New CZ 457 bolt super tight when closing

DD AT4 said:
Thanks again for everyone's thoughts and ideas, this is such an amazing community!

I'm going to try some different brand ammo as everyone has suggested, and work my way through there. Even though I thought I scoured all the message boards, I'm finding more and more and more posts about the same thing now all of a sudden, grauhanen, thanks for the links!

When cycling the bolt without ammo it feels easy, but with ammo is when it's hard to close it. One thing I did notice was with the CCI SV, some felt easier to close than others, so it seems to line up with ammo consistency being the culprit.

Just wanted to make sure I wasn't causing damage, but if tight ammo is the case, should I stop using this ammo altogether?
Click to expand...
Try and get some SK, Lapua or Eley ammo and give these a try. Maybe you already have a 'match' setup and can live happily ever after shooting quality match ammo. A few rds is all you need to figure out what is what

US branded stuff can have some heavy rims or wondering QC so I wouldn't suggest there is anything wrong with the rifle yet.

If it functions well on match stuff, then you have got a great set up and saved some hassle and addn costs trying to shrink headspace later

Enjoy

Jerry
 
grauhanen said:
Unless headspace is incorrect from the factory, the problem remains as described earlier.

Before looking at shims, check the headspace to confirm that it's good. Use a headspace gauge such as a Go gauge.

View attachment 1033437
Click to expand...
In my case, it was rim pinch that was the issue. Likely stack up of bolt forward at minimal tolerance, barrel tenon at max tolerance. That's my story and I am sticking too it. Root cause analysis was correct because the countermeasure worked.
 
Meroh as you mentioned, barrel shims were what I needed!

I also ended up taking headspace measurements the best I could with a caliper and then added a .002 shim barrel shim. It made a huge difference. The bolt now closes so much easier but still a little snug, as expected. Compared to how it was, I'm assuming the tolerance was way too tight coming out of the factory, maybe for my specific rifle.

Took it the range and tried different ammo as suggested. The bolt closes on SK and Eley so much easier than before and still shoots them extremely accurately. It even works well on CCI SV which was the hardest to close on.

Appreciate everyone's help and advice here!
 
DD AT4 said:
Meroh as you mentioned, barrel shims were what I needed!

I also ended up taking headspace measurements the best I could with a caliper and then added a .002 shim barrel shim. It made a huge difference. The bolt now closes so much easier but still a little snug, as expected. Compared to how it was, I'm assuming the tolerance was way too tight coming out of the factory, maybe for my specific rifle.

Took it the range and tried different ammo as suggested. The bolt closes on SK and Eley so much easier than before and still shoots them extremely accurately. It even works well on CCI SV which was the hardest to close on.

Appreciate everyone's help and advice here!
Click to expand...
You are very welcome, I am very happy everything worked out.

A little snug is good; I would go a step further: Since you have already added .002, maybe try adding another .001 (your kit may have a .003 shim in it). Do another accuracy check, and see if the bolt is a little easier and smoother to operate.

I always stress to the younger engineers in my department to always look for the easy answer first. :)
 
Bubba Yugga said:
How'd you manage the I.D. and O.D. cuts (and concentricity) to fab the shim? What brand? Would Czeske piwo do?
Click to expand...
Tyskie So, I drew it with a dividers, scoring the Aluminum, ID and OD, then using a good quality manicure scissors, cut it out, drilling a hole in the middle to get a start with the scissors I made 4 thinking I would screw up a couple. Only screwed up one. LOL
1763056454684.png
 
I found CCI SV tight in my MTR as well. Not terrible, but tighter than I liked. I switched to S&B Canadian Match for my practice ammo and it allowed the bolt to close much easier. Tenda has it by the case for a very good price if you're in the market.
 
markt said:
I found CCI SV tight in my MTR as well. Not terrible, but tighter than I liked. I switched to S&B Canadian Match for my practice ammo and it allowed the bolt to close much easier. Tenda has it by the case for a very good price if you're in the market.
Click to expand...
How does it shoot, and at what range are you shooting it?
 
In my MTR, SBCM shoots as well, if not slightly better, than CCI SV up to 100yds. I've not tried further distances yet. However, some have found that Norma Tac-22 works better in their MTRs for practice ammo. Best thing is to get a box or two of each and do your own testing before committing to a full case.
 
markt said:
In my MTR, SBCM shoots as well, if not slightly better, than CCI SV up to 100yds. I've not tried further distances yet. However, some have found that Norma Tac-22 works better in their MTRs for practice ammo. Best thing is to get a box or two of each and do your own testing before committing to a full case.
Click to expand...
I will try some when it warms up.
 
You must log in or register to reply here.
Back
Top Bottom