The purpose of the keels was to align the ribs in relation to the barrel tubes before soldering. The one I have/had is straight sided and about 1 1/4" long or so.





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I am sure they all started out similar size. They would be inserted inbetween the tubes on top and bottom as far as they would go. And cut off after soldering was done. They are there for filler material only. Nothing more. They serve little purpose by way of rib alignment. The tubes touch and the rib sits on top of the two tubes.

Farther back, the tubes are spaced out with flat pieces of shim material, maybe 1” long. Usually there are usually 3 places that these shims are placed. Sometimes it may be one large shim. And other times multiple shims. They end up all being soldered together through the process.

I will see if I can grab a photo of some disassembled barrels showing these spacing shims.

Some photos of the spacer shims on the inside of Parker barrels.

Attachment 86078

Attachment 86079

Attachment 86080

Keels offered no structural integrity. They were there to take up space, because solder (Sn and Pb) is much heavier than steel, and if they just filled the whole gap between barrels and ribs with solder, the barrels would be too heavy at the muzzle.

Wonder if one could just get a cut nail and then file off one side and shorten and bingo, you have a shim.