CZ 457 BOLT SHIMS

[Grimmy]

I have a CZ 457 MTR and was thinking about adding bolt shims, hoping to tighten up my group size.
I would greatly appreciate any and all comments Pro or Con.
Thank you.
All reactions:
22

 

[Mick Boon]

What's the matter with the group size now ?

 

[Grimmy]

Always room for improvement.

 

[I6turbo]

Have you identified a problem of too much headspace in that particular 457?

I've seen posts from owners who claimed that the shimming did not change their group sizes that they could detect, and some from owners who said it resulted in a noticeable improvement.

 

[Lefty38-55]

Before you spend the $$$, 'tis best to measure the headspace that you have now. Info on how to do it, as attached.

 

[Grimmy]

What's the matter with the group size now ?

Always room for improvement

 

[Walkalong]

There's no way to answer your question without more information. Without sufficient information, no, it's doubtful.

 

[Mick Boon]

Always room for improvement

If it works there is no need fix it.

 

[Grimmy]

Before you spend the $$$, 'tis best to measure the headspace that you have now. Info on how to do it, as attached.

I like this idea! Gonna have to try it. Thanks.

 

[Mick Boon]

I've never shot a 22 CZ that was not a tack driver with good ammo. Experiment with the ammo before messing with the rifle.

 

[PzGren]

The bolt shims are relatively inexpensive and come in a set of four or five different thicknesses. They can be used to check headspace and to adjust it, even to adjust it to different rim thicknesses. They are very easy to install and remove.

 

[Walkalong]

Experiment with the ammo before messing with the rifle.

I would agree.

The bolt shims are relatively inexpensive and come in a set of four or five different thicknesses. They can be used to check headspace and to adjust it, even to adjust it to different rim thicknesses. They are very easy to install and remove.

A very good point.

 

[bassjam]

I just happened to measure the headspace on my 457 a couple weeks ago. I'm not happy with the accuracy, with target ammo (severaly types of Eley & SK, even a box of CenterX) I struggly to get 1/2" groups at 50 yards, 3/4" to 1" is the norm. I don't think it's me because I have an old Savage MarkII that shoots sub MOA with Mini Mags with a much worse trigger. I've messed with the action screw torque, played around with barrel cleaning frequency, nothing has changed much. And I measured the headspace at 0.055".

So I odered the shims listed above, put together 0.009" worth of shims, remeasured headspace at 0.046" and headed to the range. My first group was better than I've ever had at 0.228"!!! But it appeared to be a fluke as you can see below.

And I started with a clean barrel and bolt face, but by the time I got to the last 5 round group I could barely close the bolt and really struggled to open it. I've since changed out shims to a 0.050" headspace but have yet to get to the range. I'm starting to wonder if the relief cut in my bolt face is incorrect though, need to measure that because I shouldn't have had function issues with 0.046" headspace.

 

[Lefty38-55]

Confused ... wouldn't you have had to have already measured the depth of your bolt face to determine your overall headspace of 0.055"?

 

[bassjam]

Confused ... wouldn't you have had to have already measured the depth of your bolt face to determine your overall headspace of 0.055"?

Are you asking me? Not necessarily. Headspace is measured from the barrel face to the depth of the white line below.

My question is if the depth between the face of the red line and face of the white line was over 0.045" and contributing to the "hard to close/open" with the bolt shims installed.

But it is not, I just measured that depth to 0.0375".

 

[Lefty38-55]

My question was simply about HOW you may have measured the overall headspace of 0.055", if you hadn't already determined both the depth of your bolt face and the clearance (shim check) between the bolt face and the barrel stub?

Just a question sir ... not a challenge ...

 

[thump_rrr]

Are you asking me? Not necessarily. Headspace is measured from the barrel face to the depth of the white line below.

My question is if the depth between the face of the red line and face of the white line was over 0.045" and contributing to the "hard to close/open" with the bolt shims installed.

But it is not, I just measured that depth to 0.0375".

View attachment 1173390

Did you measure it as per the instructions in the PDF in post #5?

 

[d2wing]

I am curious about the results. I recently sighted in a 457 Lux, my 452 handily outshot it with a variety of very good ammo
I intend to check the bedding etc.

 

[bassjam]

Did you measure it as per the instructions in the PDF in post #5?

I didn't use feeler gauges, I used this method:

CZ-457 Accuracy: The Most Affordable Way to Accurize Your CZ - Gunsmithing Journal

Bolt shims are the most affordable way to improve the accuracy of your CZ-457 rifle. They will tighten your groups and make your rifle more consistent.

kurtthegunsmith.com

 

[TonyAngel]

If your bolt feels right when you cycle the rifle and you have no extraction or ejection issues, it's likely that messing with the headspace will get you nothing and you always run the risk of something stupid happening, like losing a small part that there is a year long back log for.