I have a cut down S&W Triple Lock that was converted to a carry gun with 4" barrel and target sights some 50+ years ago. It shoots poorly, in terms of accuracy. I have acquired a .455 TL barrel of WWI vintage that begs to be on active duty again. I want a 45Colt ! My question is this, how practical would it be to bore out the 44 S&W special cylinder to 45 Colt. What issues must be addressed to make this old warhorse a practical shooter. Is there much of a delta from the 44spl rim vs the 45 colt rim for head space. Is there sufficient metal in the 44 spl cylinder to ream it out to 45? Will there be timing issues? Your expert comments are much appreciated.

I don't think it would be a problem at all. The 44 and 45 have the same case head thickness and for that matter the same diameter. If the 44 special cylinder is presently fitted to the gun, nothing about timing should change. The 44 special cylinders are the same diameter as the 455 cylinders and lots of those (including one I have) have been reamed to 45 colt. Should work fine.
Fitting the barrel correctly should be the only problem. If it needed set back a turn to time and get correct B/C gap, fitting the center cam where it passes through shroud, and adjusting the extractor locking mechanism would take some time and skill. Could go right together and might not.

Good luck.

Should be a fairly straight forward changeover. Nothing difficult or out of the ordinary for this one.

Can anyone recommend a gunsmith shop that can bore the cylinder to 45 Colt. Don't have anyone close by that does that type work.