THose 3m's are primer guns only,we use them @ work,and thats all they're good for. To the painter,not to sound like a jerk,but spend the $$$$ and get yourself good guns if you want to charge for your work. Sata's are all I use,3000 1.3 rp sealer gun(my old clear gun),3000 hvlp 1.4 base gun,and 4000 BRP 1.3 clear gun,they aren't cheap,but they make a good painter an even better painter IMO. You will struggle with cheap guns,and that includes devillbiss,they are middle of the road @ best. Lastly,one gun will not do it all well,you need dedicated guns to get good results.
Demo'd the new Iwata supernovas when they first came out....slowest gun I've ever laid hands on,and no way in hell would they even come close to how a sata lays down. You want the best,sata is the only gun out there,end of story.
sounds to me that maybe your gun had plugged air passages maybe your air pressure was to high and having problems with your gun and stopping in the middle of your paint job threw you for a loop. mettalics are hard. hope you have good luck with the finish line gun. i use only satas. there are a lot of reasons to get tiger stripies. best of luck on your next try.