Bill,
I do have bore diameters and gave them in the range I provided. However, I don't specifically recall offhand what the M42 was in bore size, just the constriction from several years ago. I'm not at home and frankly, I'm going home from work soon and pack up for a dove hunt trip. So, it'll have to keep.

I have dial bore gauges, some gauge pins, inside dial calipers, inside spring calipers, hole mic's, and small hole gauges.