General breech seal question

[vbull]

In general are breech seals on most rifles just ordinary O-rings or are they something special ? I've just received a replacement breech seal for a Walther LG55 and to me it appears to be just an O-ring, the type you can buy in bulk, assorted sizes on that auction site or should they be made of a special rubber/composite material or something ? The one I took out of the gun was hard and flat so I'm wondering if they become like this with use but started out just plain O-rings. Thanks.

[Benelli B76]

Bob, there are a variety of materials used, as you know leather in the Jurassic period and now rubber (nitrile and viton) normally black, and polyurethane in a range of colour dyes, white, green, blue etc. Modern manufacturers use polyurethane as it is tough and tear proof and very resilient (has a good memory). I tend to use polyurethane in tube shape and O rings, sometimes glued 2 together to get the correct depth. I tend to use the tube shape cut on my lathe when there are two dimensions in the depth of the recess for instance on the BSA Cadet.

regards, Baz

[PhatMan]

vbull,

Storing the rifle with the barrel broken will lengthen the life of the breach seal.

The 'flat' appearance of the old seal was possibly due to it being stored compressed.

My ca. 1974 Diana (Original) 35 still has its original seal in fine condition, and has always been stored with the barrel broken.

Have fun & a good weekend

Best regards

Russ

[vbull]

Thanks for the replies. I guess I should experiment a bit as I've got a lathe. Baz, where do you get your Poly from ?

[Benelli B76]

Thanks for the replies. I guess I should experiment a bit as I've got a lathe. Baz, where do you get your Poly from ?

Bob, get off the evil bay. Funny, as we are discussing it a piece just arrived 300mm x 25mm 90 degree Shore hardness. It can be expensive (24.99) but you get a lot of bits out of it including piston seals. I buy different diameters depending on the job I am doing.

Baz

[vbull]

Just bought some Baz but couldn't find any with a mention of shore hardness, 200 mm for £6, I suppose I've bought the wrong stuff judging from the price difference ? Could you give me an item number ?

[DCL_dave]

Just bought some Baz but couldn't find any with a mention of shore hardness, 200 mm for £6, I suppose I've bought the wrong stuff judging from the price difference ? Could you give me an item number ?

Could try these people: https://www.directplastics.co.uk/polyurethane-rod

I have ordered a few bits from them, happy with their prices and service.

[Benelli B76]

Just bought some Baz but couldn't find any with a mention of shore hardness, 200 mm for £6, I suppose I've bought the wrong stuff judging from the price difference ? Could you give me an item number ?

Bob, you can try the one you have ordered could be ok for breach seals. You do not mention the diameter. To cut breach seals you can make up core cutters from steel tube to the diameters you want, as you do not turn them with normal lathe tools as they are small. To part them off you can use a medical scalpel. As I said previously if the seal seat in the rifle barrel is a uniform depth rather use O rings as it is quicker and easier. If Dave is coming over to you again I can meet him at Brothers and explain before he sees you.

Baz

[vbull]

Thanks for the link Dave, spoilt for choice there. Baz, I'll take you up on your offer, will be seeing Dave soon.

[Benelli B76]

Bob, had to make core cutters for a new size seal for CO2 pistol so I thought I would upload pics. You can make breach seals the same method and part them off with a scalpel a la Lawrie method.

Baz

[Phil Russell]

Spurred on by this thread I got myself a metre of polyurethane tubing 12mm od, 8mm id from the bay for about £3 .... 12mm / 8mm is a common size for several old rifles so I will see how it performs when I need some .
Cheers, Phil

[vbull]

Thanks Baz, maybe if your coming this way you could pop in and show me the stuff you use and maybe help me out on the lathe.