Yeah, I know they are both Mack Brothers cans. I’ve not heard or noticed it on other manufacturer cans, just the Mack Brothers. We have a couple of people around here with Mack Brothers cans (the PRS170 MKII I think), I hear it on those too but not the others from other manufacturers.

Hard to say. In part because they’re both Mack Brothers cans, but I know what you mean 😜

A ping like a bell ringing sound is much more common among titanium silencers (vs steel, Inconel, etc) but there are other variables that may cause a ‘twang’ sound, like a certain muzzle device or mount in combination with the silencer. It could even be a specific suppressor design and weight resonating with the firearm somehow and causing the handguard or some other part of the gun itself to ring. It could be something this particular suppressor does reliably, but it could also only happen with this particular ammo or this particular firearm. My guess is that the Zenith *is* more likely to ping a little vs the PRS-170, which had a deeper, more solid tone on the subsonic ammo. Can’t say I could tell a difference at all on the supersonic stuff, but it’s possible that on a different setup (let’s say a 20-inch 6.5 PRC or something) a difference between the two suppressors may show up again.

It’s basically the gunshot causing the metal to ring. Pronged flash hiders are notorious for doing that. A lot of titanium silencers will but, again, it can be very dependent on the specific gun + ammo setup.