Second the above... the knurled metal is not "added metal". It's displaced from someplace else. For every bearing surface "added" by knurling, another is removed... so the end result would be radial bearing surfaces but not on 100% of the designed bearing surface. There's always going to be a little air in there, so to speak.
With that said... similar technique has worked out OK in other applications. This is a fairly critical one though. Normally I would suggest "weld a ring and machine to diameter" but with heat treatment and all... not in this case. With that said, if you have someone who is very good with a TIG torch you might have them put 4 small dots of weld at 90 degree points at the most forward and most rearward areas where it matches the trunion, and then lathe-cut to a very slightly oversize dimension, and then press to fit. They need to "just" make the spots... with perfect control and lowest possible heat.
You "might" consider trying one with knurling backed up with judicious application of a high temperature epoxy as you make the press fit. My guess is that it would be OK for a very long while... but only a test will tell for sure.
Personally, I would try the knurl and epoxy, not a lot to lose in any event.
Have you thought about cross-pinning in addition to knurling and press fitting? Mark a hole on on the trunion so as to have a 3/32-1/8 or so cross pin be placed so that half of it's diameter will be in the barrel (IE: just a notch in the BBL will result), press fit, drill the hole, pin, and grind flush? That'll never move. Larger diameter pins will be easier to mark for and place.
Just a few ideas from an old hobby-smith.
Last edited by Willie Sutton; May 21, 2012 at 11:59 AM.