[711b]

Yeah, I used a scope. And then just to be sure I scrubbed the daylights out of it with a brush and several different kinds of oils and solvents. It's also independent of the ammo used. I put all kinds of stuff through it: 711B (which it prefers), other Federal stuff, a few different kinds of Eley, RWS, CCI SV and HV, Aguilla, a bunch of crap Remington, Wolff, and probably others I can't remember now. It has virtually never failed to fire (the only time I can recall is recently when I was trying some Armscorp). Also, I've been all over the bolt at various times. If anything, I clean it too much. And I've stoned off burrs and rounded a smoothed and rounded all the appropriate places.

Looking it over once again after I posted this thread, it struck me that part of the hard bolt is just the bolt itself. At least this is true on cocking. Even with the bolt out of the gun, it's pretty stiff to cock. The culprit there (other than the spring itself) is the "ramp" in the handle that the lug in the rear of the bolt travels up at an angle until it makes it to the top and seats in a shallow detent. That ramp is at a 45 degree angle -- which seems unnecessarily steep to me. I rounded it off at the top some time ago, and that helped a bit in terms of the smoothness, but the rest is just physics concerning that ramp angle (which I suppose I could modify, but I'm not sure I want to). On the other hand, I think the bolt is identical to the one in the 452. So that doesn't seem to account for the difference.

There are some interesting points raised in this thread: 452-455 striker spring. But I haven't done a deep dive into it. However, at some point -- when I can find one -- I may just order and try an original CZ 452 striker spring and see if that's different.

 

[711b]

So my first response to that is "Who WOULDN'T have disassembled the bolt?" 😂 But I guess I never said that explicitly.

Actually, I've disassembled that bolt probably half a dozen times in just the past week. Over the years, I can't tell you how many times I've had it apart either to smooth out some things or to clean it. It's real easy to take apart and put back together. So there isn't any hardened grease or burrs inside it, or any other kind of debris. And all the rough parts and the sharp edges have been smoothed as well. The bolt's perfect. It ain't the bolt -- unless it's just a consequence of the striker spring or the designed bolt mechanism itself. But the bolt is working just as it was designed, and it's cleaned and properly lubed.

One thing I'm NOT getting here in response to my original query is how easy or hard other 455 owners find it to work their bolts. I know that's difficult to describe in writing, but I've seen a number of threads in various forums about stiffness of 455 bolts. That usually comes from new owners and they're told just to work the action until it smooths out, or sometimes they're given hints about what areas to stone or smooth. And then you never hear from them again. One thing I'm looking for isn't general advice on bolt cleaning, but some account of how other 455 owners feel about their bolts and -- if possible -- a comparison to a 452 if they've used one.

 

[711b]

Well, here's another data point ... I've been meaning to check what happens WITHOUT the spring. Seems stupid not to have done this. I think that would indicate if there was something wrong dimensionally with the bold, the bolt handle, the receiver, whatever.

If I assemble and work the bolt without the spring, there is no problem. When closed, it's a tight, but smooth, fit with no play or jiggling. No rubbing or effort on opening or closing. But no sloppiness.

So says that all the "stiffness" is due to the spring. If I lighten the spring, I'll get an easier action. If I don't, I live with what I have. If I lighten the spring, then I MAY face ignition problems. But maybe not since these springs are "one size fits all" where "all" means .22 LR, .22 mag, and .17. So I think some spring experimentation is in order.

This is also consistent with the 452 not having this problem: it wasn't trying to cover three different rimfire cartridges with one bolt spring. Hmmm ....

 

[711b]

Grinding a bit of the spring is my next step too. Hope that helps one of us . . . if not both.

I think I'm going to look in hardware stores and supply houses for possible spring alternatives -- at least ones to experiment on. I'm reluctant to start hacking my only striker spring without some evidence that that would be beneficial. Though I suppose I could invest in one of the aftermarket "extra power" springs (just what I need -- right? 😂) and experiment with that.

 

[711b]

With the first two, the bolt will slide by gravity when I hold the rifle approaching vertical.

