Machinist advice for making a Handi stub barrel and the exact procedure to do so.

[Moleman-]

It might be a sickness, but I like making barrels. Generally I'll start with a drawing of what the barrel measurements/threads are. GMB has offered their gunsmith blanks marked on the chamber, muzzle, and some are unmarked. It's best to see which end has the most runout as it's the muzzle end. Sometimes one end will have a rough chopsaw cut and that is usually the chamber end, but it's best to measure. From there I center with a pin gauge in a 4 jaw chuck to face the ends and centercut them with a center drill. As long as the barrel is centered the tailstock doesn't have to be centered as the bit will still want to cut a 60 degree taper. It's usually best to take a skim pass between centers. I use a chuck mounted center in the headstock and a live center in the tailstock. You can use a faceplate and dead center in the headstock, but it's faster to just center the chuckable center. Mine has a step on it so it cannot be pushed back into the chuck. If making a stepped barrel you'll have a more ridged setup if you only have the section of barrel out of the chuck that you're working on. For contoured, steady or follower rest if you're getting chatter or deflection. You get a feel for speeds and feeds which will be different from start to finish as the diameter changes and also different between bore sizes (wall thickness) and alloy. If you get chatter the best advise I was ever given was to get ahead of it or behind. It doesn't happen often, but occasionally you'll get a barrel that just wants to chatter. I change the depth of cut and feed rate until it stops. For me, HSS is much more forgiving than indexable carbide in a manual machine. Usually I'll turn a barrel with indexable carbide, but when I get one of those barrels that wants to chatter I switch back to sharp HSS.

Few pics. Start of a uzi barrel from a GMB long 9mm blank that has been skim cut between centers. M72 Mossberg 375 blank being turned between centers (ended up making it octagon so it wasn't really needed). Centering an AK barrel for chambering using a pin guage. 1891 mauser barrel with blue tape used to support the barrel while chambering and threading. A few completed AR barrels

[country gent]

When working between centers I have the shouldered center I put it in the 3 jaw and take a light pass at 60* with the compound. Its then running dead true and straight with the spindle. If you need a dog it can drive on one of the jaws. Mark the drive jaw with a marker or tape you can then remove to check threads or fits and remount in the same location and not have to recatch threads or profiles

[Jim22]

I agree about making a small rifle for the .32 S&W Long. I havd one on a rolling block action. If you want some of my research here is where my post is:

https://castboolits.gunloads.com/sho...-Heavier-Loads

Jim

[405grain]

Excellent setup Moleman. I also use pin gauges to index the barrel off the bore when I'm using a 4 jaw. My lathe only has 24" between centers so I can't turn a barrel full length if it's over about 18" long. I needed to get creative so I made a spider that fits on the back of the headstock, and I can center both ends of the barrel as it's passed through the spindle. The first thing I do on a barrel blank is cut the shank and threads with only about 4" sticking out of the chuck. It doesn't matter if the OD of the blank is centered, the bore axis is what matters, and I'll take a skim cut on the exposed barrel OD so that it matches the bore axis anyway. Once the threads are cut I short chamber the barrel. It's better to get this done before contouring because it's much easier to hold and machine on a cylindrical surface than a tapered one. Besides, if something goes wrong it's easy to just cut and thread a new shank and then deepen the chamber.

Contouring a barrel is a little bit of a pain because I can only turn about half the length at a time. First I'll contour the muzzle end half of the barrel between centers, then rotate the barrel so that I can turn the breech end. I've got a set of flexible collets so that I can chuck up the now tapered muzzle end of the barrel, and a live center in the tailstock centers up the breech. Once the barrel's rough contoured files and sandpaper finish the job. The last thing to do is center the bore axis at both ends while the barrel is inside the lathe spindle, then crown the muzzle while everything is perfectly aligned. Carbide inserts are good for hogging off the metal, but as soon as I start getting chatter is switch to a HSS cutter as well. (FYI: on other forums you know me as Boltlug)

[Moleman-]

405grain/Boltlug! Watching your 30-30 thread on the other site, pretty amazing action and slab of wood into stock progress! My Sheldon 12x36 lathe's headstock is about 21" from the face of the lugs to the back of the spindle. Once there is a few inches of barrel sticking out in front of the jaws, most of the barrels I'm making are too short for a normal spider so I use the tape trick. I do have a spider and will occasionally dig it out for longer stuff that I want to be as accurate as possibe. Most of the barrels I'm making are for short range stuff so I just use the blue tape as it's quick to setup and I can live with the error. I also like tenon threading/chambering/test firing before contouring if possible. The mauser barrel above was fired duct taped to a board. Most of my stepped AR type barrels are threaded/chambered/test fired before profiling as it gives you the most options in case of an oopsie.

