Making 32 ACP barrel insert for 12 ga

[preventec47]

Making 32 ACP barrel insert for 12 ga

I have an old JAP 7.7 barrel that is all rusty on the outside but has
the perfect chrome lined bore from 1943 and since the bore size at
.312 is perfect for .32 ACP I want to turn the barrel on a lathe
to resemble a 12 ga cartridge with some barrel attached that will
be snug fit into NEF single shot 12 ga gun.

I have a friend that has two upscale metal lathes and I thought I
would toss the idea here first for any pointers. I plan to cut the
chamber off the 7.7 and then find a way to ream a new 32 acp
chamber into the barrel where it is shaped like a 12 ga cartridge.

Initially I wonder if I need to weld up both ends of the barrel
so the lathe will have someway to find the very center of the
barrel before I start turning the barrel.

I plan to shorten the 32 acp barrel so that there will be a foot of
open shotgun barrel for the bullet to travel before exiting
the shotgun barrel.
This will allow all hi pressure gas to slow down before exiting
the shotgun barrel and it should be a very very quiet round.
Almost like a legal silencer I hope.

Any suggestions or pointers ? I may try again with 7.62x39
with another barrel if this works out. I wouldnt shoot a 7.7 JAP
in the shotgun because that would be too powerful.

[Mooseman684]

For .32 acp you will only need about 6 inches of barrel as an Insert. The barrel should not be welded as the bore should be centered already, and so a live center will fit in the end of the Barrel.You use Dial indicators to center it in the Headstock chuck... The problem you may encounter is the chrome lining...When you rechamber and you hit that chrome lining, it will start to peel and flake, IF you can even get a chamber reamer to Cut it...
I would buy a rifled bull barrel like a Pistol barrel Blank that wasn't chromed if I were going to build an Insert like that. Question...What are you going to do about the extractor ???
Rich