Eddie,Be careful of unbalancing your pellets with powder coat that is unevenly distributed in their skirts. I notice some variability in your image, cropped below.
PC on pellets can be done with real sprayers... Build a metal plate with a bunch of metal pegs sticking up, then just put the skirt on the pegs and spray like normal powder coat.Alternate would be shake and bake and grasp the pellets at the waist where they don't rub. All my cast ammo has a grease groove, so I try to grab them there.The Eastwood Hotcoat mirror colors seem to work really well, but I have some of the "regular" Hotcoat colors that I just bought to try. The mirror one that I have flows out like glass and normally covers up bare spots.
Unless a barrel is exceptionally accurate, I fire lap all of my slug barrels. it has never failed me and the results are fantastic. However, you must not over do it. For actual pellet type barrels (which are softer steel) that I shoot slugs in, it requires less fire lapping than a fire arm barrel.I finish with my own blend of Ultra Fine Abrasive in the form of Diamtomaceous Earth (SP?) mixed with FP-10 lube, and final with a patch coated with Flitz Metal Polish. I have had barrels that would lead up in 25-35 shots go to 200-300+ slugs before needing a simple pull thru. I always finish the process with a light re-crown. In nearly all cases, the barrels so treated give better accuracy both in initial accuracy and the lack of accuracy loss due to leading for a much longer period of shooting. Some have found waxing after the polish adds even more resistance to the leading giving enhanced performance for longer (shooting a higher number of shots) sessions Before a patch or pull thur is required to bring accuracy back to its top performance. an added bonus is the lack of the need to re-lead the barrel before accuracy returns after cleaning. A simple pull thru with a dry patch is all that is required, with accuracy usually returning instantly, or with very few shots required for it to return to its top level ion a given barre.It must be pointed out that slug barrels see higher friction than what we see in pellets, and although good pellet barrel may not see accuracy degrade for many thousands of shots, slugs change this sou to their much larger contact foot print on the lands and grooves. Proper sizing of the slugs and polishing of the bore can give greatly enhanced of performance. A higher degree of accuracy, higher fps/fpe, and maintain this level for a much greater and more predictable period of time or shot cycles. Yes, it is tedious and time consuming, but I find the process well worth the effort. Knife