had about 600 rounds through my Green Mountain barrel. followed break in procedures. Shot everything from bulk to tenex.....wasnt any better than the factory barrel, no granted the factory barrel shot pretty well. It'll be interesting to see how the ER shaw does with velocity and accuracy. I got the 20" in hopes of keeping things slow velocity wise. id be happy with low sd's and factory barrel accuracy honestly. ive dont a lot of work to this rifle. I enjoy polishing turds although I may just jump on the voodoo wagon sooner than later.