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Barrel stub help

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Olddaddy

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I’m looking for someone willing to do the threading for a stub barrel project. Barring that, someone willing to hand hold me through the project. I have a 20 ga HR barrel for the stub and will buy a blank for the barrel. I’ve got a lathe, but no threading tooling. I’m fairly competent, but not fairly confident. Advice and help greatly appreciated.
 

Olddaddy

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Sure, I'm building an H&R Classic Carbine that I want chambered in .327 Federal. I have an SB2 receiver and a 20ga barrel for the stub. I'd like to end up with a barrel somewhere between 16"-18". I'm not concerned about taper on the outside of the barrel, it can be straight.
 

derf

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I've built many muzzle loading rifles on the same set up. Cut the barrel off right where the contour starts, about 1/4" ahead of the lug. I bored the stub and tapped for 7/8-14. Thread the barrel and screw it in. Then you need to cut a groove for the extractor. You will have add to the extractor claw so it will reach the rim on that case. I don't believe H&R parts are available anymore.
 

epanzella

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I thought about doing this but was concerned about wall thickness. I wanted a .458 bore smokeless ML. How much is minimum for the thread to be safe?
 

derf

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I have no idea what minimum thread size would be, that's why I went maximum. I mated up surplus .50 cal barrels to the stub with 7/8-14 thread. I also used a 5/8" dia. breech plug approx 2" long that was simply a slip in fit, using an "O" ring and a tapered nose for sealing out gases. It had a built in extractor that laid over the shotgun extractor to eject the 209 primers when the breech was opened. I drilled and tapped a 1/4-20 hole on the left side of the barrel and used a dog pointed set screw to keep the breech plug from rotation and ejecting with the primer.

If I were to build one for smokeless powder, I would make the barrel solid all the way back and tig weld the lug to it, like the factory Handi-rifle barrels.
 
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Lordbeezer

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Turn your barrel to fit inside the shot gun barrel.epoxy it in..no threading needed..
 

derf

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That would be the easiest way, providing the shotgun barrel is still intact....
 

derf

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I think you are misunderstanding the situation. He's speaking of sleeving the shotgun barrel with a rifle barrel. In this case you would leave a shoulder on the rifle barrel that seats inside the shotgun barrel. The chamber area of the rifle barrel would be the same size as a 20 ga. chamber, and the rest of the diameter is still larger than most pistol barrels. All the epoxy does is hold it in place.
 
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Lordbeezer

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Exactly ..easier than soldering .can use piece of brass or loaded round to set headspace .can use same forearm.op said he had a 20 ga barrel..nothing wrong with stubbing barrel and threading.
 

epanzella

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I think you are misunderstanding the situation. He's speaking of sleeving the shotgun barrel with a rifle barrel. In this case you would leave a shoulder on the rifle barrel that seats inside the shotgun barrel. The chamber area of the rifle barrel would be the same size as a 20 ga. chamber, and the rest of the diameter is still larger than most pistol barrels. All the epoxy does is hold it in place.
I understand how to stub a barrel but the cartridge the OP is considering is going to put 45000psi against the breechblock. The glue has to resist this so that the stub doesn't come forward out of the barrel sleeve. I see threaded stub jobs all the time but I never heard of using epoxy. A muzzle loader would be different as the threaded breech plug would contain the pressure but a centerfire chamber is only as strong as it's weakest link. You still need to turn the barrel blank, cut the existing barrel, and bore the taper out of the factory shotshell chamber. Why stop 3 feet from the finish line? I would thread it.
 
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Lordbeezer

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Was not talking about gluing a barrel onto a stub.cut matching steps in shot gun barrel and barrel blank.with proper fit barrel can not shoot out the front or have head space issues. i would be worried more about bolt thrust than however the op decides to modify his barrel..
 

Silverbullet

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Explain it like sex , male part rifled barrel , female part old barrel on gun with as it was made . You put rifle barrel inside with epoxy , they mate and lock up never to move again.
 

epanzella

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No matter how tight you fit a barrel stub to a factory shotgun chamber, the breech end will be loose because the factory chamber is tapered. Assuming you can get the stub barrel centered in the big end of the chamber, the epoxy would have to take up the extra clearance. You still need a lathe to do all the prerequisite steps so why not thread it too? I guess we'll have to agree to disagree.
 
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Lordbeezer

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The op said in first post he didn't have threading tools.but he does have a lathe...most if not all the time you cut step(s).into both barrels.if barrel blank is too small for 20 ga chamber 3 set screws can center new barrel into old barrel.then cut heads off and polish...just another way to do it..
 

epanzella

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Just finished mine. It's an H & R 12 ga converted to 458 Smokeless ML. The blank & stub are threaded. The front scope mount and forend mount are TIGed to a barrel band that sits against a shoulder machined into the barrel and held in place by two set screws hidden by the forend wood.


DSC_0699.JPGDSC_0701.JPGDSC_0702.JPG
 

epanzella

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Just finished mine. It's an H & R 12 ga converted to 458 Smokeless ML. The blank & stub are threaded. The front scope mount and forend mount are TIGed to a barrel band that sits against a shoulder machined into the barrel and held in place by two set screws hidden by the forend wood.


View attachment 291323View attachment 291324View attachment 291325
Just a followup. Gun shoots great with 53 gr RL7 pushing a 200 gr XTP with Harvester blue sabot. Groups ranged from 5/8" to 1" @ 100 yds. grp 1 may 3 2019.JPGgrp 2 may 3 2019.JPGgrp 3 may 3 2019.JPG
 

john.k

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Actually, with a good fit ,you dont even need epoxy......I made a liner that was what engine machinist call transition fit,test fired it without any glue ,and the liner was stuck,would not come out.......which was upsetting,as I had not finished the job.....the maximum projected backthrust of a small base case is only of the order of 3 to 4 tons,and that doesnt allow for case strength,which is proved to be near enough in itself in small cases ....CF the Winchester self loaders ,SMG s etc.
 

Jim Davis

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What's not generally recognized is that the greatest force working to pull the barrel out of a stub is the recoil of the gun versus the inertia of the barrel. The passage of the bullet exerts only the tiny instantaneous energy generated by the push of the bullet against the friction of its passage. If you can't pull the barrel out by hand, it won't come out when fired.
 
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