Choke gauge

[patt2007]

Hi, can anyone tell me what the sizes are of the chokes on a 12 bore, as I am wanting to make a gauge to check the size of the chokes on a gun I have recently purchased. Thanks Pat,

[wymberley]

Hi, can anyone tell me what the sizes are of the chokes on a 12 bore, as I am wanting to make a gauge to check the size of the chokes on a gun I have recently purchased. Thanks Pat,

 

Pat, as you're going to the trouble, is it fair to say that you'd like to do it accurately? If so, you may need to make two. One to measure the diameter of the choke and the other for the barrel at a specified distance down the barrel, ie, it'll have to be "long reach" - c9". You will understand that any degree of choke is the difference between the two.

[bedwards1966]

Ok, here is a page that tells you the measurments of constriction. A standard bore it taken to be 0.729", so you can figure it out easily enough.

 

However, you might be wasting your time. Choke is the restriction in relation to the bore, and many guns have different sized bores, it's now becoming common for all sorts of odd sizes to be produced. This means that you can never get a truly accurate reading off a gauge, the best you can hope for is to get somewhere close. Even if a barrel has the bore size stamped on it, it's not to be relied upon.

It may be possible to measure it out pretty accurately, if you really want to get it right then the only accurate way to tell is by patterning the gun, details of how it's measured are on the page I've linked to.

Edited April 29, 2012 by bedwards1966

[Andy H]

You need to measure the bore 3-4" from the muzzle and then the choke constriction to determine the true choke for that barrel , For example a 410 bore size can be from .405" to .430" so the stepped bore gauges that you can buy are useless as they are based on the perfect bore size for that particular

caliber.

Edited April 29, 2012 by Andy H