Underlug and sight fit in dovetails

[frogwalking]

I have built a number of guns in my life.  It escapes me exactly why this possibility has never occurred to me before.  In ideal circumstances (in my mind) the tennon or sight must be driven into the dovetail with a reasonable amount of force.  (It seems that many of the tennons and sights I buy from TOW are 0.05 inch thick.  Unless the barrel is quite thin, I just cut the dovetail to match.)  I normally use a brass drift and a small ball peen hammer.  I suppose my engraving hammer would work, but is kinda light for the job.  In thinking of the things that can turn a good, accurate barrel into a toad, it seems to me that a really tight tennon could do the job;  minutely bending the barrel by wedging it too hard.  Has anyone experienced this?  Is there a simple way to determine how tight is too tight?

[D. Taylor Sapergia]

I have not.  When I drive a sight/under-lug into a dovetail, and some are as deep as .062" (1/16"), the metal to metal fit is very tight, but no metal is being upset in this process.  The metal of the male part is more likely to collapse that the barrel stretch or bend.  And the base of a front sight is copper or brass normally, and you can use brass for under-lugs too and avoid any possibility of warping the barrel.  But warping has never been a problem.  The rear sight has metal raised with a cold chisel, and is used to stake down the sight.