Mine definitely does this. In fact, with the very light application of 33MS grease I use, "is propelled by gravity" is probably a better description. The only circumstances in which it hasn't been in this state have been due to poor bedding or torquing of the receiver. I just reworked my bedding (both pillar and epoxy), and it's exceptionally solid and stable now. The 455 action is a pain to bed -- at least in the Boyd stocks as they're produced, but in part just because of the receiver. For the rear section (in front of the back action screw) I added a little block to take up some space and provide a bit more surface for the epoxy.

 

[711b]

1. Flip the spring front to back.
2. is the spring kinked ? Roll it on a flat surface.
3. loosen the grub screws ,loosen the barrel, loosen the magwell screws,
4 . Inspect the bolt guide surface and position.
5. looosn your action screws

Did all that long ago -- except loosening the barrel. It does not appear to be a too tight headspace problem, but I suppose it might be. Assuming barrel torque is okay, fixing that would require either some real gunsmithing or a shim. But then probably the same could be achieved by taking a bit more off the bolt handle where it engages the receiver.

.all my 455 s , like my 452s and 453 s run smooth with only finger tip pressure.

My 455 certainly doesn't. I think I could tune it a bit more with some added attention to the angle of the cocking cam on the bolt and maybe a little more refinement of the camming of the bolt handle with receiver surface when closing, but at this point it's okay for me. It operates smoothly and is no problem in shooting from a bench in timed match stages. Accuracy is superb. So I'm not inclined to pursue it right now. If CZ ever manages to make parts available for the US again, I may tinker with it a bit. I do have a spare bolt handle. But I guess the first thing I'd do is to get a headspace gauge and see what that says.

 

[711b]

Just undo the grub screws and pull barrel, loosen front magwell screw , close bolt, reinsert barrel , tighten gruscrews. Tighten magwell screw .
I dont know why , but this sequence , seems to get everything aligned properly.

Maybe worth a try, but I'm reluctant to mess with it since it's shooting so well -- although it's difficult to see how this would affect that, I suppose

Stop filing your receiver, if you must , file the bolt handle, it can be replaced.

I have NEVER touched the receiver with a file. Only the bolt handle, and that only very carefully with a small diamond file.

 

[711b]

if you have a buddy with a 455 , see if their bolt does the same thing in your gun.

Good idea. As I mentioned, I do have an extra bolt handle (got it thinking I might at some point put a different knob on it, but never got around to that). When I tried it, it was even worse than the original. Worked well just working the action and taking a few shots with it. But I took it to a match and after about 40 shots it got REALLY tight. From this, we learn that dimensions of parts may not be dependable or uniform. It turns out that if you actually MEASURE some of the dimensions on the two bolt handles, there are differences. 🙄 And both are CZ bolt handles, direct from CZ.

We MIGHT also learn that the problem lies in the barrel seating so that when it heats up, and headspace decreases, everything tightens up -- and so the headspace MAY be a bit tight. But that's something of a stretch and involves other assumptions. And I see no other signs of tight headspace -- though that's just looking at and measuring cartridge rims, and without a gauge. Of course, the problem may not really be "headspace", but that the barrel is just set into the receiver a bit too far.

Finally, if I take the spring out, there appears to be no effort in opening or closing the bolt. It's this that inclines me to believe the problem is with the bolt handle as it cams into receiver when closed, or else is with the angle of little camming area on the bolt itself. All of these things interact and the effect is additive, of course. So changing any one of them (or a couple) may have an effect. But it's perfectly shootable now, and wonderfully accurate. So I'm just going to be taking a more leisurely approach to "fixing" it.

 

[711b]

Okay, but if you diagnosis this as a headspacing issue based on this fairly crude test, then exactly how much should you shim it? Just "by feel"? But doesn't that provide the very real possibility of affecting uniformity and accuracy of shots? If you're serious about fixing a headspacing issue, shouldn't you be doing that with go and no-go gauges? Or at least by doing it empirically by significant accuracy testing with different shims?

Currently, I can shoot 10-shot groups at 50 yds with this gun that go into a half inch. I'd hate to lose that just for the sake of a very slightly smoother bolt open/close.