tidalbass - The 24" factory bbl that came on my CZ457 VPT had some issues new out of the box. I was trying to get it clean before ever shooting it, and just kept getting black patches out of it. Finally got my Hawkeye borescope out and found an area of the bore about 1.5" ahead of the chamber that was covered with what looked like spatters of leading. Unless that was a loose spot in the bore that was allowing gas to leak by the bullet base and melt the skirt, I couldn't understand how that much leading had accumulated if the factory only shot a 5-shot group before shipping the completed rifle. I went in with a bronze bore brush & Shooters Choice, and after 10 back & forth passes, the leading was nearly gone, so I went back in with the brush for another couple of passes, which got rid of all of it. Odd thing was, after putting 50rds of SK Std+ through the bbl, the leading never reappeared, so my theory about a loose spot in the bore kind of went out the window. I kept shooting it with really good lots of SK Std+ and Rifle Match, and after about 500rds, I felt the 50yd accuracy had improved to the point where I was fairly satisfied with it. But when I backed off to 100 & 200yds, accuracy fell apart, to the point where I couldn't keep 10rds on an 8" steel plate at 200. So I sat this bbl aside and replaced it with a glue-in Shilen with EPS chamber, and never looked back.
This was the 3rd 457 I'd bought for my own use, the 1st being an American with a pretty nice stock. But that American didn't shoot worth a hoot out of the box, and never got any better, even after wasting over 1000rds of decent ammo to give it a chance to break-in. This was the 1st rifle I tried the glue-in method on, with a Shilen #5 contour blank that I cut the 1.20" dia shank off of and then turned the tenon on. It wound up weighing about 1/2lb more than the OEM bbl when finished at 23", and shoots as good as I'd hoped for. So in my limited experience with three 457s, the only bbl that shoots good enough to leave alone was the 20.5" Varmint MTR - and while it's pretty decent at 50yds, it's no great shakes at 100 or 200. Makes me wish it was possible to purchase just the 457 actions with the factory trigger, which I'm satisfied with. It's not comparable to the Flavio Fare or Jewell triggers I have on my Vudoo rifles, but it's got to be one of the best factory triggers out there.