I was wondering if some one could explain the difference between these two and the pros/cons of them?
As I understand it, it is the distance traveled by the piston itself. Short stroke is obviously the better system as the cycle time will be a bit quicker. I'm not sure about a long stroke being less felt recoil?
Not too many have used a long stoke system, IIRC?
Short stroke piston is where the piston is not attached to the bolt carrier a la FAL, SKS.
Pros - piston and bolt/carrier return at different times in the cycle - spread return to battery impingement forces out
Cons - piston has its own spring which is exposed to/closer to the heat source, weakens with excessive heat and fails sooner. Modern materials have overcome this and is typically not an issue with semi autos. Less mass to assist in case extraction.
Long stroke is where the piston is attached to the bolt carrier a la AK and its ubiquitous variants.
Pros - more reciprocating mass assists in case extraction, typically lower rate of fire - more controllable.
Cons - more return to battery impingement forces.
In both you have a significant reciprocating mass not in the same plane as the barrel which will affect accuracy. Unlike the AR with only the gas key out of plane.