Home Forums Hunting & Shooting Rimfires Torque tests

I recently got a LH CZ 457 American and since they make a LH Varmint model got one of those, too. I installed a lighter trigger spring in each one and when putting them back in the stock I used the CZ manual's torque spec for the action screws of 3.5 Nm which translates to 31 inch/lbs.

Love the CZ rifles but their action screws are a bit soft and even with a good Torx bit they can get buggered up some. So I was looking at the DIP website for CZ 457 replacement action screws and saw they recommended starting at 20 inch/lbs and increasing in 2 pound increments until you find the sweet spot. First trials with the new American had shown it to be kind of finicky so I figured what the heck and gave it a try on both rifles.

20 inch/lbs seemed kind of light, it felt barely past snug and even if they're only .22's I had visions of vibration from firing gradually loosening those screws so I started at 24 inch/lbs and went up in 3 pound increments - 24, 27 and 30.

I'm here to tell you, they're onto something. Shown here are the trials this morning. I used Norma Tac-22 since most all of my rifles seem to like it, including these two new 457's, and the results should be reliable. Normally you'd tighten the front action screw on a rifle first but since CZ's have the recoil lug at the rear of the action I tightened the rear screw first and then the front. Didn't try it the other way so have no basis to say it's significant but it sounded logical.

Top pic is the American, 24 inch/lbs seems to be what it likes. Second pic is the 457 Varmint and it clearly shows a preference for 27 inch/lbs.


457 American. Even the best group at 24 inch/lbs is kind of strung horizontally but it's definitely superior to the other two settings.




457 Varmint. This one obviously prefers 27 inch/lbs. Since good artists sign their work, I always sign my groups with a signature flyer. At least that's my story...




Being an experimental sort I may try this on some other .22's to see if has any affect there.

Where's mathman at? Do you know how many times you'd have to shoot and re-test to verify the statistical average needed to produce an informed decision? I'll give you an example. Here are 3 different groups. Same torque setting on all 3 groups. In your test, you are using ammo that is not as predictable or precise as the ammo I'm using in this example:

First group:



Second group:


Third group:


On the second group above, the ammo was more consistent and maybe the wind died down a bit. It really proves nothing though, except the rifle seems to like it.

Now, with your ammo (Norma Tac22). I've shot that stuff before and it has acted wonky at times. In my 10-22 it's shot 1/2" 10 shot groups and then the next group will be 1", so it's unpredictable. My Savages absolutely hate the stuff.

Also, like I've said many times before, if your action screw torque has that much of an effect on accuracy/precision, that means you have a mechanical issue with your rifle that needs to be corrected. Hence pillars or proper bedding. The 10-22 that I shot in the above picture, shoots like that right after I pull it out of the stock and tighten the action screw by hand. Absolutely no POI shift either. That is the way a good rifle should perform.

A couple questions:

1. Barrels floated?

2. With a bore sighter installed, does one see any crosshair movement as the action screws are tightened/loosened?

2. With a bore sighter installed, does one see any crosshair movement as the action screws are tightened/loosened?[/quote]


Wouldn't you use a dial indicator for this

I'm an unbedded CZ you definitely see torque values have effects. I shot for the team that CZ, Manners, and Bartlein put together a couple years back. My gun liked a number of values as provided so I had Manners bed it and I torque to 45 in*lbs.

That would work too, but I was able to easily determine that my receiver was being stressed in a floated Mk V Weatherby with my bore sighter. Reference points are one's crosshair and the muzzle that might be separated by 24 to 26 or so inches. I bedded the action without installing any screws (simply placing the fully relaxed barreled action in a thin layer of epoxy at the tang and recoil lug), and there is no longer movement in the bore sighter during tear down or assembly. It also went from golf ball sized groups to cloverleafs (a 257).

Do the same experiment with stocks supporting a forearm pressure point and one really gets a lesson (like 6 or 7 inches at 100 yds). Disassembly and reassembly of such demands that one make a science out of torquing down his action screws if he expects the unit to return to the same point of impact. Such can also generate a bit of upward creep as a barrel warms.

Beings the bore sighter is at the extreme end of one's barrel, it's quite sensitive and indicative of the slightest of movements Also, one does not need to fabricate any sort of jig to keep his instruments and/or rifle components in place.

Such can also easily illustrate the effects of gripping both the barrel and stock with one's forward hand or the effects of sling stresses if one goes that way.

I have a nail driver Anschutz and a buddy that employed the gripped barrel practice couldn't hit ground squirrels with my rifle to save his soul. I, of course, never missed. One look with the bore sighter installed and he could clearly see that it doesn't take much hand pressure at all to put a tiny bit of flex into one's barrel. An inch at 50 yds is more than enough to miss a standing squirrel.

Have a good one,

I have tried this on my CZ's as well as my Bergara B14-R and have noticed improvement with my groups. My CZ's generally like 22-25 in/lbs on both action screws and the Bergara likes 55 in/lbs (the factory setting).

I will shoot 3 shot groups starting at 15 in/lbs and work up to the factory spec in 5 lb increments. Invariably, one setting will have the tightest group and then will adjust by 1 lb increments in that range for fine tuning. Usually it's around 20-25 in/lbs for the CZ's. This works on all of their models but more so on the wood stock variants. I haven't pillar bedded any of these rifles. None have had the action screws work loose at this time.

I’ve been doing this on my rimfire rifles for about 4 years now, and funny that nobody has mentioned a gun liking the front action screw at 27 in pounds and the rear screw at 15 in pounds 😂 because that’s what most of mine are like

This conversation brings to mind a conversation I had with my late friends Al and Roger Biesen. I asked both of them, chatting in Al’s basement shop in Spokane, about their preferred torque on action screws. Both were emphatic about it…that it doesn’t matter if the rifle is bedded right.

Both were fans of a “just make them tight” technique and reemphasized that it’s much ado about nothing in a properly built stock. And having owned several of their rifles that were tack drivers, their comments carried weight.