From: none@none.com99   
      
   On 5/10/2025 3:53 PM, Bob La Londe wrote:   
   > On 5/10/2025 3:24 PM, Snag wrote:   
   >>    Today at the yard sale I picked up a Crosman "American Classic"   
   >> model 1377 for ten bucks . It doesn't pump , and I think it's probably   
   >> the cup on the pump . Part is available for a few bucks and I'm   
   >> wondering if I should replace the rest of the seals and o-rings too .   
   >> Is there anything in there that I wouldn't have in a box of assorted   
   >> o-rings ? I've also seen "big bore" sleeves for the barrel/pump   
   >> connection , looks like something an enterprising old fart with a   
   >> machine shop could duplicate ...   
   >>    BTW , this pistol has the rotating sleeve instead of a bolt , cocks   
   >> by pulling on a knob on the back end of the pump sleeve . I have no   
   >> idea how old it is but it doesn't look exactly like the current model .   
   >   
   > I resealed a 1st generation Model 1 in .22 I think they use the same   
   > plenum and knock valve.  My son might have his grandads 1377.  Hold on.   
   > Let me go look in his gun safe.  I think they all have similar internals.   
   >   
   > Would you have the seals?  Its been a while since I had my Model 1   
   > apart.  I don't recall.  I seem to think there might have been something   
   > different, but its not hard to take apart and look.  I think there are   
   > even some videos on YouTube doing it.  Got a cup with a lid or a zip   
   > lock bag to keep things in?  Take it apart and look.   
   >   
   > Yes, you should replace the seals and o-rings.   
   >   
   > The cup is probably bad, but probably so are the seals on the plenum and   
   > knock valve.  Works just like a PCP except it has a tiny little air   
   > reservoir.  A spring loaded "hammer" slams into a pin opening the air   
   > valve and dumping air into the barrel.   
   >   
   >  >> I've also seen "big bore" sleeves for the barrel/pump connection ,   
   >  >> looks like something an enterprising old fart with a machine shop   
   >  >> could duplicate ...   
   >   
   > I have not seen that, but you absolutely could.  Things have to have as   
   > good of a finish as a hydraulic cylinder, but its possible.   
   >   
   > The problem with a large volume pump is that I don't think you gain any   
   > power after a certain point.  Instead the air valve closes again without   
   > releasing all the air.  In fact you can potentially get less power if   
   > you over pressure the plenum because its harder for the hammer to open   
   > the valve.  That's kind of how an unregulated PCP works in fact.  By   
   > taking advantage of that principle.  Anyway if you have the arm strength   
   > to spare it might pump to optimum charge with fewer pumps.  Or maybe I   
   > don't know what you are referring to.   
   >   
   > You can get more power out of a multi pump pneumatic if you increase the   
   > strength of the hammer spring and/or enlarge the plenum.  Then more   
   > pumps or larger pump "might" be give more usable power as long as the   
   > plenum will hold it.   
   >   
   > I just looked.  The one my son got from his grandad is a 2100, but I   
   > think they have almost the same guts.   
   >   
   >   
      
   OH! DUH! Pistol. LOL. Sorry if some of my comments don't quite match up.   
   The principles are all the same.   
      
   --   
   Bob La Londe   
   CNC Molds N Stuff   
      
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