Jug choke

[mechanic]

Has anyone tried a jug choke?  I want to cut down a single barrel , and the cost of having reamed and threaded for screw in's is more than the gun is worth.  The jug choke looks like something I could do myself, with an adjustable hand reamer....

Ben

[BUGEYE]

I haven't done it, but a guy in missouri did his muzzle loader shotgun and it worked real well.
of course he had more barrel wall thickness. I don't know how that would come into play.
if it works, you could  save some folks here some money.

[spruce]

Certainly worth a try if the barrel walls look thick enough to you.

I think I'd leave enough length the first time I cut it so if it didn't work out I could cut off the "experiment" and still have a legal length barrel.  If it does work out the first time you could always cut it shorter and do it again.

Just a thought.

[clum sum]

Showing my ignorance, what is a Jug Choke?

[mechanic]

Showing my ignorance, what is a Jug Choke?

Metal is removed from inside the barrel so that the shot wad can expand, but then it is contracted again before it exits.  From my understanding in many guns this tightens the pattern significantly. 

To ream and thread a barrel would cost me about $100.00, plus the price of the choke.  I just ain't spending that on a shotgun I paid far less for.

It would make a good experiment anyway.

Ben

[gunnut69]

Thw jug choke is the only good way to chike bore a muzzle loader and Not have difficulty load ing the gun. This because the bore diameter stays the same other than for the relieved section. Remember the jug (relief cut) should be about the length of the shot column or a bit longer. The section in front (toward the muzzle) should likewise be the same length.. They are not difficult but require a pilot on the reamer to keep it centered in the bore. Always do this type work with the workpice verticle to maintain the cutters evenly cutting, not dragged down but gravity.  You really should measure the bore diameter several positions around the barrel and wall thickness at those locations.. The wall thickness is fairly critical but those old single shots when cut down usually provide plenty of meat.. If you remove too much there will swelling and perhaps splitting. Work to the thickness of the muzzle of the barrel being worked.

[mechanic]

Thw jug choke is the only good way to chike bore a muzzle loader and Not have difficulty load ing the gun. This because the bore diameter stays the same other than for the relieved section. Remember the jug (relief cut) should be about the length of the shot column or a bit longer. The section in front (toward the muzzle) should likewise be the same length.. They are not difficult but require a pilot on the reamer to keep it centered in the bore. Always do this type work with the workpice verticle to maintain the cutters evenly cutting, not dragged down but gravity.  You really should measure the bore diameter several positions around the barrel and wall thickness at those locations.. The wall thickness is fairly critical but those old single shots when cut down usually provide plenty of meat.. If you remove too much there will swelling and perhaps splitting. Work to the thickness of the muzzle of the barrel being worked.

Good info,
Thanks!

Ben

[Nobade]

Interesting that this should come up now. I have a new to me Navy Arms side by side 12ga muzzle loader that I would like to choke. I have read about jug chokes for years but never tried to do one. What cutters are used? Is it something like an expanding reamer that can be dialed bigger while in the bore? Any pictures or advice I can get would be great!

I have been shooting this shotgun a bit and have discovered it is deadly to about 25 yards, maybe 30 but beyond that patterns are pretty sparse. Muzzle loading shotguns sure are a lot of fun though, and I don't have to buy shells or load for it. Such a deal! 

[gunnut69]

I'm far from an expert but did a couple. I used an expansion reamer that could be expanded while in the bore to cut the recess or jug itself with a homemade brass pilot to keep things centered. Afterwards a choke hone was used to taper the entrance and exit steps.. The hone I used had 2 stones and is spring loaded. I believe it came from Brownells.. The old timers in Howe's book (I think that's where I saw it) used a home made reamer with a blade spaced out of it's recess by a screw tightened wedge. It looked a bit crude but removed metal very slowly and I believe it was hand turned.  All that's needed is to produce a recess in the bore relatively centered and of a known dimension so that choke amount can be adjusted. One could even use the hone by itself to cut the recess, though it woulld be a fairly slow process.  Oil is used to lube the hone..

[coyotejoe]

For several years I jug choked muzzleloaders as a small source of additional income. I used a simple hand cranked single cut reamer of my own design. There is no need for a pilot, it can't possibly cut off center. The reamer needs to expand and contract while in the bore and I don't know of any adjustable reamer with that capability. Mine was expanded by inserting a very thin tapered wedge under the cutter. That would be the L shaped piece in the photo. Pushing the wedge inward raised the cutter and withdrawing it allowed the cutter to retract. Major adjustments were accomplished by shimming under the cutter with strips of paper or aluminium can.
The first photo shows the tool disassembled for cleaning, the next as it comes out loaded with cuttings. You need to use plenty of cutting oil and frequently remove the tool and clean cuttings.
The most difficult part is how to measure progress. I used the telescoping gauge and micrometer but that is far from ideal. Brownells had a bore mike which would do very well but costs about three hundred bucks. Remember that to get a full choke requires a recess only about .020" deep, modified about .010-.015" deep and improved cylinder only about .005-.010" deep.
 I have tried doing it with an automotive wheel cylinder hone and did get an improved cylinder choke in a 28 gauge that way but it takes forever and wears out lots of stones.

[gunnut69]

That's almost the same as the scraper type cutter used by Howe but I seem to remember he drove the tool holder thru the bore and adjusted the cutter from the muzzle much as one would with an expansion reamer. I bought mine, if I remember right, thru EBay for a very little... I bought it mainly to expand the hole in 1911 bushings after tightening.. Also you are right the type cutter shown is a scraper, it only cuts sith a single edge. The expansion reamers cut with several blades emanating from the central core. They are held in alignment but the guide. They must be guided with a pilot. I've seen chokes ruined using unguided expansion reamers. The set has many reamers and their cutting ranges overlap..

[mechanic]

I got the barrel chucked up in the lathe at my work, but I only have a few minutes at lunch to tinker.  I'll 'get er done' eventually.

Ben

[Nobade]

Coyotejoe, I like your setup there. Pretty much what I had in mind. A couple of questions though, how long is the recess? Is there a rule of thumb to go by, is it critical? The other is where you mention dimensions, is that total or on one side? I.e. full choke takes .020" deep. Is that enlarging the bore .020" or .040"? One other, how far from the muzzle should it end?

I do have a three leg bore mic for 12ga, so at least that part is covered. This is going to be an interesting project.