I'm working on my son's first rifle now and I'm using a .50 cal B wieght 38" colerain barrel. It wieghs 3.7 lbs. The rifle I just finished has a 42" b wieght .45 colerain barrel, it's still a bit heavy for my wife. That barrel wieghs in at 5 lbs. One thing to remember a 42" b wieght profile is different that that of a 38" or 44" barrel.
Here are some wieght comparisons.
38" B wieght barrel .45 cal is 4.2 lbs, .50 is 3.7lbs
42" B wieght barrel .45 cal is 5.0 lbs, .50 is 4.5 lbs
44" B wieght barrel .45 cal is 4.72lbs, .50 is 4.2 lbs.
I have handled guns with b wieght barrels and was amazed how much difference a half pound makes. I was also a bit suprised that due to the profile, the 44" barrel is lighter than the 42". If I could ever convince my wife to get into shooting with us I'd build her a gun using a 38" b wieght barrel. Those that prefer heavier guns will probably tell you different.