Three steps to loosening anything rusted or stuck, perform in this order:
1: Soften or remove corrosion.
2: Apply torque with correct tools.
3: Heat as required *as you apply torque* (does two things: Reinforces (1) above, and also mechanically changes dimensions of the heated metal as it expands faster than the substrate material to which it's adhered either by corrosion or by mechanical friction).
So for the corrosion:
Take a 50/50 mix of Coca-Cola (use the real stuff, not "diet") and diesel fuel, and soak it overnight muzzle down in a cup. The tiny amount of phosphoric acid in the Coke dissolves any rust, and the penetrating qualities of the diesel will get the solution in where it counts. This is an old trick used afloat on boats, and I've found it VERY useful in mechanical work as well. Give it a shot and I'd bet that it'll free up. Give it a 24 hour soak.
Other stuff works too... automatic transmission fluid and acetone, Kroil, PB Blaster, Liquid Wrench, a mixture of citric acid and diesel, "pick whatever". Coke and Diesel is pretty gentle and is cheap.
THEN:
Naturally you will need to apply torque using correct tools and a vise, as described above. Wood blocks carved to fit the diameter of the barrel and clamped in a vise if needed, dusted with rosin if needed, etc. Just use good normal mechanical techniques.
And there's no harm in heating it with a torch, either.
"In the end with about three repeats of the entire process, I ended up using a breaker bar in the choke wrench, along with soaking and heat (never over 200 degree's) and a well padded vise on my work bench to finally get it to let go."
The reason you struggled is that 200 degrees of heating didn't do squat. You might as well have stuck it in ice water for all the good that did. You need *heat*, as in "use a propane torch without worry" and "use an oxy-acetelyne torch if you know what you're doing".
Willie
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