Question about pillar bedding

I have a CZ 457 MTR that is pillar bedded. The trigger guard and plate are metal.
When I torque the front action screw, it comes up solid. I can tighten it to change the torque, but it doesn't move hardly at all.
When I tighten the rear screw it seems to tighten ok but when I torque it, it moves half a turn or more going from 20 inch pounds to 30 inch pounds.
The front screw doesn't do that.
It seems like the rear screw should be acting the same as the front. Am I wrong about this?
What kind of issues should I be looking for?

I don't have any experience bedding actions. Any help would be appreciated.

I think I would start by making sure that it's accurate with the torque settings you have, uneven / unequal torque against the bedding blocks can put unequal forces on your action. Using a piece of carbon paper on top of a piece of cardboard under the action before tightening the screws can show where / if there are areas of unequal pressure in the action.


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If there isn't some obvious issue about miss-alinement, crud where the parts come together, or burr on the threads-
it could just be a good snug, sort of interfearance fit where the parts come together.

If that's the case, it could help hold everything together firmly.
I'd look for the obvious things, then shoot it. It might do fine being that way.

Run both screws down to snug before you put the torque wrench on. You'll want to torque the front first. If you're still getting that same reaction, it probably means that your stock is out of true with either the receiver, the bottom metal, or both, and the added pressure on the front is highlighting that with a bit of flex . . .somewhere.

A bit of strategic glass bedding can fix that, but the first question should be, "Is it broke in the first place?", IOW, how does it shoot right now?

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Originally Posted by Bigslug

Run both screws down to snug before you put the torque wrench on. You'll want to torque the front first. If you're still getting that same reaction, it probably means that your stock is out of true with either the receiver, the bottom metal, or both, and the added pressure on the front is highlighting that with a bit of flex . . .somewhere.

A bit of strategic glass bedding can fix that, but the first question should be, "Is it broke in the first place?", IOW, how does it shoot right now?

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It shoots mediocre for the rifle it is supposed to be. It should shoot smaller groups than it does. I have other CZ rimfires that shoot equal to or better than this rifle and they don't have the pillar bedding or the match chamber.
I always tighten the screws as you suggest.
It seems like something is compressing when I tighten the rear screw.
I can't seem to find out what it is or where it is.

You might try putting a thin washer between the tang and the pillar.

I'd suggest torqueing the front screw w/o the torque wrench to a good firm torque. I've always torqued the rear screw to a lesser degree: just enough to assure no slack or movement. I always thought that the front screw was the most important.
Heavy torque on the rear would magnify any small variation in the bedding.

I can't speak specifically to your rifle, but it is general practice when replacing a barreled action into a stock to tighten the front action screw first until it is snug, then to tighten the rear screw. What you feel compressing is probably just the action being pulled down into the stock. Snug also works for the rear screw, but you shouldn't really crank down on it. A pillar bedded stock shouldn't be able to be tightened past a certain point, as the pillar is supposed to be a solid tube and immoveable in the stock, so it shouldn't be able to be compressed. In other words, the pillar should not be loose within the stock and should be the correct length. Perhaps your rear pillar isn't quite long enough. When the front screw is tightened properly and you over-tighten the rear screw you are putting a strain on the receiver which can effect function, pulling it down out of alignment.

DG

Gentlemen, thank you for your suggestions. After reading your posts and thinking a bit, I took the action and trigger guard out of the stock and inspected things. The receiver seemed to be fitting properly so I checked the trigger guard.
This rifle has a two piece trigger guard , so I checked the fit of each piece separately. It turned out the rear piece was rocking slightly in it's cutout.
After inspection, it turned out there were a couple of small lumps of either finish or leftover epoxy from gluing the pillars sticking up right in front of the rear pillar. I removed those down to the bare wood.
Now it fits right and the action torques down correctly on both ends.
I don't think I would have thought of this without your input. Thanks.

And we all want to know if it shoots better.

Chuck40219

on 32 threads per inch 1 turn is .0315 of movement way more than what pillars and bedding should compress. Im suspecting that the back is snug in the bedding and being mechanically pulled in by the screw. 1/2 turn would only be around .015".

How is the rifle shooting?

