Enfield No 5, stuck screw advice?

[Patrick Chadwick]

Catch22, as in your area 4BA material is not going to be available on every street corner, you might find it easier to obtain a UNF #6-40 screw! Although the 4BA has a 38.5 tpi thread, a #6-40 should be quite feasible over the short thread length that is being used. Oil it well and ease it in.