Hi there! I recently acquired a Glock 19 that I love. Unfortunately however, there isn't ANY 9mm ammo about. So, I am considering trading it it for another model. I thinking I need something that... -Has a wide variety of caliber conversions. 9mm, 10mm, 357sig and etc. This way, I always have something to feed my Glock with! -Size versatility. Can I use extended mags and a longer barrel to achieve the same performance of a full size in a compact? Carry a compact 9mm/40s&w everyday, or add a longer barrel with extended mags for 10mm to carry out in the wilderness maybe? -Same slide? Same frame? I am looking to do some customizing to the gun. Primary reason I don't just buy multiple models for my needs. I understand I may be asking a lot and that I know very little about the Glock models, but any help I can get would be greatly appreciated. Thanks in advance!