My Pleasure towle...
You have no need to worry about differing head space, the piston chamber and piston are exactly the same as they have always been. They just messed up the breech sealing. Its a good idea going to a simple O ring, because they are so cheap and reliable, but they forgot about the slight angle on the face of the valve housing. An O ring does not flex enough to take up the angle. It required more of a thicker, rubbery seal. Taking the measurement of the angle across the front face of the valve block (where the TP hole is) I calculated across the width of the O ring seal, that there is 0.1mm of squeeze on the top face but -0.1mm (zero squeeze) at the base of the O ring.
For anyone else designing a seal for an O ring, O rings seal by way of a perfectly flat face coming into contact with the O ring face, with a minimal contact. If a face meets your O ring at a slight angle, or too much squeeze, the O ring will distort and not seal. O rings have zero shift to take up error and require very critical tolerances to function correctly. Remember the breech seal of the BSA Magnum pistol. An angled breech coming into contact with a square TP black. It used a big pliable rubber washer.
I mailed Chiappa firearms regarding this massive error (in reg of their own reputation and to provide us with a correct off the shelf spare seal) but there reply was the seal was adequate....It really is not!
You have no need to worry about differing head space, the piston chamber and piston are exactly the same as they have always been. They just messed up the breech sealing. Its a good idea going to a simple O ring, because they are so cheap and reliable, but they forgot about the slight angle on the face of the valve housing. An O ring does not flex enough to take up the angle. It required more of a thicker, rubbery seal. Taking the measurement of the angle across the front face of the valve block (where the TP hole is) I calculated across the width of the O ring seal, that there is 0.1mm of squeeze on the top face but -0.1mm (zero squeeze) at the base of the O ring.
For anyone else designing a seal for an O ring, O rings seal by way of a perfectly flat face coming into contact with the O ring face, with a minimal contact. If a face meets your O ring at a slight angle, or too much squeeze, the O ring will distort and not seal. O rings have zero shift to take up error and require very critical tolerances to function correctly. Remember the breech seal of the BSA Magnum pistol. An angled breech coming into contact with a square TP black. It used a big pliable rubber washer.
I mailed Chiappa firearms regarding this massive error (in reg of their own reputation and to provide us with a correct off the shelf spare seal) but there reply was the seal was adequate....It really is not!
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