounds to get them back to shooting farily tight groups. By accident, I found out that at least one of my rifles likes to be really dirty.
I'm currently shooting a 7WSM for F-Class at 600 yards and 1K monthly at my home range. I was in a hurry to do some family things following the last two matches in August, and completely forgot to clean the rifle. I remembered this fact, only when I was up on the line in September. That day I shot the two best relay scores of 2008. It turns out my rifle shoots like crazy with over 200 rounds down the pipe and no cleaning. Who knew? I was paranoid that I would have a serious carbon ring problem, but that was not the case. Needless to say, I don't let it get nearly that dirty between cleanings, but I am not nearly as anal about cleaning as I used to be, and I let it go longer then I normally did before.
JeffVN
