torque specs for cz455 action?

[turret]

i removed the action on my cz455 today to install the dip aluminum magwell and extended mag release. when i put it all back together i torqued the action screws to 53 inch lbs according to the owners manual. then i couldn't get the bolt to cycle.

i realized that the rear action screw was coming up too far and essentially locking the bolt in place. i then removed both and started out light. finding out how far i could torque it while still having the screw stay flush or slightly below the receiver. i couldn't even get to 15 inch pounds.

what gives?

will a dip bottom metal fix this?

what do you guys torque your cz455 actions to after working on them?

thanks

 

[sphillips]

Re: torque specs for cz455 action?

I don't have a 455 , mine is the 452 Varmint i had to play around with mine to find what it liked . 25 On rear and 20 on the front . My 16 '' American likes 25 on both front and rear action screws. Never had a problem with the action screws locking up the bolt .

 

[1shot2kill]

Re: torque specs for cz455 action?

30/30

 

[justin amateur]

Re: torque specs for cz455 action?

Install pillars to correct the action screw length problem.

When I split the plastic mag housing on my 455 I contacted CZ-USA.
Talked with one of the gunsmiths who told me that the mag well screws
were meant to be torqued to 10 inch/lbs, but that a torque wrench was rarely used
when installing the plastic mag housing. Screws were tightened until
the housing contacted the receiver, then tightened 1/8 turn more.
If the plastic tabs on the housing were distorting, then the screws were too tight.
Torque specs for the barrel screws are supposed to be 5 NM (44 inch lbs)
and the action/stock screws are 6 NM (53 inch lbs) for dry threads.
But since most of us lubricate our receivers, torque should be less.
Recommendation is to use about 70% of dry torque specs.
That means no more than 31 inch lbs on the barrel screws
and no more than 37 inch lbs on the stock/action screws.
Over torquing the barrel screws has been reported to distort the firing chamber.
Compressing it from round to elliptical in shape. Not good.

 

[turret]

Re: torque specs for cz455 action?

i didn't even touch the barrel screws (luckily it seems) as i had no reason to.

however, i'm worried that my stock is fubar now since i can't even torque the action screws to 15 lbs without the rear screw protruding too far and pinching the bolt. they are barely finger tight.

i tried calling cz today, but they are closed 'til monday.

 

[TOP PREDATOR]

Re: torque specs for cz455 action?

perhaps adding a flat washer to the bottom will shim it enough that you can get your torque and not have a little clearance problem with the bolt. the pillars should work too, even some metal spacers found at home depot trimmed to length.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jaia</div><div class="ubbcode-body">
Over torquing the barrel screws has been reported to distort the firing chamber.
Compressing it from round to elliptical in shape. Not good.</div></div>

^^^that's a real good piece of info.

 

[turret]

Re: torque specs for cz455 action?

forgive my ignorance, but is there a tutorial on installing pillars? i don't know the first thing about bedding.

 

[justin amateur]

Re: torque specs for cz455 action?

turret, I'm not a gunsmith and not very knowledgeable when it comes to firearms. Even so, I managed to install a set of pillars in my 455. I used Hillman silicon bronze bearings to create the pillars, and 5 minute epoxy to bed them in the stock. Tools used were 100 grit sandpaper, drill with countersink bit, file to shorten the sleeve bearings to length. Took one evening to file, sand, and dry fit everything until I was satisfied with the results. Took 10 minutes to do the epoxy work. Not difficult at all.

Relevant post...

http://snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=3291738

 

[turret]

Re: torque specs for cz455 action?

thanks for the link jaia, much appreciated. what did you do to wax the barreled action? so you just add the dots of epoxy, set the action in place and wait for it to set up?

 

[justin amateur]

Re: torque specs for cz455 action?

Definitely wax the action before doing any epoxy work.
4 coats to ensure release after epoxy cures.
I had some mold release wax, but neutral shoe wax works too.

Place the dots where they'll do the most good,
then when the epoxy just starts to set,
seat the action in place and thread the stock screws
in place to prevent movement while the epoxy cures.
You could even add washers under the action, front/rear
to lift it back to where the screws no longer
interfere with the bolt. Gotta love epoxy,
stuff is like liquid duct tape, use it everywhere.

What's great about the dot shims is that they are easily removed,
using a razor edged wood chisel. They peel off looking like fake fingernails.
Also more can be added at any time you feel the need.
We're not talking centerfire recoil loads that need a full bedding.
I've redone mine twice to create greater support at the rear
of the action. Filled the gap between the flat and the underside.
The epoxy ledge and the spacer at the rear of the inletting
took the last of the play out of the stock/receiver fit.
Made a visible difference in my 5 shot groups.

 

[isaaccarlson]

Re: torque specs for cz455 action?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turret</div><div class="ubbcode-body">forgive my ignorance, but is there a tutorial on installing pillars? i don't know the first thing about bedding. </div></div>

I torque to 30 in lbs with pillars.
I have a video on youtube showing how I do it.
http://youtu.be/b0PyUoOp_g4 http://youtu.be/b0PyUoOp_g4