Help, please!

How do I measure the choke constriction of a .410? I have this ID caliper:


It goes less than two inches into the tighter barrel, and slightly over 2 inches into the more open barrel. Any suggestions on how to measure the chokes? Without a known barrel size?

Do I measure a known distance of this caliper and then adjust based on what the dial says? But that would give me the diameter of the opening of the barrel / muzzle, not necessarily the "choke," right? Because I don't know the diameter of the barrel.

Does it appear to hit a parallel section? If so, and that's approx. .410", that may be the barrel ID. Depends on how long the taper leading into the cinal choke diameter is. I have a similar gauge and measured my Browning M42 by using a telescoping gauge to determine the bore I.D.(.407" in my gun). The choke measures .396". My choke is therefore .013". The barrel is marked "Full". Skeet targets believe it is full, when I center one. I have a Skeets bore mike set but it only goes small enough for a 28.

After you measure them, but before you open them up, pattern them and see how they pattern. I have a beautiful English made .410 with a half and full choke. But when I patterned the gun each barrel patterned exactly the same. I guess that falls into the wonders of shotgunning 101 ?/?/?

Tim

Ben, you can't use those internal calipers to measure the amount of constriction in a .410 because the steel arms are just too wide to allow enough reach into the bore. Bore diameter is irrelevant, choke diameter is irrelevant. What you need to measure is the difference between the bore ID and the choke ID. Nice to know choke taper, but you can't get it with that tool.

If you are willing to relegate that tool to a somewhat fragile status, you can try filing down the wide part of the probes so that you can get more reach into the bore. Max depth on that tool is 3.25" under the best of circumstances.

http://www.doublegunshop.com/forums/ubbt...ge=2#Post114189

Thank you all! I am going to try shaving off some metal from the legs...