"Lyman barrels are 15/16" across the flats, which is .9375. If it's bored out to .615, the barrel walls will be .16125."

I suppose I should have done the math first... It didn't sound that bad when I considered it.

Not only would it be hard to find someone willing to bore it to that, it would be hard to find someone willing to fire it with such thin walls! Since you so kindly pointed out that I could be holding on to a hand grenade I don't think I'd want to use it much!

26 ga (.564") sounds much better to me! You just never know if you may accidentally double charge your load! Yikes!

Or maybe starting with a .50 cal to bore to a 28 ga (.550") so as to be able to use (un)common 28 ga reloading materials.