Using a rifle barrel on an SB1 frame isn't recommended, H&R just started offering the 357 and 44 mags on SB1 frames this, but they have small firing pins and the surrounding hole, they also won't fit any other barrels to those frames except shotgun barrels. They won't fit ANY rifle barrels to SB1 frames except the 45-410 barrel.
Please read the FAQs info on frame differences, there a substantial difference in frame strength, I agree with Longtom's advice, since you have an SB2 frame, use it for the 44mag barrel and be safe.
Tim