What he said
Grind one edge of the triangular file flat
Buy a good quality file and keep it just for doing dovetails
Use a candle or kerosene lantern to smoke some soot on the part to fit and look at the cleaned off parts to see where to file a little more
Always insert parts from right to left
And remove left to right
Mark the front of the part so you don't fit it wrong way around and file the wrong places
Always use a brass drift and direct hammer
Smoke and fit dozens of times of needs be
Better than rushing past the best fit
AND NEVER PUT THE BARREL OR ACTION IN A VICE WITHOUT JAW PROTECTORS AND A PIECE OF LEATHER !
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