re: nitro piston fitting

[patent1]

Hi all, I have a Benjamin Prowler (B18/19) that I am rebarreling from a .22 to a .177.  The question I have is which way does the nitro piston work best? It will fit either with the body of the NP in the piston or the ram in the piston.  With the body of the NP in the piston it seems that it would have more mass to better shoot a heavier pellet, but initially would take off slower.  With the ram in the piston the piston would take off quicker because of less mass to move and compress air faster.  And would a preload washer help with a gas ram? I have already swapped the seal for a Vortek moly impregnated seal and buttoned the piston, there is not much else to do with a gas ram other than wrap it with plastic to keep it centered wherever it is mounted.   

[mobilehomer]

If you find the balance point of the ram, it might surprise you. The shaft end is actually heavier by just a little. With the body in the piston you also eliminate an area of friction, because the body stays in the piston instead of moving back and forth. You may need to add a shim to maintain preload of about 3/8" for the end cap.

[patent1]

I don't understand what you mean by "With the body in the piston you also eliminate an area of friction, because the body stays in the piston instead of moving back and forth.".  If the body is in the piston it would have to move back and forth. With the ram in the piston, the body is stationary.  It also would seem that there is less wear and tear on the gas spring in general if it is stationary and not being slammed every time the rifle is shot.  In the parts breakdowns of the Prowler I have seen online, the ram is depicted as mounted both ways.  I am just trying to get some reasoning whether one way may be better than the other. 

[Roadworthy]

Originally the body of the gas strut was toward the rear having only the rod facing forward.  One of the manufacturers claimed a breakthrough bu flipping the strut and putting the body into the piston.  Crosman followed suit.  I don't know that anything was really accomplished.  I'm sure you'll find pros and cons for both methods.  You seem to understand the idea of more or less weight in the piston.  It may be a personal preference thing more than anything else.  There appears to be no right or wrong way to do it.  Me?  I'm back to a coiled steel spring.  It works about the same either way I install it.

[mobilehomer]

If the body is to the rear, every time it is fired, the body moves in and out of the piston. Reverse the ram so that the body is in the piston you remove one area of friction. The shaft is also just a little heavier.