Shotgun barrel rehab?

[Pork Fat]

I picked up an old Ithaca Model 37 12 gauge at an auction for $100.
The bore just looked dirty, action seemed smooth, finish showed honest use.
Modified choke, 26" barrel- A spare gun for someone to use when we shoot
hand thrown clays out in a field.

I get it home, start to clean it, and yuck. That barrel must have been used
to shoot very corrosive junk (bird scare bombs, flares, something with black powder in it), not cleaned EVER, then lots of regular shells.
Lather, rinse, repeat.
Now SHREDS of wadding plastic adorn this crusty sewerpipe. I used a brass
brush on a piece of aluminum cleaning rod chucked in a drill with Naval Jelly.
This was just so I could assess the bare metal, but I never got to that point.
The brush filled with plastic, the Naval Jelly escaped the bore to remove bluing
(duh), and I valiantly put the project aside.:banghead:
Haunting the "Fred Sanford" tables at gun shows yields no replacement barrels. Gun Parts Corp. shows nothing (Early series of Ithacas won't accept
late- model barrels).
So finally, here are my questions-

Can a shotgun barrel be reamed back to health?
Is it worth putting money into this dog?
How much would it cost?
If it could be done reasonably, would I lose the choke?
If I lost the choke, Poly-Choke or cut down to 18" for special social occasions?

Thank you for listening, I have held this terrible secret for 5 years.

I promise, no more kitchen table 'smithing for me.

 

[HSMITH]

Get a can of Chlorinated brake cleaner. Take it outside, and shoot it down the bore. The plastic will come out almost melted, no labor involved. Use at least half the can, total cost about $2 at the most.

I would then look at the bore, it it looks nasty yet I would wrap a tight patch on a bore brush, chuck it in the drill and coat it with JB Bore Paste. Scrub the barrel while turning at a medium speed, do this a couple times. Clean normally and inspect, should be fine unless it has big pits. Even if it is pitted mildly it will still shoot just fine.

As far as the finish loss, well, now you know.

 

[Pork Fat]

HSMITH- Thanks, sounds like it's worth a shot. Would the JB bore paste
be something on the order of a lapping compound? I'll have to find some.

 

[dfariswheel]

NO, the JB Bore Paste is NOT any kind of lapping compound.

It's an extremely fine, non-embedding mild abrasive specifically formulated NOT to abrade the metal or embed into the steel.

DO NOT use lapping compound in a gun barrel.

Another method of cleaning the bore is to get a well used old bore brush and wrap FINE steel wool around it.
Chuck the rod in your drill and run it at medium speed. making sure to keep the brush constantly moving.

This will clean out any fouling and will polish the bore.