weaver chokes
I do not remember ever seeing any adjustable versions of the weaver choke. The body with the vent holes is not meant to be removed, and should not be without a thread filler i.e. tube when fired, to minimize the threads being contaminated with fouling.
I have made replacement tubes for weaver chokes out of the same heat-treated steel that I use for my other custom chokes. Original chokes are aluminum, and more easily dinged or distorted by hard shot pellets.
Any "proper" installation of a choke or device should always have the original choking removed to a straight cylinder configuration. A very tiny amount of remainder constriction is not a big deal, but if some part of the original choke is still there, it will have first crack at the shot.
Once you start the choke constriction process, you do not want to stop for a significant distance and then try to add more choke effect. Double choking in this manner will not give a tighter pattern. It is close to the effect of jumping berms with a motorcycle and hitting the top of the next slope. The shot is then going to be more distorted and sent on collision course with the other pellets that don't hit the "berm", i.e. choke. It is the outer pellets of the shot column that contact the secondary choke.
Another way to look at them is the double billiard strike. Double-tap a cue ball and see if you get the effect you expect.
I have a few examples of barrels with chokes installed with a remainder of the original choke present. I may post some pictures or do an article with them included at some time in the future.
[email protected]