T grade 1885 Parker
 

I have an 1885 Parker T grade with reverse chokes. No, not switched left to right, but
instead of a constriction, the chokes open up, like a Blunderbuss. They measure as ten gauge chokes, the shotgun is a twelve gauge. Has anyone seen this?

What is the bore diameter and choke constriction?

At the end of the barrel, right .758, left:.754, I have no way of measuring nine inches inside the barrel to obtain barrel inside diameter. I assume it is the 12 gauge standard 729-.730.

The bore is just oversized. This is common. I have seen plenty of 12g guns with near 10g sized bores than still had plenty of choke in them.

To Brians point my Quality T Hammer 12 bore from 1891 has bores that measure .755 and .754 with choke constrictions of .037 and .038.

I will try to borrow a gauge to measure the inside of the barrels, but there is a visible outward flair of the end of the barrels.

Photos?

I own a number of 12 and 10 ga Parkers and every one is a perfect bore size larger. The 12s are 11 gauge and the 10s are 9 ga. The Parker Story discusses and lists the date the factory records say they switched to standard size barrels unless the larger barrels are ordered.

Finally measured bores, 0.750 four inches inside muzzle, 0.750 two inches past chamber, both barrels. .758 and 0.754 at end of barrels (muzzle).

That sounds untouched for a typical bore of that vintage, although they were starting to phase them out. Sounds like someone reamed the chokes out.