doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com How much metal is bored out when sleeving bbls?

Lads
I have sometimes wondered how much metal ( % wise) is bored out of the chamber stubs to accept the reduced diameter of the new bbl to be put on...would anyone who does this, or knows,please tell?
Is it like %50 old metal & %50 new when looking down the chambers of a sleeved guns bbls?..or more original wall than new bbl, or what?
thanks
Franc

Hey Franc, when looking down the tubes you see the complete new sleeving tube as this has gone into the old breach ends. 100% new metal.

Cheers
J-PD

If I am reading your question correctly, you are asking how much are the remaining breech stubs are bored out to accept the new sleeves? I hope someone chimes in with an answer, it is something I am curious about as well.

I always wondered how much the step down in the new sleeve (where it enters the old breech stubs) weakened the sleeves, since that step takes place right in front of the chambers. Is there a different proofing requirement for sleeved barrels?

Yes flintfan,
That's what I mean.Actually I think its not in front of the chambers...but that that those turned down inserts run from just ahead o the chamber right down to the shell rim cut at the breach end...the shell rim must have to be re cut , as its either partially or totally gone because of the boring job...and you will have a least some unfinished bit of the new tubes stopping flush with the end of the original chamber wall....right....????
Or put another way...how thick in the wall is the reduced insert part of the new bbls,in a percentage of the finished breach end chamber wall???
Know what I mean?
Cheers, franc

The chambers are opened up to the rim diameter then the new tubes are turned to suit.When the rims are re-cut it will just clean off the end of the sleeve.
I will take this opportunity to say to people that I dont think that welded sleeving is a good idea.In days gone by when the sleeve was tinned in,the full surface area of the join was attached to the remaining breech end.This effectively makes the area from the chamber to the outside of the breech end one piece.With the welded sleeving the join is only joined at the two welds(Two if the rim has been welded in aswell).This effectively leaves a gap between the sleeve and the remains of the original breech which is unsupported.It means that the join is much weaker than a fully tinned join and if a weld fails the tube could come out.

flint , yes, sorry , I see you what you mean mate
I wonder if in a well sleeved pair...one would consider it just as strong as original chamber walls..(don't know how tight the fit is)I've always kinda thought that they would be..but am just wondering.
I wonder would the insert wall crack or bulge if too thin & had a sloppy solder fit into the stubs?
John Foster, SKB ,Hugh Lomas??????,
Franc

Pugwash, you beat me to it...
cheers, I was wondering if it would be to the rim cut.
I thought by welded joint, they mean it was tinned full length & then kinda made invisible with a tig weld or something on the seam.
Lets hope they really force those tubes in good n hard eh?
thanks lads
Franc

Guys,
When barrels are sleeved(in Germany),they are drilled/reamed out from the rear to fit purchased barrel blanks, which are of such thickness throughout to withstand the proof pressures.The thickness of the walls of the old barrel stub (hakenstuck),then, would depend on the diameter of the original barrels.All the ones I saw were softsoldered in(the old barrel bundle would have been hardsoldered [brazed]at the breech end only),the joint being large enough that softsolder is sufficient.If my memory is not too bad, the diameter of the barrel blanks in 16 ga are either 18 or 19mm at the chamber end.
Mike

On reflection,I think the 18 or 19 mm is the dia at the shank of the rifle barrel in a drilling,rather than 16 ga barrel.
Mike

Why do you say this? How do you know this? How much strength is needed? What are the forces involved?

I say this because the welded joint leaves a large area of of the join effectively flapping about.I know this because I have seen how a sleeved tube has blown into a cutter mark that was left when reaming out the original chambers.The soldered joint offers a much larger surface area for the tube to be attached to the existing breech end.A good part of the force from the cartridge when fired is directed outwards against the chamber wall.If the chamber wall is not attached to very much it has the potential to move around especially if it is only welded at one end.The tinned joint means the tube and the breech end are fully attached as if they were one piece.