choke tube what it says?

[big bore 45/70]

Picked up 3 choke tubes yesterday too try in my 870.
I true the packages away. So this am I was checking to
See what choke was what size. So I got my mic.out
And was mesureing them .the one was stamped .660
But my mic. Says it's a .640. Has anyone run into this
Before. ?

[spurman]

Yes I have, Package says it is .643 choke measures .666

[SKFOOTER]

Are you sure that you are miking it properly??

[spurman]

Yes I am sure. I am using a Vernier Caliper that will measure the inside of the tube.

[allaboutshooting]

Picked up 3 choke tubes yesterday too try in my 870.
I true the packages away. So this am I was checking to
See what choke was what size. So I got my mic.out
And was mesureing them .the one was stamped .660
But my mic. Says it's a .640. Has anyone run into this
Before. ?

Ports can sometimes cause a reading that is larger than the actual parallel section or muzzle exit diameter. It's important to measure the "solid" section of the choke tube.

Sometimes a choke may also be accidentally marked incorrectly by the manufacturer. I've seen that happen as well.

Thanks,
Clark

[big bore 45/70]

And all the other chokes read correct. As stamped.

[allaboutshooting]

And all the other chokes read correct. As stamped.

Industry standards normally allow some variance +/- a few thousands of an inch. The example that you gave of being marked .660 and measuring .640 would be out of tolerance and would probably be the result of an error in marking the choke.

Maybe a year ago, a very nice man sent me a pretty high-end choke tube that he was having trouble getting good patterns from and asked if I'd shoot it through one of my guns, just to see if it was his gun or the choke. I shot it through my 835, 935 and SSi-ONE and the patterns were, kindly, terrible. I measured it and instead of being .675, as marked, it was .640, an obvious error on the part of the manufacturer. Things like that do happen but in my experience at least, not very often.

Thanks,
Clark