mag compatibility?
 

is there a list of ''compatible mag''?

for exemple, I have a couple of high capacity mag with my g36 and I would like to know with what modele i could use them.

Normally G36 mags only fit on other G36 type (G36k,G36e...). Tif my memory is correct it's an unique mag they use, not like the M4 that use STANAG and work on SCAR, HK416, TAR-21, etc.

There is a M4/16 Magazine well adapter for the G36 Series looked kinda cool

just g36's and most brands will work.
m4 m16 416 scar l tAR 21 PDRC fn fnc and a few others use the same mags

While we're here (sorry for thread hijacking if I'm doing so) how reliable are the G36 to M4 mag well conversion kits?

Not very reliable.
I heard the combination of centain brands will work better, but my TM G36C and UFC mag well conversion kits works terrible together. After some sanding and modification it is now acceptable, but still have issues when its cold.