So I am finishing my RPK build - my first I did on my own, and I am now replacing the original gas piston with a TAPCO USA part.

I noticed that the TAPCO unit is slightly shorter than the original commie gas piston - maybe 1/4"?

Does this matter at all? I went ahead and pinned the new one on, following the instructions to unthread it a 1/2 turn or so to produce a little wobble. New unit assembled is just a little shorter than before.

Does this matter or am I just being too worried about it?

David.

I don't think it matters. Shoot it and see for yourself.  

It might shoot softer then usual, if you happen to stovepipe or other fte, that's a reason why

It might shoot softer then usual, so if you happen to stovepipe or other ftf/fte, that's the reason why. Because your piston has now shorter stroke. On the other hand  it might also be good for you , if your weapon is overgassed like majority of Ak

Tapco AK pistons came in a AKM and AK74 length with a spacer to use in one of them...could this be a similar situation but missing the spacer?