Chamber repair

Licensed to kill said:
I have no intention of soldering. Locktite or accraglas. Condition of the bores snd value of the guns is of no concern and I have zero plans to have this done by someone else. I do these things to see if I can and learn how.
Click to expand...
I guess you could try the old thermal/cryogenic fitting! that might be fun.
 
sean69 said:
or liquid nitrogen .... but hey we are all made of money here - right ;)
Click to expand...
There are spray cans of cryo-coolants available if you look, often used troubleshooting electronics items. Not super cheap, but cheaper than having to buy a Dewar Flask for a rare usage.

Liquid propane works in a well ventilated outdoor space, according to my High School Science Teacher, who was a Tanker in North Africa in WW2. He said that capturing a couple of propane bottles from the Germans was "THE" score! You could put your beers in a sack full of stones, run a bottle of propane into the sack, and in a very few minutes, enjoy a frosty cool beer! :)
 
Shrink fits work great on larger objects, because the amount of growth becomes something that can generate some real clearance. Smaller pieces are tricky/ impossible unless you are able to accurately measure bores to the tenth or less, because the amount of interference/clearance is so tiny.
Lots of times guys brag that they are doing a shrink fit on something down around that half inch size. Personally, I think they are just guessing, and doing the final assembly with a hammer....
Which usually works just fine.
 
Jonnyofalltrades said:
Shrink fits work great on larger objects, because the amount of growth becomes something that can generate some real clearance. Smaller pieces are tricky/ impossible unless you are able to accurately measure bores to the tenth or less, because the amount of interference/clearance is so tiny.
Lots of times guys brag that they are doing a shrink fit on something down around that half inch size. Personally, I think they are just guessing, and doing the final assembly with a hammer....
Which usually works just fine.
Click to expand...
Exactly! If you are shrinking a part 0.1-0.3% that is a decent amount for a 4" plus size (fraction of millimeter we're talking) carbon steel.
For a tiny part it'd be microns... just not relevant
 
Yeah, good point on the shrink fit. On smaller parts, you have two issues, one being the coefficient of expansion (usually a multiple zeros after the decimal point number, per degree of temperature change, meaning that any meaningful shrink on a small part is gonna be a few tenths of a thou at best), but the main issue is that if your insert does not have some mass to it, as soon as it touches the body of the part it is meant to be inserted in to, the heat transfers from the warm part to the cold part, and it ain't cold (or shrunk!) no more!

We didn't need no hammers! LOL! A bolt a nut, and a couple washers, almost always did the trick! FWIW, CF-18 flight control surfaces, among others,which I dealt with for some years... The Technical manuals all said that ALL the shrink fits were supposed to be ~1 1/2 thou, which worked great in the 4+ inch diameter bushings in the Landing gear legs, but not so well in the sub-3/8 inch bushings we were most often installing!
 
trevj said:
Yeah, good point on the shrink fit. On smaller parts, you have two issues, one being the coefficient of expansion (usually a multiple zeros after the decimal point number, per degree of temperature change, meaning that any meaningful shrink on a small part is gonna be a few tenths of a thou at best), but the main issue is that if your insert does not have some mass to it, as soon as it touches the body of the part it is meant to be inserted in to, the heat transfers from the warm part to the cold part, and it ain't cold (or shrunk!) no more!

We didn't need no hammers! LOL! A bolt a nut, and a couple washers, almost always did the trick! FWIW, CF-18 flight control surfaces, among others,which I dealt with for some years... The Technical manuals all said that ALL the shrink fits were supposed to be ~1 1/2 thou, which worked great in the 4+ inch diameter bushings in the Landing gear legs, but not so well in the sub-3/8 inch bushings we were most often installing!
Click to expand...
Good rule of thumb is .001” or more per inch for heavy fit, .00075” per inch for average fit, and .0005” per inch for light fit.

The smaller the diameter the harder it is to install/shrink and the closer the part is to finished size the less material to absorb the cold into it meaning it grows back to size at normal temp quicker.

Always good to have a plan for when the bushing gets stuck, because if you don’t have one (even if it is just beating it the rest of the way with a hammer) good chance you will have to machine it out and start from scratch.
 
I have chamber sleeved a couple of 16ga sxs to 20 ga.
I machine and file the outside of the sleeves to fit the 16ga chambers (machinist blue ink).
Inside is with a 20 ga reamer.
Extractors are the fiddliest, nuf said.
Sleeves held in by red Locktite.
 
oldstarfire said:
I have chamber sleeved a couple of 16ga sxs to 20 ga.
I machine and file the outside of the sleeves to fit the 16ga chambers (machinist blue ink).
Inside is with a 20 ga reamer.
Extractors are the fiddliest, nuf said.
Sleeves held in by red Locktite.
Click to expand...
A little different from what I’m doing (maintaining the same cartridge) but the concept is the same. Thanks. 👍
 
Licensed to kill said:
Turns out, chamber sleeving is something that is done for time to time so my thought is not too far fetched.
Click to expand...
Ltk, chamber sleeving is IMHO, definitely an option.

We aren't talking about super high pressures here.

If a C96 Mauser Broomhandle pistol upper can be resleeved to accept factory pressure cartridges, there isn't any reason it wouldn't be safe to make up similar sleeves for a SxS shotgun's chambers.

I'm not going to offer to do the job, but it's interesting. I have sleeved several 22lrs, 22 WMRs, and 30 M1 Carbine stubs to revive shot out bores, clean up chambers, or just to fit a tighter chamber to an otherwise good bore

Sweating in chambers is an easy option for a single barrel, but in the case of your SxS, there are many other issues to be dealt with.

I wouldn't try to separate the barrels from their block. I would look for a way to ream or drill out the chambers, make up a sleeve and use a high tensile epoxy, such as Titanium Putty, to take up the few thousandths clearance, to hold them in place.

I would ream the inserts before installing them. This would mean knowing the exact dimensions of the opening, and machining the insert to fit.

The next thing to figure out, is ream before machining the OD of the insert or doing it afterwards. Likely, I would ream a chamber in a steel cylinder, then machine the cylinder to fit the hole.

One thing to think about is the present chamber has cut outs for the cartridge rims. I would use the outside diameter of that to determine sleeve wall thickness. This will make a lot of things much easier later on, such as extractor slots, and would make the repair almost invisible.

Then, you would also have to make up a mandrel to insert into the sleeve, to keep it aligned properly with the axis of the bore of your barrels.

Much more to it, but IMHO, your biggest problem would be getting a drill bit or reamer matching the diameter you need.

I haven't looked online, but someone may even be making up the inserts you need already, and all you need are the right reamers/drills.

You may even be able to adapt choke tubes, not likely, but something along those lines, without threads.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom