Hi, I have done a few of these, !
It needs the barrel to be taken off & cleaned up & Re-soldered ,
Here is a Sheridan (converted to PCP because the inlet valve was damaged ) With a .22 calibre " Setra " Barrel.
It is of course capable of outputs Sheridan never dreamed of ! Its .22 & 2000Psi & Makes !!! Better not say as I live in the UK, ?
Its regulated to 12 Fpe by the hammer spring.
Back to the barrel & Solder !
Solder is generally 60% lead & 40% Tin, Lead melts at 327C & Tin at 232c,
The reason this is important is that Solder is an amalgam of the 2, Melting temp is ( Well you work it out ) Ha ha,
The valve body in the Sheridan is soldered in,Its crimped to hold it but Care has to be taken not to melt this & let the solder run in to the Inlet valve threads ?
I do this by standing the action in a " Particular " position & using Tin ( Which has a lower melting temperature than solder at 232C ) Hence less heat input.
Hope this helps, Ged.