Point Of Impact And Choke Tube Pressure


Bruce:

After reading your response and before a pre dinner pop I relaxed to the cogistative state about the subject. The dim bulb in this old head lighted up and I went again to the pattering board.

After thinking about the variables involved with choke tubes I patterned for POI using finger tight tube installation verses using a wrench. Lo and behold the POI on the top barrel came down to spot on which was repeatable until my shoulder said quit. The change in POI from tube to tube varied some what but deffinately the amount of torque applied had a significant effect. My normal practice is to use a Royal wrench and give it a slight “nip” when the tube bottomed . This caused the change in POI and using all the finger pressure I could muster would also but not as signifincantly.

While my bulb was still bright I compared the OEM tube clearance in the counter bore with the clearance on my other guns with after market tubes. The tolerances on the after market tubes is much less.(Briley and Seminole). Perhaps Seminole knows something since they design to use finger pressure only.

Next time my bulb gets higher and ambition matches it’s glow I will try the same experiment with the old guns with after market chokes.

Best regards,

John

Dear John

Verrry interesting. What you are saying is that someone’s machining is screwed up. That’s why you ALWAYS have to pattern and test for point of impact. You did the work and found the answer. I can’t tell you how many people writ me to ask which aftermarket choke tubes are “best”. You just can’t tell without doing the testing. I’ve had OEM tubes win the performance tests and lose them. It just depends. You don’t know until you pattern.

By the way, I’m not a big fan of finger tightening chokes. Like you, I use a Royal wrench with a little light tug at the end. I just hate it when my choke tubes come loose and they don’t with a wrench. Also a wrench is faster than fingers. Still, it’s nice to hear that my good friend Manual Dexterity wins a round every now and then.

Best regards,

Bruce Buck
The Technoid writing for Shotgun Report, LLC
(Often in error. Never in doubt.)

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