I just figured out my next build after doing some measurements.
My wife's old .45 CVA Mnt Rifle Barrel that I shortened to 30 inches many years ago (20+ years anyway) - (and this barrel is at least over 40 years old, which I think it's a Douglas) - well, I measured the Lands and Grooves and I came up with .460 Lands / .445 Grooves. Now there's always some room for error - but these measurements were taken from the piece I cut off from the rear of the barrel (a long time ago) and re'breached it with a new plug and added a drum ignition.
So,,, since I bought a Lyman Flintlock "lock" from RobD some time back - its new home will be used for this barrel after I convert it to flint ignition, and make a stock for it. I'm on the ropes of either a full stock - or just maintaining the half stock configuration it's in now. Either way, I'll pin the barrel on rather then go a wedge key. (I like pinning over wedge keys any'day - and that's just me...)
My reasoning for all this is two fold... My wife doesn't shoot this rifle (in fact no one does) and I have already used its Siler "cap" lock years ago on another build - so now it will become a short barreled flintlock... (which I'll give to my grandson as he'll soon be growing out of his "kids" rifle, (the one I built a'long time ago for my son).
I have always like this barrel... The lands and grooves should be good for a .012 thru .018 patch & .433 ball, that's within this combination that can be loaded without a short starter. (At least that's what the math is telling me).
If the weather permits this winter for me to be in my workshop, I'll probably get a start on this project - if not, well I'll be looking at Spring 2020...