Will a G33/40 have the same diameter receiver where the barrel threads into compared to a large ring 98? I was wondering if it is the inside dimensions that are smaller rather than the outside. I guess to further my question, what dimensions are different on the 33/40. Thanks.

The ring diameter & barrel shank are both smaller.

fla3006 is correct.

But, note that on some of the receivers like the 1909 Peruvian, 1903 Turks, and indigenously made Turks, the outside diameter is of standard LR 98 dimension while the threads are of small ring proportion.

From Olson's book.

The barrel shank diameter on a 33/40 is .980 and on a regular 98 its 1.100.

The receiver ring diamter on a 33/40 is 1.295 and on a regular 98 its 1.420

The thickness of the left side receiver wall on a 33/40 is .085 and on a regular 98 its .150.