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

[look no hands]

There could be quite a lot, I normally sit on the floor put a pile of old shirts or something in between my legs, I then put the trigger block in the clothes and then with thick gloves on unscrew the cylinder so when the cylinder and trigger block separate the block and spring get contained in the clothes.

Hopefully that helps.

Pete

[Weasle]

There could be quite a lot, I normally sit on the floor put a pile of old shirts or something in between my legs, I then put the trigger block in the clothes and then with thick gloves on unscrew the cylinder so when the cylinder and trigger block separate the block and spring get contained in the clothes.

Hopefully that helps.

Pete

Hi Pete

Many thanks for that.....I'll be careful. 😎

Cheers Steve

[Phil Russell]

Have a look at the Idiots Guide in Collectables ... posts 37, 38 and 122 for the Mercury.
If you have a vice it can be useful to either clamp the trigger block in the padded vice and unscrew the action from the block or clamp the action and unscrew the block. I advise wearing a leather glove just in case and put a towel over the action as you unscrew.
When you come to reseal etc, a Meteor O ring BS210 can be better than the normal Mercury one (BS212). If you want to make a new buffer washer, a tap washer works or some thick leather.
Cheers, Phil

[STR8SHOOT3R]

I did one a few years back and there was a fair bit of preload. Per the above, I pressed the action down on a pile of rags and unscrewed the end block while wearing thick gloves.

Try to put as much bodyweight on it as possible while unscrewing the trigger block. Good luck!

[TonyL]

Easier if you remove the barrel, too, giving a shorter, sturdier "piece" to work with and no chance of the barrel "breaking" open.

[SRV1]

Hi Weasle,

As per advice above when removing the trigger block, I made a tool to fit my spring compressor that does the job for me.

Two years ago, I acquired a very good condition early Mercury 0.22 that had seen little use, difficult cocking as per yours. Took quite an effort to remove the stuck swollen nylon piston head, buffer and debris. Cylinder good - no damaged internals. I replaced head with an alloy one, Meteor "o" ring, new buffer, de-burr, spring good, just polished ends, good clean-up and correctly lubricated and now she is a good 'un doing about 10.4. Have fun and enjoy.

[Weasle]

Have a look at the Idiots Guide in Collectables ... posts 37, 38 and 122 for the Mercury.
If you have a vice it can be useful to either clamp the trigger block in the padded vice and unscrew the action from the block or clamp the action and unscrew the block. I advise wearing a leather glove just in case and put a towel over the action as you unscrew.
When you come to reseal etc, a Meteor O ring BS210 can be better than the normal Mercury one (BS212). If you want to make a new buffer washer, a tap washer works or some thick leather.
Cheers, Phil

Many thanks Phil

[Weasle]

I did one a few years back and there was a fair bit of preload. Per the above, I pressed the action down on a pile of rags and unscrewed the end block while wearing thick gloves.

Try to put as much bodyweight on it as possible while unscrewing the trigger block. Good luck!

Many thanks.....I'll be careful...very careful

[Weasle]

Easier if you remove the barrel, too, giving a shorter, sturdier "piece" to work with and no chance of the barrel "breaking" open.

Cheers Tony...that sounds like a great idea....I'll do a report on how it goes....

[Weasle]

Hi Weasle,

As per advice above when removing the trigger block, I made a tool to fit my spring compressor that does the job for me.

Two years ago, I acquired a very good condition early Mercury 0.22 that had seen little use, difficult cocking as per yours. Took quite an effort to remove the stuck swollen nylon piston head, buffer and debris. Cylinder good - no damaged internals. I replaced head with an alloy one, Meteor "o" ring, new buffer, de-burr, spring good, just polished ends, good clean-up and correctly lubricated and now she is a good 'un doing about 10.4. Have fun and enjoy.

I am planning to fit an alloy head if it's got a nylon one fitted.
Again thanks for the great advice.
Cheers Steve

[charliemow13]

I've recently finished refurbishing a mk1 Mercury with some excellent feedback and advice provided by various members in the collectable section of the forum. I put on an alloy piston head and also added a guide and top hat (chambers I think) together with a piston sleeve made in 0.004" ( 263934584802) and a couple of shim washers at the front of the spring between the spring and sleeve ( 132407910887) although you'd obviously have to check sizes on both to see if they were right for you. Link to piccies below of preload that there is in my example with a new "standard" chambers spring.

Best tip I had for getting it all back together was from T20 which was to check at what point the threads on the back block and the compression tube engage without the spring in. Then when it comes to compressing the spring and trying to screw the two parts together at the same time you'll be able to roughly line them up and have a better chance of getting them engaged quickly. Makes it so much easier.

http://imgur.com/a/j8To8vb

[TonyL]

I am planning to fit an alloy head if it's got a nylon one fitted.
Again thanks for the great advice.
Cheers Steve

The buffer is also liable to degrade and bulge over time, Steve. Some people re-build without the buffer, drilling a hole further back down the piston rod "peg", relocating the piston head and giving more stroke. I think some have said that they had to relieve the cocking slot at the rear of the piston to give the necessary clearance on the cocking lever.

There will be some posts on the subject on here if interested in pursuing this route. Also some information / parts on the TRRobb site.

[Weasle]

The buffer is also liable to degrade and bulge over time, Steve. Some people re-build without the buffer, drilling a hole further back down the piston rod "peg", relocating the piston head and giving more stroke. I think some have said that they had to relieve the cocking slot at the rear of the piston to give the necessary clearance on the cocking lever.

There will be some posts on the subject on here if interested in pursuing this route. Also some information / parts on the TRRobb site.

Many thanks Tony

[look no hands]

The buffer is also liable to degrade and bulge over time, Steve. Some people re-build without the buffer, drilling a hole further back down the piston rod "peg", relocating the piston head and giving more stroke. I think some have said that they had to relieve the cocking slot at the rear of the piston to give the necessary clearance on the cocking lever.

There will be some posts on the subject on here if interested in pursuing this route. Also some information / parts on the TRRobb site.

I've done the above long stroke to one of mine but all I gained was about half a foot pound, you might be lucky and get a full foot pound extra.

Pete