BSA Cadet Breech Seal

[Yeoman]

Just bought a replacement leather breech seal & would like to know if it has to be trimmed to the breech face angle once fitted, also what should it be lubricated with ?
Thanks
Greg

[air revolution]

hi greg,i cant figure why a leather washer when ptfe is available and in my opinion better.back to the question-trim the washer on the angle and i always used neatsfoot oil to lubricate.in future give terry robb a bell he can supply ptfe breech and piston seals,they work. regards nik

[edbear2]

HI.......I have done a couple of these (and messed up one)....what I personally found to work (as with everything, there are different ways to go about it)...I put a very slight chamfer on the leading edge of the seal to aid insertion, and reduced the O.D. slightly, as it was very oversized (note;....do all this dry or you will never get it in!!)....then carefully tapped it in till seated. I then used a new stanley blade to carefully trim it flush with the breech face....then, as posted previously, applied a few drops of neatsfoot, or green oil. This has the effect of swelling the seal slightly, ensuring a tight fit, and makes it expand slightly away from the breech face to provide the sealing effect. I have heard all sorts of ways, including using lard/tallow et al., but the way described above worked for me

[Rob M]

It probably will need to be trimmed, with a sharp blade like a scalpel, so that it's about .5 of a milimitre proud. I like to lubricate my leather seals with Abbey SM50, it's molybdenum in silicone oil, it preserves the leather better than mineral oil, and while people always used to use Neatsfoot oil for softening leather I have doubts about it as the neatsfoot oil I bought a few years ago seems to have some water or moisture as well as miscellaneous bits of foreign matter in it, things that look like fish scales for instance.

If you do decide to use SM50 or some other silicone based product you must ensure that you don't use so much of it that it can spread into areas of metal to metal contact where it will cause accelerated wear, I soak leather washers and seals in sm50 for a few days but then take it out and leave it a day or two more to allow it to absorb any left on the surface, then dry as much as possible with kitchen roll or dry cloth so that there is little or no silicone on the surface of the leather. The silicone in the leather should prevent it absorbing mineral gun oil and disintegrating in a few years time, that's my theory anyway! I have seen oily old leather seals and piston heads falling to bits like wet cardboard, some oils cause the leather to literally disintegrate after a while.

Don't use PTFE, it conforms to fit wherever it's used, so after a while will not provide a good seal. It can be good for piston heads where the bore is parallel, but isn't good for breech seals on older guns in my experience.

Ed's advice is good, but if you aren't sure if the Neatsfoot oil you can get is the pukka stuff from the olden days I would give it a miss, as I am certain that the Neatsfoot Oil on sale in some places isn't the proper, old-fashioned stuff, and my suspicion is that it can promote rust.

[I. J.]

Or cheat!
I replaced the awkward to fit, angled breech seals on a couple of BSFs of mine by using one and a half neoprene 'O' rings.

ATB
Ian

[Yeoman]

Thanks for all the replies they are most helpfull, as for a PTFE breech seal, I didn't know they were available before the leather one arrived. As I've got Abbey SM50 I'll give that ago.
ATB
Greg

[Phil Russell]

I have made angled, deep breech seals from poly or silicon tubing. Works fine if you can match the inside and outside diameters to the breech seal measurements.
fit and then cut slightly proud with a very sharp blade.
Cheers, Phil

[I. J.]

I have made angled, deep breech seals from poly or silicon tubing. Works fine if you can match the inside and outside diameters to the breech seal measurements.
fit and then cut slightly proud with a very sharp blade.
Cheers, Phil

Good idea. I spent ages sorting through my various sized 'O' rings to find 2 (well, one and a half ) that would fit.

ATB
Ian

[franktheferret]

Most older BSA rifles will take the Supersport/Lightning breech washer, as long as the old leather seal is removed completely.

That is when you discover that the breech face is not perpendicular to the bore! You can then shut the barrel a few times and trim off the offending bits at the bottom of the breech with a scalpel.

It works.

There is a higher-precision way of doing this, but it is much more complicated, and needs two of the newer breach seals to start with, as well as a very good eye.

Good luck,

Alan.