This is my first post on this forum and I wanted to thank oceanbob for inviting me to this forum. From what I have read, the members seem to be very knowledgeable. I was interested in this thread because I also just obtained a Glock 20 recently. The ammo that I plan on shooting, after a lot of research, is Buffalo Bore 10mm 180 gr. JHP. for home protection, and Double Tap 10mm 200gr WFNGC Hardcast for use as my hunting sidearm. I was on the fence about a barrel since I wasn't planning on reloading at this time. I ultimately chose the Lone Wolf Tactical 5.15 in. barrel to get above the 5 inch mark. I also added a 22 lb. guiderod spring due to the fact that I wanted to stay above 700lbs. of energy without ejecting my rounds 30 feet and the slide slamming the back of the gun. These are the upgrades that I made based on my personal preferences as to what the gun needs to do for me. As you can see from the differing opinions on here, a Glock can be easily personalized for what you want to use it for. All will agree that is a good thing. The first question should be to yourself, asking exactly "what do you plan on using your Glock for"? Once you answer that question, the others come easy.