To truly realize the potential of hot 10mm rounds you really need a barrel 5.5'' or longer in my opinion. With that in mind, I picked up the LWD 6.6'' 10mm threaded barrel for my Gen4 G20.
When the barrel first arrived I threw it in the gun and noticed a problem; it was way too tight round the lugs and hood. The gun wouldn't cycle properly due to the amount of friction from the tight lockup. I called LWD and they told me to send it in with my slide, which I did. Fast forward two weeks and I had it back in my hands and was running rounds through it.
-100% reliable with all ammo tried thus far
-Standard 9/16x24 threading allowing for use with most popular suppressors
-Heat treated 416 stainless steel
-Theoretically a drop in part (I have several other LWD barrels, they worked out of the box)
-Standard rifling allows the worry free use of lead reloads (more on this in the video)
-Extra velocity compared to the stock barrel
-Fully supported chamber (no evidence to any type of deformation/damage to the fired cases)
-Polished feed ramp
-Mine didn't fit properly out of the box
-I'm not a fan of the logo; I'd much prefer something less obvious like KKM and Stormlake do
Here's a video of some shooting, a demonstration of the chamber support vis-à-vis the Gen4 factory barrel, and a chronograph test using Underwood 165gr Gold Dot rounds:
BARREL HD VIDEO REVIEW LINK
Underwood 165gr Gold Dots: 1418fps, 736 ft/lbs energy
Underwood 165gr Gold Dots: 1559fps, 889 ft/lbs energy