Funny, I'm building a standard silhouette rifle on a Rem 580 action now too. I threaded mine to 11/16 - 24, but same idea. I'll probably torque it to about 30 ft/lbs or so. It doesn't have to be extremely tight, and torque isn't going to be real critical either. Just snug it up enough to not come loose. I have a couple of questions for you though. You said you're using shims to get the extractor cuts in the right place. This implies you cut the slots before you cut the shank to length and chambered it? How are you going to control headspace this way? The other question is how are you going to eject a fired case? They're quite a bit longer than the ejection port. I thought about doing one of these in hornet, and I think it'll almost work if the bolt stop notch on the bolt was cut as far forward as possible, and the ejection port was milled back as far as possible, but it would still be really tight. I decided a .22 squirrel would be a better choice, or something based on the 25 or 32 ACP case. Tell us how you did it, I have a couple more of these actions I'd like to build a centerfire with someday. BTW, I figured out how to make the trigger adjustable. They are truly superb set up like this, and way superior to the aftermarket triggers available.
