Improved model D

[slow_runner]

I was offered an old BSA model D the other week.
I was given a run down on it; no trigger, trigger guard or spring/s; it is all complete otherwise
A few images were sent.
Earlier this week it arrived and was unwrapped with some enthusiasm, my first real BSA.

Damn these old BSA's look good, feel good and they come up to aim very nicely too.

First appearances it seems to be in much better nick than I had expected, lovely. Going over it, a bit loose at the stock, some bruising marks on the wood but nothing that stands out except.....
The receiver is loose at the barrel joint, also there is some swelling of the receiver...
that obvious fact wasn't mentioned.
I separated it today and before looking too hard at the receiver (I was hoping for some good news first) I ran some cleaning wads down the bore with a length of brazing rod.
The rifling helix could be felt, so thats good news. I ran a few more and checked the bore; very clean.
I pushed a few pellets down and they moved nicely until the last 3 inches where they felt looser but not excessively so.
Onto the cylinder to check it out a bit closer.
Sitting in front of the piston head, a lump of what looks to be lead (solder?) fell into my hands.
Out with the internal calipers and vernier. The ID measures 38mm and just behind the thread the ID is 38.5 or thereabouts.
Sourcing spares don't look half as bad a problem now as this revelation.
My first thoughts are, "bugger, this looks bad....what to do?"

I will get the camera out and post some images tomorrow.