My experience with cans has been limited to the few .22 suppressors and hosts that I own. Seems like you've done what makes sense by changing springs.... However, Silencer Talk has a wealth of info that might help determine w*f is going on with your VTAC/Tundra. I'd be curious as to what you...
Apparently there's a twisting motion involved in the draw, so it isn't strictly passive retention.... I've got one on the way, so I'll let you know how well it actually secures the pistol. It's not an expensive holster & I'm hoping this isn't a case of you get what you pay for!
I picked up a 43C a couple weeks ago but it hasn't seen any range time yet. I'm curious if mine will do the same thing. I'll cast a vote for the leading theory at this point in time and will post pics of mine after 100 rnds or so.. let us know if yours cleans up good.