Hello, 

I've recently bought a Sharps-Borchardt in 40 2 1/2 cal , sporterized by J.P. Lower , Denver, as stamped on the barrel. the barrel was also stamped with "cal 40 2 1/2". I've purchased a box of ammo Sharps 40 straight shell, paper patched bullet, and 2 1/2 lenght. The bullet diameter , on the patch, is .398.
The problem is that the bore , at the muzzle , is MUCH greater than this; I can easily slug a .45 bullet  through the barrel.
So my question is : is it possible that the stamp .40 cal on the barrel is wrong ? How could I know the right munition for that gun? I suppose that the first thing is to take the exact dimensions of the chamber , right? This problem worries me , because J. Lower was a reputated gunmaker , so what ? Thanks for help 

Probably been rebored as suggested already. No way a .45 caliber bullet should be able to be pushed through a .40 caliber bore. I own a Sharps .40 X 2.5" Midrange and I could not even 
get a .45 Caliber bullet all the way into the chamber. Reboring was a common practice back then and is fast becoming some what common today. HTH Regards, FITZ.

aldea6 Please check your PM.

Aldea6,

Does your Borchardt have a saddle ring on the left hand side of the action or signs that indicates one was fitted?

Harry