D48 piston and breech seal

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mcoulter

mcoulter

Member
Dec 16, 2015
1,190
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Syracuse, NY, USA
To make a long story short, I learned a TON regarding my 48 since the piston and rod separated. Hats off to Umarex for replacing the piston for me. I also got added in an extra piston seal and breech seal.

But let me me tell you that replacing the breech seal in the compression tube was a ROYAL pain in the butt! Even with the compression tube removed there was NO picking, prying, plucking, scraping, or convincing that bugger to get out. (It was pretty ragged looking so that's why I wanted it out of there.) I eventually had to put a torch to the compression tube and after a few minutes of heading it, the old breech seal DID come out.

If you have a 48 and ever plan to replace this breech seal plan on removing the compression tube and doing the same. :)
 
from John Steward on rebuilding a 48..
To replace the breech seal, use a quarter inch diameter drill bit and insert it into a drill, then stick it into the opening of the breech seal. Slowly drill it just slightly into the breech seal. Not too far or you can damage the air vent hole! You can now pull on the drill and you should be able to pull the seal out. Another method I like even better - use a nut driver (like a screwdriver with a head that holds a nut or in this case the hex head of a one quarter inch, several inch long lag bolt). Screw a lag bolt into the breech seal, then pull on the lag bolt and the seal should come loose. You can also use a dental pick like instrument, but trust me, the breech seal is hard to get out and requires more muscle than you can exert with a dental pick. Install the new seal by using a 3/8ths inch diameter wooden dowel to gently tap it down into place. Make sure the cupped side of the seal faces out, the flat side down. If your gun has had velocity variations and shifting POI, the culprit can be a burned or damaged breech seal. On one new 54 I had at one time, it was all mangled - a large bur on the end of the breech end of the barrel was cutting it to ribbons, and the gun's velocity was therefore very irregular. 
 
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