I posted somewhere else my experience with the KKM 10mm barrel.  I got the 5 inch threaded for Lone Wolf Suppressor.  It is great and after 3 years I have no complaints at all.  ONE THING; however, make sure you tell KKM that you intend on using the HEAVY ammo (from UNDERWOOD - there the best IMHO, Buffalo Bore or Double Tap),  I had to send mine back as it gave me several FTF (failure to Feed), called them up,and they said " we have to re-size-modify the bullet chamber for people that use the heavy loads".  You figure that anyone that would by a $300.00 barrel would be using the GOOD AMMO, whatever!!!  Once I got the barrel back, it NEVER "FTF" again, EVER.  I loved it, (LOVE IT) especially when I use the Lone Wolf Muzzel Brake; when combined with the DPM Recoil Reduction System (Triple Spring system), the recoil is just about the same as a +P+ 9mm round.  The DPM really made a difference.  Here is DPM's Link:
https://dpmsystems.com/en/

I have had a KKM 5 inch barrel for my Gen 4 G20 for over 3 years now (2013), and at first it would FTF (Fail to Feed) every ONCE in a while; however, I contacted them and they had me send it back for Mods.  Apparently you have to INFORM them that you intend on using the HEAVY ammo (Underwood, Buffalo Bore, Double Tap) and they modify the bullets Chamber (I don't know what you call the area that houses the round).  Once I got it back, it NEVER done it again.  I can attest a decent difference with my shooting skills once I got the KKM barrel.
    I had them make me the threaded version (5 inch) for the Muzzle Brake (Suppressor) and it just overhangs just a little.  GREAT BARREL, GREAT IMPROVEMENT!!!  I recommend them; however, make sure you them that you intend on using the HEAVY AMMO from the big three (Underwood is BEST, Buffalo Bore is second, and Double Tap is THIRD), so they can mod the round (bullet) housing for the heavy loads.  The clearance is MUCH tighter than the stock Glock barrel by far.