Don't you mean 42" chest?

I just measured around my 125 lb, 5' 2" wife's shoulders and it's about 44". Mine are another 10 inches or so and it's even wider around my body where my elbows stick out. I'm muscular, 5' 8" and weigh about 180 lbs.

I too have problems with sleeping bags being too tight around the shoulders and elbows. Feathered Friends Swallow, for example, is too tight. I now have a Montbell stretch bag that runs about 2 lbs and is good to about 20 degrees F. I've been real happy with it.