I will report back on the shooting after my next range trip.

Many rifles benefit from "tuning" via action screw torque. Most have generous holes in their stocks for easy assembly. 22 rimfires may be the worst. About 3 years ago, our rifle range had 3 or 4 Ruger 10-22 owners with accuracy problems. The guy working the check in desk suggested changing the pressure on the action by experimenting with the single screw that held the action. All the shooters found that Ruger's standard torque was too tight, but all had rifles that shot 1/2" or better 50 yard groups at the end of their session.

I got to the range today and gave the rifle a workout. The groups improved, but only a little.
The temperature was rising rapidly this morning causing the impact point to shift during the strings of shots.
It seems the rifle prefers the higher temperatures of 80+ rather than 70s and lower. All the different ammunition shot better the warmer it was.
I had two rifles with me. The CZ 457 Varmint MTR and a CZ 455 varmint Evo.
Here is a pic of the groups.Attachment 286705

The top row is the MTR using Eley Match black box.
The first three on the second row are with Eley Tenex.
I switched to some Aguila Rifle Match($4 per box ammunition) on the last two groups on the second row plus the last three groups on the third row.
The first two groups on the third row were sighters.
The last two rows were with the CZ 455 varmint.

Fixing the bedding made only small difference with the accuracy. I feel this rifle should be shooting better than this.
I can hold well enough with my centerfire rifles to shoot groups under 1 inch at 200 yards. I can hold well enough to keep the crosshairs on the small dot in the center of the circle. The trigger break is coming as a complete surprise. There was no wind to blame anything on today.
I am beginning to get disillusioned with this rifle. Particularly, since a bone stock CZ 452 trainer will out shoot it.

All things considered, that's really pretty good.
Especially for those of us that no longer have what I call 'Those young kid eyes'.

I'd keep doing the last tinkery sort of things. My results have shown a tiny little improvement with those last little things.
Re-polishing a crown, adjusting different seating depths, re-mounting & centering a scope to be sure its adjustments weren't
out to one end or the other, finding a load/bullet a particular rifle just 'likes' more than others, etc.

After the basics, it seems further improvements come slower, and take more work.

Either something is in the way, so your pillar isn't touching your lug, and/or bottom metal; or your front pillar is too short.

Make sure your magazine box is seated correctly.

Oops, I see you have fixed it. Good luck!

Do you have a bore scope to look at muzzle? My brand new Marlin a while back was pushed out the door with a smashed in front bore, every land had a T at the end. I went after it with an 11 degree cutter and shrunk groups dramatically down to I am happy now, the Eley HP subs makes holes to put my pinky in!

I guess I am not surprised. Many mfgs do not change their barrel mfg procedures/quality within a product line and sometimes even across product lines. IMHO, it is why a mfg like Savage produces very accurate budget rifles. All the barrels are made the same, from the budget guns to the competition guns (except for a couple of models).

I looked at the CZ website and it makes no mention of your model having a barrel any more accurate than the lesser priced rifles. What you do get is heavier barrels, better triggers and better stocks. All of which can help the shooter be more accurate. But, a good shooter may be able to shoot the cheapest model almost as accurately as the most expensive model.

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Originally Posted by charlie b

I guess I am not surprised. Many mfgs do not change their barrel mfg procedures/quality within a product line and sometimes even across product lines. IMHO, it is why a mfg like Savage produces very accurate budget rifles. All the barrels are made the same, from the budget guns to the competition guns (except for a couple of models).

I looked at the CZ website and it makes no mention of your model having a barrel any more accurate than the lesser priced rifles. What you do get is heavier barrels, better triggers and better stocks. All of which can help the shooter be more accurate. But, a good shooter may be able to shoot the cheapest model almost as accurately as the most expensive model.

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At the time I purchased mine, they guaranteed that it would shoot MOA. They sent a proof of accuracy target with it in the box.
Now, the website makes no mention of an accuracy guarantee. Maybe there is a reason for that.
I can get many of my groups at MOA or under, but nowhere near all of them.

I would be kinda upset about them 'changing the rules' on you. But, they may have used a special batch of ammo that they cannot get anymore?

Sorry for your issues.