Alright, this is going to be a bit long, but could be useful down the road.
I brought my CZ 455 to a shoot, as there was the opportunity to shoot a qual. This is a pretty modified rifle, Boyds stock, scope rail, optic, and an aftermarket trigger.
I had a gunsmith friend of mine install a Yo-Dave trigger kit as he happened to have one sitting around, this modification has proved reliable for several bricks of ammo, to include one Appleseed where I shot as a student. Sometime from then, to this last weekend the sleeve on the pin that alters the sear engagement wore enough to cause issues. Namely that the bolt was no longer being retained by the sear but also trigger weight dropped to a point were the rifle was not drop safe. Basically the rifle was no longer usable for Appleseed shooting.
The Fix,
Very simple, remove the bushing on the sear pin that alters the sear engagement. Took about 5 minutes with a punch, a small hammer and a pair of pliers.
So if, in your journey on the trail, a shooter with a CZ starts to have his bolt pop out during rapid fire... here is your fix.
I found the trigger on my 455 American to be quite nice compared with many other rifles. I have no plans for a trigger mod; however; I appreciate you posting your solution. Readers might like this sticky thread from the RimfireCentral CZ/Bruno page on the trigger with photos, https://www.rimfirecentral.com/forums/showthread.php?t=330293