I have done some conversions:
1) Made a 38 sp insert for a 45/70 Handi Rifle
2) Converted 8mm mausers to 243, 257RAI, 223, 308, 7x57mm, 45acp, 30 Mauser, 300 Win Mag
3) Converted Tokarev pistol from 9x19 to 9x23
4) Converted Star Super B from 9x19 to 9x23
5) Converted 308 Mauser barrel to Tokarev pistol barrel in 7.62x25mm
6) Made 12 gauge insert to shoot 22 long rifle rimfire
7) Converted handi rifle 12 ga barrel to take Rem chokes

Converted two VZ24 actions into one short 6mmBR action and one long 338 Lapua action
9) Converted 91/30 Mosin Nagant to 45/70
10) Converted Win 94 30-30 barrel to screw in 91/30 action with a bushing
11) Converted injection moulded Ramline Sav110 stock to Alluminum V block bedding
12) Converted Arisaka 99 300 Savage to 308 Win.
13) Converted Ruger 10/22 match chamber to Stinger chamber
14) Converted Springfield 30-06 barrel to 7.62x54R on 91/30 action
15) Converted old 12 ga barrels into Rem Choke extenders
16) Others
I have a 1911 barrel here that was relined from 45acp to 7.62x25mm by the Chinese.
Workmanship was not too good.