Do you have any information regarding the tula choke, ie. where & who developed this design. I have a Perazzi which I believe has this configuration.
I don’t know how absolutely right I am, but I can give you the story as I heard it. In the ’50s the US team was shooting an International Skeet match in Scandinavia. At that time it was mostly Air Force guys and some of them used the Browning A5 with a Cutts compensator. At the end of the match, which one of the US guys with an A5 won, a Russian came over and offered to buy the A5. His price was so good that the service man couldn’t turn it down. An hour later the Russian came back and gave the American back the gun, less the front 10″ of the barrel, including the Cutts. He said he didn’t need the rest.
Some time thereafter, the Russians produced jug chokes on their Baikal MU-6 and MU-8 International Skeet guns. Yuri Tsuranov and Evgenie Petrov used them to dominate IntSk during the ’70s. Perazzi and Krieghoff were quick to follow with their versions of the jug choke. The name “Tula” choke comes from the Russian arsenal of that name where it was thought that the development work was done.
The theory behind the Tula/jug/Cutts is all the same. Shot goes down the barrel bore until it enters the plenum chamber. The pellets on the outside which have been scrubbed and damaged by the walls of the bore start to separate out in this plenum chamber (remember, this was built for fiber wads). The shot column then enters a choke (larger than bore diameter, but smaller than plenum chamber diameter, and the scrubbed and damaged shot is vectored back into the shot column.
The jug choke also adds some shot stringing to the equation by slightly retarding the outer pellets. Due to the close range and high pellet count of a 32 gram skeet load of #9s (the current ISU load is 24 grams) a bit of stringing on the crossing targets works to your advantage.
What surprised me about the jug choke on my Perazzi Comp I was that it performed better with a plastic wad shell than it did with a fiber wad one. I had the special Federal T-123 fiberwad master blaster IntSk loads and tested them against the standard Federal paper 3 dram skeet load. The gun gave me bigger and better patterns with the plastic wad. Perhaps the jug choke acted to retard the wad slightly and separate it from the column in some way. My Perazzis had little gill slits cut by the factory in the choke area. They were supposed to reduce recoil, but didn’t do any more good than porting does today. Perhaps they helped vent pressure and retard the wad.
I also had some Krieghoffs- one with a jug choke and one with standard Krieghoff skeet chokes. The barrel with the standard chokes outperformed the jug choke barrel with every shell I tried in it. Other IntSk shooters have been very pleased with the jug chokes in the K-80, so perhaps my experiments had different variables- or they didn’t have a second standard choke barrel to test against.
Bottom line to all of this is that you absolutely have to go out and pattern with a bunch of different shells to find out what your gun likes best. No other way. You can read all the junk you want from know it alls like me and it won’t do you any good. You have to do the work or else take things on blind faith.
There it is, or at least my version of it. If you get a better story, I’d love to hear it.
The Technoid at <www.ShotgunReport.com>
(Often in error, never in doubt.)