BSA Mercury

[Weasle]

After 50 odd years of being a confirmed air rifle nut...I have never taken a Mercury apart.
This one is from the early '70's and never been apart...I know the original owner who bought it new in 1972.
How much pre-load should I expect when unscrewing the trigger block....which is now....at last and with assistance free and revolving/unscrewing nicely.

BTW its sees to be suffering from a perished seal and buffer washer as it sticks quite horribly when trying to cock it.


Many thanks in advance from the learned members.

Cheers Steve

[ken69]

I stripped and resealed mine a couple of weeks ago. The buffer washer and breech seal had perished and the O ring had a piece missing (I suspect from being stuck to the cylinder bore as it hadn't been cocked for quite a few years). Pre load on disassembly was quite low, with a little pressure on the end block I was able to control it quite easily. Reassembly was a little more difficult as I didn't want to use a spring compressor in case I damaged the paint on the end block. I had to get my missus to hold the rifle upright with the barrel resting on a piece of carpet and use my considerable bulk to compress the spring and reattach the end block. Took me a couple of goes and a few sweary words to get the thread started but managed in the end

[Weasle]

I stripped and resealed mine a couple of weeks ago. The buffer washer and breech seal had perished and the O ring had a piece missing (I suspect from being stuck to the cylinder bore as it hadn't been cocked for quite a few years). Pre load on disassembly was quite low, with a little pressure on the end block I was able to control it quite easily. Reassembly was a little more difficult as I didn't want to use a spring compressor in case I damaged the paint on the end block. I had to get my missus to hold the rifle upright with the barrel resting on a piece of carpet and use my considerable bulk to compress the spring and reattach the end block. Took me a couple of goes and a few sweary words to get the thread started but managed in the end

Many thanks for this...I can see that I will have to have my H&S hat on.

Cheers Steve

[rovercoupe]

You can get a feel for how much pressure is in there by unscrewing it a couple of turns and lean on it, I put a pair of leather gloves on the end block and put the muzzle on a block of soft wood. You should be able to feel it move it the threads a slight amount when you have leaned on it enough and gives a good gauge as to how much pressure is in there. It’s normally harder to put it back together than getting apart.

[SRV1]

Hi Weasle, replied to your post of the same in the General Section.....

[piggy589]

Replacing the trigger block without a spring fitted can help in that you know where the two threads engage when under load