washandwear you have got it backwards, he wants a extremely tight choke, not a open choke.
A normal Perazzi has a bore of .720 to .730. If he wants a .640 - .650 bored choke tube then you would have a restriction of approx. .080 !!! My Kreighoff K-80 TS has been custom choked by Tom Wilkinson (not screw in chokes) is .034.
Is this going to be a card shooter or turkey gun? I have never known anyone to use a choke this tight for trapshooting. You might call Tom and ask him if he would make you a custom screw in choke, he does make custom screw in chokes for clay target guns. Costs would be pricey, so be prepared. Tom's Phone # is 919-603-0167.
Clearview chokes will make you any tube you want.. He'll discuss the total profiles with you.. and try to produce exactly what you want.. At .675 on a .729 bore.. The pattern with 5/8oz of shot at 1450fps was fantastic at 60 yards.. It was not that large.. but prduced target crushing patterns.. If you did your part.. the results were impressive. All Good..Mike
There is a distinct pattern for each and every tube..and the results you get.. you'll reach a point of no return.. then negative returns.. Speed,shot size,wad combinations.. all play a distinct role in the quest for the tighest,most dense pattern at long ranges. Might I suggest dropping down in .005 steps until you reach the pattern shifting the other way.. over the years I've played with many of them.. If any of you know Tom Casey..I spent alot of time around him while he was making the "Tom Choke".. and he was my mentor of light payload..tight and tighter chokes.. Remember.. many of the Italian live bird guns were choked .040/.050 on a .724 bore.. So.. really a .050 choke is nothing new..and many approached .065 on a proper bore gauge.. Having said all this.. the profile of the #10 Wright choke has proved excellent for nice patterns at extended ranges..BUT.. upon request the Clearview choke people cut me a humdinger of a choke that measured .039 and was devastating at extreme ranges because of its extremely "HOT" inkball everytime design.. There is more to choketubes than just numbers..and I have found different makers of tubes often have different charastics.. In this quest.. my first call is Clearview.. Ballistic Specialties would be second on my list.. One of them can help you.. Remember.. you will be limited the #8 or finer shot with an over .060 constriction unless you have a light payload..
Hey Buddy..Things are so bad in New Orleans.. the hookers are still virgins.. I will not be attending the Southern Grand.. but Dan and I spoke today.. and I'll be working with He and Giacomo for the entire "Grand" this year.. Sooooooo.. if you're up that way..you know where to find me.. Look forward to the drink.. but more seeing a good friend.. As always..All Good.. Mike
I notified Marcello in Italy and he know the folks who make the Perazzi chokes.
He told me this morning, that they refused to make a 12 gauge choke with a 20 gauge restriction. He said the Perazzi choke maker would not make it because of the possibility of too much pressures. They thought that the restriction request was off their charts for safety.