Help with a BSA 240 Magnum

[fullmetaljacket]

I recently acquired a BSA 240 Magnum in 0.177", mostly for sentimental reasons, and I have some questions for those with more experience with this model.



The cocking lever cannot be closed until it is parallel with the frame.



The gap is quite obvious here.



The culprit seems to be the breech seal, is this the standard item or is it oversized or incorrectly installed?



The previous owner manufactured his own lever catch since the standard ones he replaced kept being broken, is this a common issue or a problem with the catch being forced against an non-standard/incorrectly mounted breech seal?



The safety catch doesn't stay locked reliably in the "fire" position once the pistol is cocked, again could this be due to the incomplete closing of the cocking lever or is it a separate issue?

Any help is appreciated!

[brucieboy]

First thing I'd do is remove the breech seal and then see how it closes.The seals are a real pain I've found and often need experimenting with.The mk1 and mk2 seals are different I believe.

[ChrisGerr]

I'll have a look at mine later and send you some pics if I get the chance. Looks like you have a late model MK2 and the problem may very well be the breech seal because both mk2 bits (o ring and plastic spacer) are like hens teeth to find. It may very well be the previous owner sourced an o ring that is too thick and might cause this issue.

Think I have some spare if that's the problem and will post them if needed.

Chris

[fullmetaljacket]

Thank you guys for chiming in.

First thing I'd do is remove the breech seal and then see how it closes.The seals are a real pain I've found and often need experimenting with.

I removed the seal and it certainly seemed to close better if forced.

The mk1 and mk2 seals are different I believe.

Ah, that raises and interesting question... how does one tell the difference?

I'll have a look at mine later and send you some pics if I get the chance. Looks like you have a late model MK2 and the problem may very well be the breech seal because both mk2 bits (o ring and plastic spacer) are like hens teeth to find. It may very well be the previous owner sourced an o ring that is too thick and might cause this issue.

The o-ring it came with certainly looks oversized, however I tried replacing it with some smaller ones and they didn't seal at all, the pellet barely moved in the barrel. I think there must be something else that's preventing it from closing completely.

With regards to the safety button issue, I presume it engages when the piston is cocked and has nothing to do with the lever being closed, since I was unable to find anything that would be linked.

Think I have some spare if that's the problem and will post them if needed.

That would be very kind, thank you Chris!