CZ 457 Clunky Bolt

[sasquatch98226]

So I have a CZ457 in an MPA chassis. It seems like the bolt is just "clunky". I thought it may be a wear in issue, so I have continued to oil and work the bolt, hoping it would get better. It has not. When compared to my daughters 455 (which is butter smooth), this one seems lift the bolt fine, pull back about an inch, and then it feels like it hits a bump or edge where it then needs to be overcome, and then it travels the rest of the way. When pushing it forward same thing about halfway it hits the bump, and then you push through to close the bolt. Does it have something to do with what appears to be a 2-part bolt mechanism, as opposed to the single piece of the 455? Any ideas? Thanks.

 

[littlepod]

Take it out of the chassis, and see if it still behaves that way.

Sometimes torquing down too much or action screw length has caused problems.

 

[Boatninja]

Run your finger across the Serial number on bottom of bolt. Remove it and careful to not damage any other area, run a fine tooth file over it a couple of times to knock the high spots off. No need to file it off just a couple of swipes will do it. There are a few other threads about it here somewhere.

 

[Grey Kiwi]

Mine had a wee tight spot at the last 1/2 of the the bolt throw (when closing bolt).
Then the penny dropped...it only did it with a certain single shot adaptor.
A quick look showed a chunk of plastic sitting up in the magazine groove that the under bolt guide runs in.
Quick file job solved my problem.
Does yours feel 'clunky' with/without the mag in?

 

[JohnTheFisherman]

So I have a CZ457 in an MPA chassis. It seems like the bolt is just "clunky". I thought it may be a wear in issue, so I have continued to oil and work the bolt, hoping it would get better. It has not. When compared to my daughters 455 (which is butter smooth), this one seems lift the bolt fine, pull back about an inch, and then it feels like it hits a bump or edge where it then needs to be overcome, and then it travels the rest of the way. When pushing it forward same thing about halfway it hits the bump, and then you push through to close the bolt. Does it have something to do with what appears to be a 2-part bolt mechanism, as opposed to the single piece of the 455? Any ideas? Thanks.

How tight are your action screws?

 

[Grey Kiwi]

Just a thought...but is the wee 'recoil' lug in properly? Sitting nicely in it's slot?
Are you now tightening down the action onto a cocked (out of line) lug?
As @littlepod said...take the action out of the chassis first and have a wee look.

 

[sasquatch98226]

Thanks guys, I pulled the action out, and inspected everything, and the put it back in torqued to specs and it seems to be good now!!!! Not sure what it was, but maybe I torqued too tight on the first install? Works great now!!!

 

[WeeHooker]

The bolt on my AT-One is a little clunky as compared to my other 457's. It hits a resistance spot just before the bolt face contacts the round in the mag. Not real bad, but it's there. I've done some bolt swapping and trouble shooting and have determined that it's got something to do with the bolt release ( in the left of the receiver) dragging on the bolt with extra pressure when it is cycled. (If I hold in the latch, It runs smoother. ) I haven't looked into the cure yet but will likely call CZ.

 

[JohnTheFisherman]

Thanks guys, I pulled the action out, and inspected everything, and the put it back in torqued to specs and it seems to be good now!!!! Not sure what it was, but maybe I torqued too tight on the first install? Works great now!!!

Make sure you torque it cz’s specs, not MPA’s.

 

[sasquatch98226]

Make sure you torque it cz’s specs, not MPA’s.

I think you hit the nail on the head right there!!!!

 

[JFricke]

The bolt on my AT-One is a little clunky as compared to my other 457's. It hits a resistance spot just before the bolt face contacts the round in the mag. Not real bad, but it's there. I've done some bolt swapping and trouble shooting and have determined that it's got something to do with the bolt release ( in the left of the receiver) dragging on the bolt with extra pressure when it is cycled. (If I hold in the latch, It runs smoother. ) I haven't looked into the cure yet but will likely call CZ.

Bringing this back from the dead, I’ve got one that seems to have a much stronger bolt stop spring than the other one which causes the bolt to be rather stiff. Thinking about clipping a coil or putting in a less powerful spring. What was your solution?

 

[sasquatch98226]

I over-torqued the action to the chassis. Once I re-torqued to the proper specs the issue went away.

 

[16VGTIDave]

Bringing this back from the dead, I’ve got one that seems to have a much stronger bolt stop spring than the other one which causes the bolt to be rather stiff. Thinking about clipping a coil or putting in a less powerful spring. What was your solution?

Clipping coils off a spring will make it stiffer (fewer coils to flex), though it will also reduce the pre-load when installed. A less powerful spring would be the better choice.

 

[Chubbyduck]

I ran 200 rounds threw my new MTR bolt still had drag so I stoned the numbers on the bolt then polished ,big difference super smooth now the bolt just glides now.I also tried every combination of action screw torque combinations really likes 25in/lb with SK match

 

[EagleEyeShooting]

Their is a known issue that rarely occurs in the CZ457 with the red cocking indicator snagging during bolt lift/recocking.

Disassemble your bolt and remove the Red Plastic indicator and spring to test if this piece is the culprit. If it is, their are aftermarket solid metal indicators you can purchase.