I am buying a Gen 2 Glock 19 with two full cap mags. One of the mags will not hold the slide back, and will need a new mag spring and follower at least. Plan on refirbshing both mags anyway. IMSI springs are my preference for mag and recoil springs. I also need, since I have no idea how well this gun has been taken care of, (Looks pretty good with no failures other than the slide lock back. in the 100 rounds I shot though it) so I am planning on at least replacing the critical parts. I have worked ( read tinkered) on Glocks before but am by no means an expert. THIS WILL BE A DAILY CARRY GUN NO TRICKED OUT ACCESSORIES here, just what works and works every time. My question is that I don't know what are considered "critical" parts. I am thinking about the following: (If there is anything else please let me know) 1. Mag rebuild as stated above. Has a plus 2 floor plate on one that will be replaced with stock floorplate. 2. striker spring, stock weight (ISMI) 3. Recoil spring, ISMI stock weight, for carry. 3. One or two additional recoil springs to play with. I do not know what weights may help with perceived recoil or muzzle flip. Some suggestions here would be helpful. 4. Stainless-steel vs. tungsten guide rod, non captured, as to facilitate spring changes. (Any known problems with these?) 5. If I recall correctly, there is a spring on the slide stopped that is prone to failure. What is the proper name for this part so that I may order one to have as a reserve. 6. Extended magazine release the semi oval type, one preferably that does not require frame modification for installation. I know that glockmeister, top Glock, and lone wolf all carry omething similar to this. It appears that lone wolf requires cutting the frame to use one of these. It also appears that the ones from top Glock and Glock Meister do not. Is this correct? 7. Meprolight, Trijicon, vs XS, some other brand of fixed sight. BTW I do not have a site pusher. This gun has stock sights currently. 8. In the trigger group, I am planning on staying with a five pound trigger. Is there any advantage of changing trigger springs or bars in order to get a smoother, more crisp, trigger with less overtravel without sacrificing reliability? As you can see, most of my questions that I need the most help with our deciding on 1. Sights 2. Recoil spring weights 3. Trigger group. Thanks for your help, Trying to place an order this afternoon. Would prefer to get everything from one store.