I used to run a YHM Phantom on my Century G3 and it worked great, looked good, and allowed me to mount the G3 bayonet.
Long story - The Century came neutered, so I threaded it. Unfortunately, there wasn't enough material (or even a shoulder) to go with the 15x1 original thread size, so I cut the end at 1/2x28 and opened up the YHM for a .30 bullet. It was like that for years before I went with an HKParts.net HK flash hider in 1/2x28, but I found the bayonet would hang off the end of the barrel. It looked great, but the fact the bayonet couldn't attach kept bugging me, so the YHM went back on. Keep in mind the HK and Phantom are roughly the same size, but the problem is the HK threads are recessed about 1/2", where as the Phantom (and most AR-type FHs) are threaded from the very end. You can actually see how much further back the HK sits in the pics below. Recently, I found a 1/2x28 to 15x1 adapter so I put that on and bought an original 15x1 HK flash hider. The extra half inch for the adapter is long enough to hold the bayonet back on. So, typical of my luck, I now have a YHM Phantom in 1/2x28 for .30 and an HK flash hider in 1/2x28 sitting in my extra parts bin.
G3 with YHM
G3 with HK FH in 1/2x28
I don't have a picture of the latest setup with the adapter. Soon though, soon.