I haven't tried this on sights before but could Gimp do it? Like just downloading the sight and then adjusting it with Gimp to be larger?
yes it can be done........yes I have made for my personal use, 3 enlarged gunbore sights for the F4U plane types I fly.....
trial & error / trial & error........ make sure you keep the gunsight.bmp file in the same resolution & same Bit state...... also if you are using the types that have a glow like feature.make sure you have both your alpha and regular .bmp files the same and accurately overlayed......
I have used MSpaint, photoshop, and paint.net to make mine.....
edit: for starters just make u a backup copy of the default gunsight and then enlarge/redraw but BE SURE TO NOT LOSE OR MOVE THE "CENTER" dot..... if you lose or move the center dot, then your whole convergence and aiming will be off kilt...