I'm planning to jug choke a single barrel auto loader that is currently true cylinder. I'd like to get about .08 of choke. I have the tooling and I've opened barrels in the past but never tried to jug choke. My plan is to open the barrel (plenty of wall thickness) about an inch below the end of the barrel using an adjustable reamer.
Before I embark on this, am I missing anything? Any pitfalls to be aware of?

Thanks very much,

GregMc

Adjustable reamers are not truly parallel they will have a lead in taper because they are designed to be used by hand having a square top section to fit tap wrenches , the types I have used they are designed to pass all the way through the hole or bore you are sizing because of this lead in taper.

Thanks damascus. I was sort of counting on the taper as part of the jug choke. Is your suggestion that I back bore the entire length of the barrel from the receiver end and leave an inch or so of choke?

Greg if you are talking about the type of reamers in the photograph, I would not in any circumstances use this type of reamer for a gun bore. This type of reamer I know as a Repair reamer sometimes called a "spill bore reamer" on this side of the pond used to adjust motor pulley bores and hole sizes because of their construction they are not truly round because the cutting blades and the slope the blade runs in the reamer body are cut separately and not ground true as one unit because of its design. If you try to ream a a long bore the reamer will wander also their finish leaves a lot to be desired. These reamers are quick fix engineering items and work extremely well for what they where designed for.