(which appears to be more common lately )
I'm a\saying solder on a riser platform, solder the breach to that, but modify a slip in barrel held by sets crews (sealing it is still a design issue).
Riser plate, and necessary rework of the front barrel band, will allow a shroud of say carbon fibre or thin walled aluminum.
Barrel,as you say is likely to be steel, and will not be soldered.
But a soldered on "band", say 1/2 down, with an ID of what the CF shroud's OD is a good idea.
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