I have the baby frame Winchester Model 23 Classics in .410-bore and 28-gauge, and the firing pin centers are 15/16 inch on both. The 28-gauge tubes touch at the muzzle and the .410-bore tubes have that horrendous gap. My .410-bore Crescent is on a frame with 15/16 inch firing pin centers and the tubes touch at the muzzle. My Ithaca NID .410-bore has firing pins 29/32 inch center-to-center, the same as my two 28-gauge NIDs. The tubes of both the .410-bore and the 28-gauges touch at the muzzle. The barrels are 26-inch on all six of the above guns.