[Rockindaddy]

Turn your rifle barrel to a slip fit. A shrink fit is difficult. You may get your insert barrel half way inserted and the shotgun barrel shrinks and your rifle barrel warms. Now you have a mess! Use Locktite. I have used it many times. Have even soldered liners in over the last 50 years. Locktite works best. If you want to remove your insert you warm up your barrel and slide the insert out. You sure you want to create this? The finished rifle conversion will be heavy. A 20 ga shotgun would be better suited to your needs.

[corbinace]

Wow, I had to be gone for a day and I have a wealth of information to digest. Thank you one and all for the tips, methods and tricks. After reading a bunch last night I am seeing that this is not the easy project I had originally thought. Not that I am deterred in any way, just enlightened.
I am still incorporating the steps presented into my master word document.

I just read the email from Green Mountain that my barrel is on the brown truck.

I will be visiting my SIL (lathe holder) tomorrow and will be taking apiece of 1" cold rolled bar stock along to try out some of these tricks on an throw away piece of steel.

[corbinace]

Turn your rifle barrel to a slip fit. A shrink fit is difficult. You may get your insert barrel half way inserted and the shotgun barrel shrinks and your rifle barrel warms. Now you have a mess! Use Locktite. I have used it many times. Have even soldered liners in over the last 50 years. Locktite works best. If you want to remove your insert you warm up your barrel and slide the insert out. You sure you want to create this? The finished rifle conversion will be heavy. A 20 ga shotgun would be better suited to your needs.

I think I have gravitated to your way of thinking with epoxy. After working with the document that Kenton sent me, I got kinda skeered. Especially at the mention of no way to get it fixed nondestructively if I miscalculated. Kind of what you said.

I am aware that it will be heavier than a shot barrel and am OK with that given my intended usage. And I have a Topper JR in 20ga.
This particular donor barrel has catastrophic damage that will not clean up at 18" so it is only good for a tent stake at the moment.

Thank you for your thoughts and for taking the time to type 'em up.

[country gent]

Think the project theu decide on order of work to be done, Now do one step at a time concentrating on it alone then move on

[Jedman]

^^^^^^^^^^^^ What country gent said is great advice !
You have got this far by thinking things out and this is not that difficult to do. You will do well !

Jedman

[GONRA]

Somewhere in the 1959-1962 era GONRA made a 12 inch Luger barrel for a $35 1916 DWM "shot out bore" SGN Luger.
Remembered the 55 degree Whitworh treads, made brass plugs to center the Numrich Arms barrel blank
(driven from a lathe dog) and laborisly machined a front sight base using lathe apron asa hand shaper....
Bla Bla Bla....
Functioned / shot great, BUT windage was off! !! @#%^& Never figgered out WHY. Oh Well......
Great Moral Lesson 'chere - be prepared for dissappointment. Lottsa secret tricks in barrel makin' I guess! !!

[jdsingleshot]

Couple of things.

I guess it's obvious, but it's far easier to do this rifle barrel project by just cutting the shotgun barrel right at the front of the chamber. You can make the stub to epoxy in or thread the stub and the barrel shank for a mechanical fit.

And, if you are tapering the rifle blank, I can't see how a follower rest would be usable. The surface would be continually farther away from the rest as the cut progresses (or crowding the surface if cutting the other way on the taper).

[Texas by God]

If you cut the shotgun barrel even with the front of the forend, you avoid having to fit a new forend or create attachment for same.


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[corbinace]

Couple of things.

I guess it's obvious, but it's far easier to do this rifle barrel project by just cutting the shotgun barrel right at the front of the chamber. You can make the stub to epoxy in or thread the stub and the barrel shank for a mechanical fit.

And, if you are tapering the rifle blank, I can't see how a follower rest would be usable. The surface would be continually farther away from the rest as the cut progresses (or crowding the surface if cutting the other way on the taper).

If you cut the shotgun barrel even with the front of the forend, you avoid having to fit a new forend or create attachment for same.


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jdsingleshot, I have opted to use the longer stub method Texas by God speaks of, for the exact reason he mentions.

