Makarov Barrel replacement

[Roadkill]

Evening, I need to replace barrel in a Makarov, anything secial I need to know? Also, I replaced the mainspring in the Colt 1905 .32 long police positive without any problem, gun works great. Am having a problem with a spring in a Webley .45, is the one that raises the catch that locks the cylinder. Can't get it work right.

thanks

rgg