Free floating a cz 452 varmint?

[njjessee]

Curious - is there a technique for bedding a rifle with a single action screw w/ barrel lug that works consistently between rifles? For my CZ452 silhouette, I used a set screw to lock the barrel lug in place, then pillar bedded both the action bolt and barrel lug bolt. The barrel lug is also set in bedding as well. The barrel is floated starting about an inch in front of the barrel lug. I'm really thinking the rifle should shoot better than it does, so perhaps some experimentation is in order.

Jason - could you describe Neil Johnson's technique?

I'd like to hear what Evelio would advise, if he would be kind enough to do so.

Noah

[BlauBear]

Curious - is there a technique for bedding a rifle with a single action screw w/ barrel lug that works consistently between rifles? For my CZ452 silhouette, I used a set screw to lock the barrel lug in place, then pillar bedded both the action bolt and barrel lug bolt. The barrel lug is also set in bedding as well. The barrel is floated starting about an inch in front of the barrel lug. I'm really thinking the rifle should shoot better than it does, so perhaps some experimentation is in order.

Jason - could you describe Neil Johnson's technique?

I'd like to hear what Evelio would advise, if he would be kind enough to do so.

Noah

Noah, my technique was identical except that the barrel lug was allowed to float. I did use a single layer of electrical tape around the barrel lug to maintain a small gap between it and the bedding.

[austin870a]

By bedding you are seeking extreme consistency of pressure between the action/barrel and stock. Because of all the inconsistencies involving the single action screw w/ barrel lug the most successful people forget the barrel lug completely and drill a second action screw in the action. They pillar bed it just like you would any normal gun with two action screws leaving the barrel free floated. When you leave the forward lug triangulation it can cause significant inconsistency defeating the purpose of the bedding job.

Many Varmints shoot worse after being bedded if the forward lug is used as the second action screw for stability as it is designed. If you leave off the lug, the single action screw by itself is very poor at stabilizing the action/barrel. The barrel is quite heavy in relation and the single action screw so far away cannot consistently stabilize the barrel. This is especially true if the barrel is floated. CZ says the forward barrel lug was simply not designed to have a free floated barrel and this makes sense.

You can have anything work or not work on the Varmint concerning the barrel lug, however consistency is lacking to say the least. That is why if you reach a point in your experimentation where the gun shoots well... stop helping it.

[BlauBear]

We can agree that a barrel lug makes a terrible action bolt and a second action bolt in the receiver sounds like a good idea. I would love to know CZ's explanation for the arrangement, but to my knowledge they haven't shared that yet so we're left to guess "What the heck were they thinking?" Because of the barrel lugs' mass and the floating, milled barrel slot my guess is that it's intended as a harmonic dampener / recoil lug, not an action screw.

My testing on one rifle got better results with the barrel lug in place and floating with a small gap between lug and bedding, the same way I would bed any recoil lug.

[austin870a]

I agree and ask why on a 452? The single action screw cannot stabilize the barrel when free floated. When the barrel is free floated the lug is forced to become more of a very poor second action screw. What complicates the situation is the lug is always trying to act like a harmonic dampener of inconsistent and varying degrees depending on each individual gun. Sometimes the added harmonics are positive and other times negative. When removed the lug leaves the barrel unstable. I believe it was designed to have the barrel channel support the barrel weight while the lug acted only as a harmonic tuner. Unfortunately, the consistency of the 452 barrel channel routing leaves something to be desired and forces owners into modifications.

I believe the floating barrel lug appears to have been designed for use on the old Brno position shooting rimfire rifles as it goes decades before the CZ 452. I believe the design worked well for the old Brno’s because with a 26 to 30 inch heavy barrel and heavy open sites the conventional 2 action screws at the action had challenges stabilizing the last half of the barrel. The Brno had a large barrel channel that was not free floated. I believe the 452 design was marketed off the success of the Brno.

I still like the Varmint. It is just very different.

[BlauBear]

Thank you for a very plausible explanation!

[Jason]

Plausible, but not necessarily true for every gun. The pillar-bedded (only one pillar) Varmint shoots better now. Seems to shoot best with 42in/lbs of torque. Not sure if that will be with all ammo, but with the Eley Club Extra EPS (orange box) that I got from Cathy a year or two ago that seems to be the combo. The trigger and balance is still a bit inferior to the rebarreled 1712 but that CZ really shoots now. When I get time l'll try to remember to pull the action out of the stock and take some pictures of the bedding.

[Senator vitaman]

And yes, always sight a rifle in after any adjustment, and particularly after taking it out of the stock.

Should be even more essential with this kind of modification

[Evelio Mc Donald]

Well finally, I found some time to do some postings. I have done 3 CZ 452 in Pharr stocks, on them, I removed the barrel lug completly, bedded the whole action with a pillar, and also bedded about 3" of the barrel in front of the action, and at the same time bedded about 1/2" of the barrel at the tip of the fore end, mainly to give extra support to the barrel, all 3 shot better than before. I am not crazy about one screw holding eveything together, but when properly bedded, and torqued, it is enought to keep everything in place.
The same action in the Scout model with the short barrel, don't have the barrel lug, and only one screw holding the whole thing together.
I also had the pleasure to work on a couple of Schultz & Larsen made in 1928, and a BRNO, all 3 position guns, and all 3 had barrel lugs on them, looks like the European design for long barreled guns was copied by CZ to some extend.
In my opinion if the rifle is handled with care, and not used as a baseball bat, one screw should be able to keep everything in place.
Evelio.

[njjessee]

Evelio - do you have a recommendation for bedding the CZ452 American? Mainly interested in how to handle the lug on the back of the receiver. Also, have you ever replaced barrels on CZ452's with something like a Lilja or other?

Thanks,

Noah

[Shandy]

I glued my CZ American's rear lug to the action using Devcon Plastic Steel (the same stuff I did the bedding job with). I just put a small amount in the dove tail to fill the void and then screwed the action into the stock so that it pulled the lug down into the natural position for it when in the stock. I did this before bedding and it locked up the lug in the correct place before i proceeded with the bedding job.

I then worked carefully to install pillars for the front and rear screw, taking care to get the length right. I then relieved wood in various locations to create space for the bedding compound and made dams with plasticine (horrible, waxy stuff-I'd look for something different), removed the trigger and mag housing and then bedded the action with Devcon. I bedded around the rear recoil lug, provided a bedding surface for the tang, along the action around the front pillar and then all the way up to 1 inch in front of the action. I then cleaned up various bits with a dremel or sand paper to relieve the holes again for the mag housing and trigger.

It all went well and the rifle continued to shoot very well. Of note I noticed that I could take it out of the stock and replace it with no (significant) change in POI regardless of screw torque.

I've since sold the rifle so can't show pics, I now have a Sako Finnfire that shoots very well indeed but the action moves in the stock so I'll end up bedding this one too.

Have fun.