I shoot a Rottweil Olympia ’72 skeet gun, mainly IntSk but also some English skeet. The gun is actually made by Gamba in Spain. It has fixed “TULA” chokes that open out for the last couple of inches of the barrel to a diameter about the same as the chamber. I am told that the purpose is to increase shot string length rather than pattern diameter. Do you know of any research into this and whether plastic or felt wads make any difference to the effect.
I may be able to be of some help here. I am familiar with the Rottweil and have spent quite a bit of time fooling around with “Tula” chokes.
You are quite right in that, in spite of the German name, your Rottweil Olympia was actually made by Gamba, but in Italy not Spain. The gun was to commemorate Connie Wernheir’s International Skeet Olympic Gold Medal in the 1972 Munich Olympics. Conrad was a great promoter and obviously quite a shot.
The history of the Tula choke is also very interesting. In the early ’50s the US Air Force skeet team was dominant in International events (sic transit gloria mundi). They used mostly Browning A-5s with Cutts compensators at the time. This set up was quite common in the US. The story goes that after they had won a major shoot somewhere in Scandinavia, the Russian coach came up to one of the members and asked to buy his A-5. The offered price was so high that the American could not refuse. An hour or so later the Russian returned and handed the gun back to him- less the front 18″ of the barrel. All he had wanted was that Cutts. Shortly thereafter the Russians came out with the “Tula” jug choke, named after their main arsenal at Tula. They employed it on their Baikal MU-6 and MU-8 Merkel copy O/Us. Yuri Tsuranov went on to set the world record in the 60s or early 70s with that gun. I believe he was the first to ever get 200×200 in a major shoot. The original Perazzi Comp I IntSk gun and the K-80 IntSk guns also used a form of jug choke. The ill fated Smith and Wesson semi-auto imported into the US from Howa Mfg in Japan in the mid and late 70s also had a jug choke.
Just what do these chokes do? Here was the theory, remembering that it all started with the Cutts compensator. Using fiber wads, the design was that the shot and wad would travel down the barrel and enter the plenum chamber (or “jug”) where the damaged shot scrubbed on the barrel walls would start to separate and veer off to the sides. The rush of a gas around the fiber wadding would slightly retard the wad and begin its separation from the shot mass. The Cutts, the Perazzi Comp I and the Howa designed S&W 1000 also had vents in the plenum chamber to assist in venting gasses and (Cutts) reduce recoil. With the wad now slightly retarded and the barrel scrubbed shot beginning to “make a break for it” and leave the main shot column, the shot now enters the choke area at the front of the jug. This choke, much larger than a conventional choke, just nudges the damaged flyers back into the pattern. The friction of the choke on the outer pellets also retards them slightly and thus lengthens the shot string.
The end result, in theory, is that with fiber wadded shells you keep the wad from pushing through the shot mass and “doughnut holing” the pattern, you return the barrel wall damaged pellets back into the mass of the pattern, and you lengthen the shot string.
That was the theory. I never found that any of it worked worth a damn. Phil Provence down at the US Army Marksmanship Unit in the early ’80s shot a Baikal Mu-8 and claimed wondrous things for it with the standard (then) marksmanship Federal T-123 fiber wad load of 32 grams of #10 shot at 1350 FPS (US measurement 3 feet from the bbl). They were certified ass-kickers and Phil claimed that his MU-8 would spread those billions of pellets all over the place. I patterned it and, although it was a bit more open than Matt Dryke’s Remington 3200 (IntSk Olympic gold Los Angeles ’84), it did not look like anything special. Bill Clemens, also at the USAMU and world record holder at that time under the post ’76 rules) was shooting a Perazzi Comp I also with factory jug chokes and vents. They all seemed to pattern about the same. Remember, the actual patterning that we did was two dimensional. We had no way of measuring shotstring, but these were the considered opinions of some pretty experienced shooters. No one gun seemed much better than the other with that Federal T-123 thumper.
My personal experience of owning jug choked IntSk guns has centered about Perazzi, S&W 1000 and Krieghof. I have never owned a Rottweil Olympia. Although seductively balanced and with beautifully proportioned pistol grips and forends (the most comfortable I have ever tried), I always felt them a bit fragile for heavy competition usage. The later ones were improved, but the early Rottweils were letting go at the barrel/monobloc juncture and simply ate firing pins. Dry firing was verboten!
Do plastic or felt wads make a difference? My Krieghof and Perazzi jug choked skeet barrels shot plastic wad loads more uniformly than fiber wad loads, but remember, I competed when 32 gram loads were permitted. I have not done any work with the current Olympic 24 gram loads, but I do know that the many of the US IntSk shooters are going to 30″ barrels and chokes a bit tighter than skeet. Those doubles on four make a difference when those International speed birds go zipping along. Some on the current US team use K-80s, but I don’t know if they are jugged guns. I am not sure that Krieghof makes a jugged 30″ barrel.
Your letter indicates that you shoot in England. I am not familiar with the rules for English style slow skeet, but if they are the same as we have for American-style NSSA skeet, you can still use 32 grams, or at lest 28 grams. No American style skeet shooter I know uses fiber wads in 12 gauge, although some do shoot the K-80 jugged 12 gauge skeet barrels which would be somewhat similar to yours.
By the way, the best skeet patterns I ever got were from a conventionally choked Krieghof M-32 skeet barrel with Federal 32 dram standard velocity skeet loads and #9 (US size) shot. The worst patterns are with the mass produced factory screw in chokes currently being produced by Browning/Miroku and Beretta. The original Browning short Invectors were absolutely the worst that I have seen, but there is probably something out there even poorer. One advantage to screw chokes is that you can always throw them out and cut some more.
Bottom line, there is too much shell to shell variation to give you good advice, especially since you may well be using different shells than we have available. I do know that nothing miraculous is going to happen if you go from plastic to fiber. I found the plastic better. Let me know what your experiments prove.
Shotgun Report’s Technoid