new gun right? the rear breach seal is leaking. i put my hand over the breach and i can feel the puff of air when i fire. the seal recepticle is not very deep and these seals are maybe a 16th inch thick, unlike HW seals which are
about 3/16 thick.i don't even think there is enough dept for a shim.
anything i can get that is a little stronger and maybe a little thicker?
There is a delicate line to walk here. If you space them out too thick, the loading port doesn't close completely and it can pop open during the shot. I use a dab of glue under both seals when I need spacing.
PS - If you start fooling with the seals, you might want a pack of these (Courtesy of Russ57): A square cut o-ring with a 3/8" OD, 1/4" ID, 1/16" thick is a standard sized part. It is called a 010 size square cut ring. You can verify at McMaster Carr, part# 4061T115. 100 at your door go for the price of 2 + shipping from RWS.
it is beyond comprehension that the seal in a brand new gun is defective. they don't even fit tight in the pocket. when i touch it it moves. i popped it out with my fingernail. when i replaced the seal in my HW with a maccari breach seal i had to use a pick to pry the old one out. it was tight. this gun was badly designed from several angles. the seal itself does not show damage or signs of burning. it looks perfect. its just loose. i wonder if they shrink over time. it is synthetic so i would not think so.
OK, i went by Ace Hardware t his morning and aguired a few
January 22 2009, 10:43 AM
#5 o rings. round. they fit snug. i test fired. there is still a small "puff"
coming from the breach but not near what it was. that is still not as good as it could be. maybe a thin shim. some guys use dental floss for shim. i may give it a try. the #5 ring stands above the surface of the breach like a real
seal. not a lot but more than the original. the breach still latches with a "click". i did not do the front seal.
the way this breach should have been designed is with a larger seal like the
HW seal. its much bigger. a cam type lock should have been used instead of a
spring latch. my HW seal does not leak at all. no "puff".
I had three out of four 46's with good breech seals. The 4th kept blowing open the breech. Finally I replaced it with a new one and no problems after that........
on the breach block with another #5 o ring. these o rings stand above the surface maybe 1/64 (or maybe 1/128 ) higher than the original seals. they are also somewhat more flexible or compressible. makes a better seal. by changing the front one as well it takes up some small slack in the pivot bolt and that makes the REAR seal tighter as long as the latch mechnism is healthy and latching tightly.
ths time i get no "puff". not sure how long this will last with standard O rings. i guess they are neoprense as opposed to some other tougher material.
until i have something better i will just replace them as a matter of routine after every tin of pellets like doing scheduled maintenance. the o rings are cheap.
O-Rings and ring seals do not seal by mechanical pressure. They seal using the AIR PRESSURE behind them.
Certain looseness, especially in the ID is, sometimes, helpful.
I have used shims cut from Cell-o-Phane tape with the glued face down, so that the seal can move a little in it's pocket but still is a little "proud".
Again, the "proudness" is not what seals. It's the air pressure between seal and pockets what seals the cavity.
What you are describing is a basic pressurized sealing technique. When a tire shop inflates a tubeless tire, they put a band around it to move the bead to the rim all the way around. This forms an initial seal. Without the initial seal, the air won't inflate the tire. Relative to air rifle seals, the same is true; you need a good enough seal for the burst of air to seal; not good enough, no inflated seal. So even though the high pressure air forms the tight seal, the initial seal has to be good enough!