You're right-on, Alex, My buddy bought a PacNor 3 groove barrel, in .172 cal. & I chambered it by hand, then put it on his .375H&H #1. It took several orders to get the right extractor as the supply company is in Quebec- something was lost in the translation and they had a diffuclt time sending a Hornet Extractor for a serial # that was for a .375. The rifle shows no stringing or double grouping, and as per PacNor's norm shoots tiny 5 shot groups in the 3/8" range and busts gophers to almost 500 yards - acid test just last month. Brad's happy with his #1 and now wants to re-barrel his Martini .17Ah to a PacNor. Mine is on order right now and is expected any day now.