If you go from a 20" pencil upper with A2 stock to a 14.5" upper or even 11.5" upper, are there buffer or other changes needed or recommended (still on an A2 stock)?
Thanks

You shouldn't need too.

Personally I use adjustable gas blocks on all of my uppers and tune them for use with a H1 buffer so I don't have to swap out the buffer spring or buffer weight, just push two pins and drop on the next upper, fire until it gets to hot to hold and repeat.

i had to.....i went from a 11.5 to a 14.5 and it would not run on same same buffer and spring

11.5 BCM upper ---H2 w/ heavy spring
14.5  Colt SOCOM----H w/ standard spring

my 11.5 is even tuned down with an adjustable gas block

try it and see what happens...adjust it if it doesnt perform correctly

ive got a 8.5" .300 blackout upper to try out now.....im expecting to have to adjust/tune it also

Thanks Tony_K!