Bob's thread of yesterday on the "Odd Choke Boring" prompts me to show what can be done to PROPERLY open-up chokes while maintaining their tapered profile as done by Fox, Lefever, Parker and others. Bad vibes when you check an otherwise honest double gun that's supposed to have full tapered chokes and you find that one or both have been opened-up to parallel with an adjustable reamer.
I like to use tight chokes as done per order by the factory but also know that upland guns used for grouse and other quick flushing birds can benefit by reworking overly tight chokes. To do that I’ve had tapered reamers made to nominal Fox taper specs for 12-16-20 that drive from the breech end and are double-piloted with the bore to keep the new choke(s) perfectly centered. The pilots are turned on the lathe to .001" smaller than bore diameter in each tube.
I had the reamers and their tooling made for my own use and occasionally do chokes for good friends. Note that I don't do this work commercially and AM NOT soliciting business. Basically it’s an avocation.
Yesterday I opened the chokes on a VH 12 just bought by a bird hunting friend. As made by Parker the barrels were: RIGHT .026" constriction (Improved Mod) with a 4" long taper out to the muzzle, and LEFT .041" constriction (X-Full) with a 4-1/4" long taper.
The pics will show a tapered reamer in use in each barrel and that finished choke. A blue light was used for visual contrast. You'll see some lint in each choke and the smooth finish as reamed but before final honing/polishing. New chokes are RIGHT .016" constriction (Light Mod) and LEFT .025" constriction (Imp-Mod). Lengths of the choke tapers were not altered and the barrel set lost only 0.2 ounces of steel per my digital scale.
First two pics are the Right barrel, and last two are the Left. Just to show what can be done.

Yeah I know this is heresy to some but to each his own.