In my experience…
I’d look for whatever nozzle doesn’t wobble on the nozzle tube, has good finishing, cutouts, and is ordinary M4 length (adjustable ignores this). Usually I prefer plastic with no o-ring, and I literally dig around in a box I have from Guges until I find one with a good fit.
For aftermarket I prefer Maxx adjustable, which are wobbly at times but can at least be tuned by length to help with other issues. If you could source a Krytac or VFC stock nozzle I’d call that great. Arcturus stock nozzles are also high on my list. I’ve been through SHS, RA, and some other aluminum double o-ring nozzles… but just not what I like.
Including price in my rating, I’d go with these pairings combined with whatever nozzle fits your cylinder head best:
G&G rotary hop unit w/ an ML hop rubber or maybe a TNT silicone flathop.
Arcturus polymer rotary with a PDI W-hold or a Modify Baton flathop.
That Maxx should fit an ML rubber well, or at worst a G&G Blue/Green.
That Prowin should fit a PDI W-hold, Modify Baton or a TNT T.Hop (TNT needs special thin nub, since it’s a tall contact patch).
Here’s some of my compatibility notes about hop rubbers and hop units, assuming good GB shell alignment in all cases:
Maxx nozzles (particularly the adjustable), will work with these hop units with the right rubber: Prowin, Prowin Clone, Maxx, Krytac, Lancer Tactical (generic red Chinese), Arcturus pending (Need to get out and test).
I dislike Prowin Clones like the Dytac unit since I‘ve found them to cause feeding issues due to how the seat with the upper receiver and the gearbox. Not always, but in some receivers. Mine caused issues in a build using a Cyma platinum receiver and Lonex Diecast box. A regular Prowin worked fine.
There are two kinds of rubbers in my experience: China spec, and Taiwan spec. This is very general, but Taiwan spec are thick around the front, and won’t fit correctly in: Arcturus, TM, Prowin, Prowin Clone, Lancer Tactical, or other generic units.
These rubbers include: Maple Leaf rubbers, TNT silicone flathop, Silverback Silicone rubbers, G&G green and blue are borderline, and will still fit in regular units with maybe mild sanding of the lips.
Maxx, G&G, and other Taiwanese units usually fit these thicker rubbers easily in my experience.
China spec is thinner, both around the front “shoulders” and usually the rubber in general. These include: TM stock (obviously Japanese, I’m being general), Arcturus stock, PDI W-hold, Madbull red shark, Modify Baton flathop rubbers, TNT T.Hop.
Arcturus is actually even skinnier and more restrictive than most, and actually disallows usage of G&G rubbers, TNT rubbers, and others IME.
