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CZ 455 bolt tight on closing

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Yes, another of these threads. :rolleyes: Yes, I have read the others. I guess I'd just like some impressions from others who may have encountered this in order to determine what my realistic expectations should be and whether I should pursue doing something to "improve" things -- either by myself or via CZ.

Background: I had a CZ 452 and loved it. Alas, in a fit of irrationality, I replaced it with a 455. The 455 is, in itself, great. It's superbly accurate. I love shooting it. But it had this "issue" from day 1, I've improved it about as much as I can with simple methods, and it still seems a bit odd to me.

The action is very smooth -- I mean REALLY smooth. No problems there. I've put several thousands of rounds through it. Everything works. When I close it on an empty chamber, there is some resistance, but that's to be expected as the bolt handle cams against the action surface. I can close it with just thumb pressure on the (stock) bolt knob, but not exactly "butter smooth" or totally effortless. Opening the cocked bolt is pretty easily done with just the index finger.

Closing the action on a chambered round isn't really much different. But as the action heats up, there does seem to be an increase in the effort needed to lift the bold handle and cock the bolt, and to close the bolt to chamber the round. But I can't quantify this.

Looking at this, it's hard to see what I'm complaining about. But I remember the 452 action being virtually effortless to work fast with index finger and thumb -- like "Olympic speed". The 455 isn't there.

What I've done:
  1. Checked to be sure eveyrthing seems good with the chamber, the extractors, the bolt itself, etc. No obvious problem.
  2. Very carefully polished various bearing surfaces of the bolt itself and the cocking mechanism.
  3. Carefully filed/stoned the surface on the rear of the receiver notch that the bolt handle cams against to close and seat the cartridge. This has definitely improved things, but not entirely. I actually bought a new "backup" bolt in case I screwed this up. When I switch bolts, I don't see any difference in how the bolt is seating, I see no signs of excessive headspace, but the running the action with the "new" bolt is clearly stiffer than with the old one. I've had the experience with the new bolt that when the gun heated up, the action became almost impossible to work. Although visually identical (except for the hole in the new bolt knob, its matte finish, and an odd deep rectangular "cutout" in the underside of the bolt handle), there do seem to be some minor dimensional differences on the order of fractions of a mm.
I don't believe I've replaced the original striker spring. I have no record or memory of that, and there's no spring in my parts boxes that looks like a striker spring for a CZ 45x.

So at this point I'm pretty sure I haven't screwed up anything (particularly headspace), and have achieved some improvement to where I feel the functioning is "okay" to "good". I'm wondering if I should attempt to go further in terms of filing/stoning the bearing surface of the bolt handle or quit while I'm ahead. I'm wondering if this is just the nature of the beast and the 452 just had a slicker action (possibly because of changes for the 455 made to support multiple calibers). I guess that if I'd never had the 452, this situation with the 455 wouldn't be bothering me at all. :rolleyes:

Comments, suggestions, advice, ridicule ...? At this point I'm just mostly curious and looking for peace of mind. 馃槀
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Hi 711b - When you said you've checked the chamber, did you look with a borescope for carbon obstructions? just a slight chance that's it. My 455 takes a bit of effort compared to my other bolt actions but I attribute that to the snug headspacing. Also, does this occur with several diff brands of ammo? I've found some have 'thinner' rims, thus tighter bolt action. One last thing is the possibility of internal bolt probs, like irregular inner surface rubbing on the firing pin spring or even heavy lube inside? Just some guesses . . .
 

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CZ455
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Discussion Starter · #3 ·
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.
 

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CZ455
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Discussion Starter · #5 ·
So my first response to that is "Who WOULDN'T have disassembled the bolt?" 馃槀 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.
 

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CZ455
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Discussion Starter · #6 ·
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 ....
 

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Sorry to have assumed you might have overlooked that action. I've seen too many on these various forums that just complain and look to spend more money without determining the real problem. Like the $1K 10/22s many are in love with.
Glad that you found the spring is the main culprit, I've wondered about mine as well. I've had my bolt apart prob as many times as you trying to get my safety to run without breaking my thumb in the process. Seems the spring is too strong for that as well since I've polished the safety lever numerous times. Grinding a bit of the spring is my next step too. Hope that helps one of us . . . if not both.
 

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Discussion Starter · #8 ·
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? 馃槀) and experiment with that.
 

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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.
I have three 455's in .22LR:
Varmint (10/2/2012, S/N B116xxx, 3,952 rounds),
Training Rifle (9/5/2014, S/N B601xxx, 2,345 rounds),
UltraLux (5/5/2017, S/N C201xxx, 2,150 rounds).

With the first two, the bolt will slide by gravity when I hold the rifle approaching vertical. My newer UL has not yet achieved that glorious state, but the bolt is a joy to operate.:)
 

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CZ455
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Discussion Starter · #10 ·
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.
 

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Polish the spring and where it lives and/or buy a spare and clip a coil or two. I mess with springs on my rifles all the time. When a spring gets compressed unless it鈥檚 on a guide in an oversized channel it kinks to the side and rubs increasing the friction. Remove as much friction as you can.
 

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I can sympathize with the OP, my Bergara BMR 22LR action was very stiff too. My problem was that this is my first bolt action rifle, so I didn't have anything to compare it to. However, watching YouTube videos made me realize that other Bergara BMR actions are no where near as stiff as mine. I watched in disbelief when a guy grabbed his bolt and cocked it in his bare hands.. Mine is too stiff to do it even when I hold the bolt with a towel. Also, things start to visibly bend when I try to cock the bolt off the receiver by twisting it. Also, he cycled the action and cocked/decocked the action with very little visible effort. My action is definitely too stiff to do that.

I too resorted to polishing the various surfaces of the cocking ramp and detent, and have similarly concluded that the firing pin spring is too stiff.
 

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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

these are guns they make stronger striker springs for, I doubt if yours is too stiff, something is out alignment, or has too much. Torque pressure .all my 455 s , like my 452s and 453 s run smooth with only finger tip pressure.
 

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Discussion Starter · #14 ·
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.

Toomany22s said:
.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.
 

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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.

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

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Discussion Starter · #16 ·
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

Toomany22s said:
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.
 

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Discussion Starter · #18 ·
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. 馃檮 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. :)
 

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One of my 455s has serial number that matches rifle on bolt. The other doesn鈥檛. If one loosens barrel grub screws and and loosens mag screw a bit and then cycles bolt and it gets substantially looser that indicates likely headspacing issue. Get a few shims. 001-.003鈥 and try. Lilja sells them I think that fits your barrel shank.
 

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Discussion Starter · #20 ·
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.
 
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