Over-boring a .22lr barrel

[MontanaLon]

Welding and gun barrels don't go together. The weld will pull the barrel, it will not be straight.

It's been done for years. Drill a hole through muzzle device into barrel but short of bore. Insert a pin into the hole and weld the pin in place. Usually everything is steel, barrel, muzzle device and pin, but I think if you used an aluminum pin and an aluminum tube it could work. The weld doesn't have to connect the barrel and pin physically, just make it so the pin cannot be removed without grinding off the weld.

 

[38super]

Welding will affect hoop stress. If a barrel muzzle is welded, back bore past the weld area.

 

[Tolerent]

Welding will affect hoop stress. If a barrel muzzle is welded, back bore past the weld area.

I wonder how hoop stress even on a massive centerfire would compare near the muzzle to down the bore a ways. I'm not capable of doing the calculations but we are talking about a .22LR. My muzzle on the barrel in question is beefier than the chamber on my SR22 pistol which would have perhaps more pressure by some margin. Looking at the barrel I can't really see a lighter barrel muzzle on the 10/22 than on some of my .223 with 10 times the kinetic energy.

That blurted out... I would want to be conservative and avoiding stress risers does seem to be a safer path.

 

[Tozguy]

Use epoxy instead of weld. My approach would be to cut the barrel to length and crown it for durability. Fit a long aluminum tube over the whole barrel and epoxy it in place. Provide for a means of aligning the tube to the bore by sighting through the barrel while the epoxy cures. The bullet will start falling as it exits the rifling so the id of the aluminum tube must be generous. Worse if the rifle is not held well by the shooter. If the bullet touches the tube in any scenario accuracy will be horribly dangerous.
Its an interesting exercise but it would be so much simpler to buy subsonic ammo. I have used some Remington subsonic that was reasonably priced.

 

[Tolerent]

Use epoxy instead of weld. My approach would be to cut the barrel to length and crown it for durability. Fit a long aluminum tube over the whole barrel and epoxy it in place. Provide for a means of aligning the tube to the bore by sighting through the barrel while the epoxy cures. The bullet will start falling as it exits the rifling so the id of the aluminum tube must be generous. Worse if the rifle is not held well by the shooter. If the bullet touches the tube in any scenario accuracy will be horribly dangerous.
Its an interesting exercise but it would be so much simpler to buy subsonic ammo. I have used some Remington subsonic that was reasonably priced.

I love the thought process of sleeving the barrel full length. This is a contoured barrel so a bit more difficult but still sleeving a bit similar to a morse taper fit seems doable. Especially with a thin epoxy bond layer.
Regarding the barrel jump while firing: the projectile is traveling between 960 and 1060 fps with one exception for the 90 rounds I tested from a similar 4.5" barrel from a charger pistol (that was not extended) with my bulk ammo. Adding 12" is not going to be twice as bad as adding a suppressor and those often come with only .03 overbore so any barrel sleeve strike would be unlikely at an overbore of .06 and if there was a sleeve strike it would really be mild rub and not a hard contact. A non event in regards to mechanical safety. The only concern would be the same concern I would have from any sudden barrel deflection while discharging the firearm.

Couple edits:
1. the 4.5" barrel on my charger pistol leaves about 3" of foregrip without a barrel resting on it. Really dangerous. I am installing linear compensator on those 3" as a guard to keep my fingers out of the path of bullets. Really dangerous with unutilized foregrip. I am needing to upsize the chase in the foregrip to allow for the compensator as my charger came OEM with a contoured barrel. Lots of sanding.
2. See the post below.

 

[MontanaLon]

Epoxy would not satisfy the law on SBR's.

 

[seasicksteve]

Epoxy = Felony . If an extension is added to bring a short barrel to legal length it will need to be blind pinned with a weld over the pin or permanently attached by welding or brazing. Low temp solder also will not satisfy ATF. Get a tax stamp and make it an sbr

 

[Tolerent]

Epoxy = Felony . If an extension is added to bring a short barrel to legal length it will need to be blind pinned with a weld over the pin or permanently attached by welding or brazing. Low temp solder also will not satisfy ATF. Get a tax stamp and make it an sbr

Hence my interest in maintaining the original barrel length. My $200 stamp is going to be attached to a suppressor I can mount on any of my threaded .22 barrels rather than the barrel length of one SBR where having a shorter barrel is not important to me.

 

[FanMan]

If you're worried about crowning the muzzle end of the rifling portion deep down inside, DIxie Gun Works sells .22 barrel liners in various lengths. Bore the entire barrel 5/16", cut the liner to the desired length and crown its muzzle end as desired, and solder or epoxy the liner in place.

 

[Tolerent]

If you're worried about crowning the muzzle end of the rifling portion deep down inside, DIxie Gun Works sells .22 barrel liners in various lengths. Bore the entire barrel 5/16", cut the liner to the desired length and crown its muzzle end as desired, and solder or epoxy the liner in place.

I anticipate this could be my final solution. Before getting this far though I plan to let the bored to muzzle crown demonstrate for itself whether or not I can rely on it without drilling out the last 4.5" and installing a partial liner.