Congrats on the G20 gen4. My first Glock was a G20 gen3 . I came here with the very same question on which drop-in barrel to purchase, or do I even really need one. I read every comment and boy the guys here made my decision on a barrel tough. Lonewolf, Bar-sto, StormLake, KKM Precision and the original factory barrel. The only way for me to make a educated decision was to call all the places listed above except for Glock. Well they all were great people but one just stuck out and appealed to me. KKM Precision 6" drop-in. I called KKM and spoke with Kevin and he took the time to explain their product. I will say KKM talks the talk and walks the walk. I have ran this barrel for a year now and I couldn't be any happier. Just to say I returned to KKM for a G35 drop-in and put it in a new gen4 G35. I hope I have this right but I believe I spoke with Luke. I have ran this barrel for 2 weeks now and I love it. Both barrels have ran Nosler,PowerBond, Hornady xtp, Winchester,Berry's. It doesn't matter what you put in the pipe KKM runs with it. Take your time and do listen to all the good people in here,weight it out and make an informed decision, make some calls to get answers from the people that make the product.
p.s. I will be watching this thread ...cause I've been peeking at the Red Dot sights...I just don't know what to think....