Another Frame Size Question

[Jay Oliver]

I was hoping someone could help me figure out the sizing of some orphan barrels I recently bought. They are 26” Twist 16 gauge “0” frame barrels serial# 74008 and are in nice shape. They are smaller narrower than the 2 “0” frame 20 gauge Parkers I have, serial numbers 114,xxx and 120,xxx.

Since these 16 gauge barrels are earlier, did earlier hammerless Parkers change the size of the “0” Frame over time? I posted some comparisons of these barrels and my 20 gauge GH barrels(it was hard to get good pictures holding the calipers and the camera, but I did my best). The narrower barrels are the 16 gauge twist barrels.

Would these barrels fit on an earlier gun?

Thank you,
Jay