its a gen 3 thanks for the info

I just got my first Glock a mod 20. I bought  a 51/2 inch barrel and a 22 lb. spring. When I ordered my barrel I asked if I should use a buffer and they said not to. Just looking for opinions and also I noticed that there are no high cap. mags for the 10mm.
Will the high cap. mag for the 40 work. Am a new member here and looking to get educated on the glock 20. plan on using the 180 200 grain underwood and Buffalo Bore ammo.