I'm not 100% sure the 17hmr barrel is 1137, it may very well be 4140 since Green Mountain does make 4140 .17 cal barrels and H&R has sourced barrels from them before. Larry (trotterlg) called about the 17 rimfire barrels and was told they're the same material as the centerfire barrels......but that wouldn't be the first time we've been misinformed by CS, and also possibly why he never got it to shoot good if it is 1137. I got my info from a very reliable but anonymous source, so I have no doubt it's accurate, just maybe not all inclusive.
Tim