I do think it was me who mentioned using solder paste in rib repair in a posting way back in the past. Though it was only for repairing very short runs and the odd place where the rib had parted company with the barrels. It works very well if you put it in a hypodermic syringe and use a large bore dosing needle forcing it under the rib with the careful use of a lead pencil giving minimum cleaning up of the end result. Though to use paste for a complete relay besides the extremely high cost for solder paste, it has difficulty in bridging very small gaps and if you heat the paste you will find that the solder content is minimal. The largest user of paste is the Electronics industry with their preferred mix of 60% Tin 40% Lead so not having the same strength and a lower melting point as 60% Lead 40% Tin though all solders are changing fast to Lead free.
Hollands promotional video, can I give you my thoughts about it? Bespoke London gunmakers lean heavily on the use of the tradition very chance they get!!! Well they do have to justify there high prices don't they? That sequence of soldering ribs using a 2 inch Propane burner nozzle and lumps of Rosin for flux with flames looking like the entrance to Hell plays to the past and the gallery very well. Though I don't think they do it all the time, my reasoning for this is I have done this very thing once and it was a lesson and a half because it took hours and hours to clean the barrels up because you have no control of the solder and flux flow. This is possibly allowed for in the cost for a new set of barrels for a new high price gun but for a repair and normal manufacture I don't think so! To relay a rib I use as small a flame as I can get away with working a small length at a time using modern Rosin based flux and 14 gauge plumbers solder hammered flat to get into the small gap between the rib and the barrel plus a lead pencil. This method I found does minimal damage to finishes and if you are really lucky you may only need to do some touching up rather than a full refinish job.
