Question for an expert gunsmith.

[Mosti]

Can a gun which has a 65mm chamber be bored expertly a further 5mm to suit 70mm cartridges??
The specific gun is an english sbs, ejector boxlock with damascus barrels which are nitro proofed.

Regards.

[Mike George]

I am not a gunsmith, but I'd guess that it depends on the thickness of the walls in the area currently occupied by the forcing cones. The only way you would really find out is to take the gun to a professional for an opinion. The gun would have to be re-proofed after the work was complete. Just noticed that you live in Malta, where presumably UK proof rules don't apply, but there might be local legislation. My own, unqualified, opinion is that, as the barrels are Damascus, it wouldn't be worth the risk of ruining what sounds like a very nice gun.

[normanb]

It will depend on the gun ,its age and overall condition . It will also depend on what you intend to shoot through it . If taking into account that you have no proof laws that I know about ,if it is for the purpose of using 70 mm cases because of the difficulty of obtaining 65mm cartridges and you will be shooting the same 30 gm loads then there should be no real problem .If you want to shoot heavier 36gm loads then it really needs an experienced man to look at it first .
As the current C I P proof pressures are the same for 65 & 70 mm chambers I now submit all reproofs and sleeved guns at 70mm . To date I have had no problems although I do not advise customers to use heavy loads constantly
Do not forget it is the additional strain on the action and lever work that is and must always be taken into consideration . In short ,yes it can be done but you must accept responsibility for any failure or detriment of the gun after such work is done.

[ROBERT6500]

A slightly different point of view from me but that old gun sounds lovely and I would personally leave it original which is why most people buy those guns, to do just that.
If I wanted a 70mm chamber or bigger then I would buy another gun with them as standard.

[Mosti]

Thanks for the replies. I think I will leave it as it is.

Regards.