Next, switch to threading steel, just common (1018) is OK to start with. The stuff you can buy at the hardware or Fastenal. Get some 1" in diameter. Move to 16T.P.I. or fewer. The carriage will move at a faster rate toward the shoulder with fewer T.P.I. , and you need to get used to that. With a piece of 1" bar you can again go to Fastenal or the hardware and buy a 7/8" fine threaded nut. Make your cut threads fit the nut (7/8" will have you threading to a shoulder, 3/4" fine would be OK, too). Thread gages are kinda' worthless for gunsmith work as any threads you will deal with should be 'custom fit',, not too tight and not too loose. The only threads I 'work' as standard are guard screws. I might take a hand tap and chase those if I need to. But barrel tenons and threaded muzzles for brakes are a custom fit, fit to the receiver or brake that will be used. Also, when you have your thread fitting the way you want it, it hurts nothing to take a clean mill bastard file and 'break the crest' on your cut threads. Again, not too much, just a little. Practice, practice, practice,,,,,,,,,, until you are satisfied and confident. Then you can move on to "picking-up" an existing thread. I set my cross slide handle at the 9 o'clock position. That way it is a straight push down at the end of the thread to back the tool out, it's a natural movement. Anywhere between 9 and 11 o'clock, wherever you are comfortable.
Sue to my machine sitting for a long time before I got it, I can really only thread limited pitches. I went with 24tpi. This is my second attempt. The first attempt will be buried without seeing the light of day...