My forend is of the type that clips onto a stud and not the screw-on type found on the majority of Handis.
The stud on the bottom of the barrel would be an extra challenge to locate, as I cannot just mark it through the nonexistent hole in the forend. Then the next challenge is that the forend is held snug by the contact with the barrel and I need the profile of the barrel to be exact in order for the clip-on forend to be snug and not rattling. All of these could be overcome by exact measurements and maybe some trial and error, but I thought I was challenging myself enough with the easy route.

The barrel will not be tapered any more than is needed to fit through the shot barrel. I envision more of a bull barrel look with the barrel being almost 3/4" (.725") in diameter and very short.

Thank you for your thoughts and efforts in helping me along.

[jdsingleshot]

Sorry, after reading so many comments I forgot you wanted to keep the forearm lug.

It's not too difficult to make or attach a lug. I made one for the .30-30 barrel I mounted on a '93 Remington shotgun receiver. I ended up soft soldering it and it has held up fine.

[jdsingleshot]

[W.R.Buchanan]

OK I read this and here's my .02

I would leave the Shotgun Barrel 18.5" long cuz it's gonna look like a SBS if cut shorter. I would make a Sleeve that looked like a Shotgun Shell or Snap Cap to fit over the "chamber portion" of the Rifle Barrel that mimics the Chamber of the Shotgun Barrel on the OD with a good snug fit in the chamber like -.002-.003 under the chamber ID. The same +.002 to fit over the OD of the Rifle Barrel. This Sleeve could be JB Welded to the Barrel, Hence the .002-3 clearance for the glue.

Then I would make another "Sleeve" for the muzzle end of the Rifle Barrel that is a slip fit in the Shotgun Barrel, IE: -.002-3 under the .729-.730 of the Cylinder Bore Barrel, and glued to the Rifle Barrel with the same glue.

This entire assembly would fit into the shotgun barrel and could be Glued into that as well if you wanted it permanent, but I would make it a "Slip Fit" in the Shotgun Barrel so it could be removed like a Sub Gauge Shotgun Barrel Tube. Another Idea: An O-Ring integrated onto the OD of the Chamber Plug and OD of the Muzzle Plug could make the unit a Solid Fit in the Shotgun Barrel if you didn't want to make it permanent. Well greased so you could push it back out if you wanted ?

There is no need to turn the Rifle Barrel at all and there is no need for an "Interference Fit on anything . The reason for this is that what you want to do with Shrink Fits has a Low Probability of Success due to the length of the barrels involved and trying to get everything together before it all locks up on you! Without the heat it is a simple Slip Fit and can even be done with Glue to make it permanent if you think it thru and want that end result.

I Highly Recommend not cutting any Shotgun Barrel off below 18.5" under any circumstances, as all it takes is one Negative Person at the Range to Rat you out to the ATF, and you get to spend time in Jail!

The Standard Toolmakers Rule for Making Adapters of any kind, is that you do not modify the Parent Part unless it is absolutely necessary. You make the "Adapter 'Fit' the Parent Part."

What I have outlined above would follow that rule, and would be the easiest way to accomplish what you are trying to do. Maybe not exactly like what you thought it should be, but and easily workable solution to your project. You can also Glue Rifle Sights to your Shotgun Barrel if you choose.

It would require about 1 foot of preferably 12L14 Steel that will turn really easily on your lathe and be available from McMaster-Carr for a Few $/Ft, and be easy to get a good result with.

Hope this helps you figure this out? And Please do read over this several times so you fully understand the process.

Randy

[country gent]

The only thing I would change with W. R. Buchanans way Is I would thread the muzzle of the barrel and the bushing so that the barrel could be tension in place helping to control the harmonics. A light face cut on the shotgun barrel to a square outer edge Leave the bushings outside large and blend when installed the joint wont show. The plus here is the bushing will pull on the rifle barrel and compress the shotgun barrel the opposing tensions should dampen harmonics and give the performance of a heavier barrel. This wuld be similar to the Dan Wesson barrel set up

[Texas by God]

Cutting the shotgun barrel below 18” isn’t illegal unless it is still on the shotgun- or remounted to same.
A chamber length stub or a 17-7/8” stub- once epoxied/ pinned/ threaded to the rifled liner- is now a legal barrel again.
The whole point of using inexpensive shotgun hosts is to come up with a unique, fun shooting single shot rifle for not a lot of money.
I’ve done the front and rear bushings to fit a 16” Uzi barrel inside a 20 gauge Topper like mentioned above, another good way to do it.
If your liner is small enough to begin with, this makes a lot of sense.


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