What do you call a choke that is in reverse? I was measuring the bores of a Needham I just purchased and one barrel measures .722 at 9" and .733 at the muzzle. Is that 'Extra Open'?. The other barrel measures .732 at 9'" and .731 at the muzzle. Taking it out the weekend to shoot some clays unfortunately where I'm going I do not have a pattern board.

On another note I just purchased a new to me Browning Citori with Briley screw in steel chokes. Came with 2 Improved Modified and one measures .710 and the other .715. Shouldn't they measure the same or do Briley chokes have that much tolerance? (First gun with screw in chokes I've had to play with)

I think that is called a blunderbuss.

There are several choke profiles shown here
https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=630097

Also referred to as a "Bell choke"
https://sageandbraker.com/blogs/news/shotgun-chokes

Some call the set up when the R barrel choke is tighter than the L as "reverse chokes". Often for incoming driven game or waterfowl, but John Olin thought it was the best choice for the outgoing targets on the skeet field.

In the realm of screw-in choke tubes the range is usually from negative .005" (five thousandths more open than the bore diameter) to XXX Full (somewhere around .055"), maybe more according to the manufacturer. IMO. Based on my patterning and usage, a "negative" patterns no more open than a CYL. JMHO.

Took the Needham out this weekend and shot some traps I never hit one with the reverse choked barrel. The cylinder barrel shot okay

I have a Rottweil 72 Olympia with TULA chokes, they are wonderful

https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=551756

Mike