Found a great deal on a Sheridan

[Van]

  I was right about the hard white PTFE check seals in the Mac1 kit.  It can take a day or so, stored under pressure, to set to the seat.  It suddenly stopped raising the pump arm so fast between strokes.  It was trapping air between the pump cup and inlet.  I think it was leaking out the check seal to the pump tube.  Had to reset the adjustable piston to take up that head space.  Found .20cal. Benjamin Pellets at Cabellas and it shoots 662fps on 8 pumps.  That is more than my stock 392 shot with the same grain pellet,  I am satisfied with that and will leave that part of it alone now.  This gun is quickly becoming a favorite.  Have not shot groups yet, but its very accurate so far.

[19Sheridan57]

  You should be very happy with those results !
 3 pumps for plinking & targets, 5 for small game hunting, up to 8 for larger game or longer distance shots. With a pumper, there is no reason to work yourself to death pumping it to the maximum. Store it with 1-2 pumps left in it to keep the seals moist.

[avator]

Yep, and when accuracy wains.. give it couple drops of secret sauce. Remember... a little goes a long way. IIRC, brass barrels don't need alot of cleaning like others. Pull a few patches with WD.

[Dave S]

  I was right about the hard white PTFE check seals in the Mac1 kit.  It can take a day or so, stored under pressure, to set to the seat.  It suddenly stopped raising the pump arm so fast between strokes.  It was trapping air between the pump cup and inlet.  I think it was leaking out the check seal to the pump tube.  Had to reset the adjustable piston to take up that head space.  Found .20cal. Benjamin Pellets at Cabellas and it shoots 662fps on 8 pumps.  That is more than my stock 392 shot with the same grain pellet,  I am satisfied with that and will leave that part of it alone now.  This gun is quickly becoming a favorite.  Have not shot groups yet, but its very accurate so far.

Looks like you're in the ballpark regarding velocity. My Mac-1 Steroid 12 pump hits 687.4 fps with 10 pumps and 727.7 fps with 12 pumps using the standard 14.3 gr pellets.
Good job! dave

[Van]

  Thanks to all for the suggestions on restoring this old gun.  I have a Mac1 billet pump arm on my 392 that I started to swap onto the Sheridan but was afraid to try to remove the almost 50 year old pins. I thought they may rip the wood when they come out.  Instead I tried the Mellon Air bushings, not the pin, just the ring and bushing, on the original arm.  Its for a 1377 so the pin is a little short.  Made my own pins from tool steel. The bushings add a bit of strength and cut down side to side movement on the main pivot hole.  They fit fine on the Sheridan.  That with some Secret Sauce on it and the rivet should make them last a long time.  You can order just the ring and pivot bushing.  Works on the weaker 392 arm too. 

[19Sheridan57]

Don’t worry yourself about wearing a Sheridan out.  I have some that are original , still working, that are 50-60 years old !!

[Van]

  Yep.  May be a bit of overkill on a Sheridan but I just had some left over from 1377 builds.  They do more good on a 392 or 1377 which have the weaker pump arms.

[Van]

   Now that I got finished with everything, here is what I get with the Mac1 reseal kit:  4 pumps- 505fps,  6 pumps- 600fps,  8 pumps- 660fps,  10 pumps-  705fps  using Benjamin 14.3 pellets.   I think I will shoot 4 to 6 pumps most of the time unless hunting.    Looks like from 4 to 6 pumps has the largest gain in FPS.

[avator]

Well, as I'm sure you know by now.... they just don't build them like a good ole "Dan" anymore. A couple drops of 'sauce' every now and then and regular use and they will last virtually forever.
Like many, I don't really find the need to pump over 5. If the gun is not up to the task at hand, I simply go in the house and get one that is.