I was "gifted" an 1970's Mossberg bolt action 12 gauge with a poly choke that's froze tight no movement whatsoever.I've used different spray lubricants numerous times,nothing.I know these are pretty cheap guns but its been project,it was pretty freaking rough when I got it so I'm restoring it.Any suggestions on how to get that choke working again?

Redneck penetrating oil. 50/50 acetone to ATF. Soak it and put a strap wrench to it.
If it already is not working, don’t be skeered to break it.

First, I'd put it in some transmission fluid and let it soak a day or two. Just pour the oil in a can or something and set the barrel in it. See if it'll give. If not maybe heat?

Sawzall

The best thing to free up stuck threads is wasp and hornet spray. No lie! Better than anything ive used. Apparently it has something in it to immediately dissolve the exoskeleton.

a 1970s mossberg might be a C-lect choke

either way if you haven't stood the barrel up in a jar of 50/50 ATF and acetone for a week that would be my first try.

finding a good way to grab it and hold the gun is also important

the poly chokes say poly choke right on them , the brass ring functions as the detent to stop rotation at each step.

they had an O ring in them that pressed the pedals of the choke together to create the constriction , if solvent ate that rubber it might have made a hard glue out of it as well as rust the very find threads

there were two types one silver soldered on the barrel the other threaded on

Good stuff. I quit buying Kroil since I found out about acetone/ATF for penetration oil.

Kroil works but it is so expensive

for stuff in a can easy to store in the truck I switched to Seafoam Deep creep , doesn't smell as much and in testing worked a touch better and less cost per ounce

it is all about the time , they all work given several days to work

I had some bolts rusted up on my truck I was Hanging on them flexing my 24 inch breaker bar , gave up and sprayed them down with Kroil well , sprayed them again 3 days later , at 5 days I put a wrench on them and though I has slipped off it broke loose so easy.

part of the problem with barrels is it is so hard to get and keep a good grip on them

I don't know how to put pictures on here,or I'd put one on here.The choke pictured is not the same one on this shotgun.Ill give the acetone soak a try.And you hit it on the head,trying to keep a solid grip while trying to twist the choke is a problem.I don't want to put it in a vise.

is this a bolt action Mossberg like a K195

does it look like this?

if you have a knurled section on the choke like the one in the picture and you have some strapping material make about a loop put the loop over the knurled part and start wrapping in the direction you need to turn it make about 4 wraps , then put the remaining strap material in the vice and clamp it down

you have just made a bench mounted strap wrench as you turn the gun you tighten the grab on the knurled part fairly evenly all the way around

depends what the gun is the best way to hold the barrel or action

when you get it all cleaned up I keep anti seize on mine to keep it moving freely

I suppose you could also pattern it and if it patterns well leave it

I was rather surprised how well the poly and c-lect chokes work I get a very good full choke with it in that setting.