I have a stock wrecker and I don;t know what to do about it

[Whiterabbit]

Here's the issue:

http://castboolits.gunloads.com/attachment.php?attachmentid=113394&d=1407896333
(images stopped working in the threads for me)

Anyways, the image shows an inlet tang. CZ550 safari magnum. This is stock #2, and here's the issue: I believe that the wood is compressing under recoil. Specifically, around the mag box. This means that no matter HOW good the recoil lug is, the tang and bolt lever and even the triggerguard maybe comes slamming back into the stock under recoil.

On the first stock, I had at LEAST triple the clearance at the tang. It still cracked there. It also cracked at the bolt lever, and there's lots of clearance there too.

So, I'm thinking clearance is not the solution here.

Trouble is, I don't know what the solution is. Bed the tang? Bed the tang with clearance? Glass epoxy could help stabilize/plasticize the stock around the tang area, but I don't know if that will amount to enough support to prevent the wrist from chipping out under recoil.

What do you guys think? How can I prevent the tang and bolt lever from flying back as the mag box wood deforms under recoil?

[knifemaker]

First off, the magazine box should not be touching any wood, especially in the rear of the magazine where the wood would be acting as a secondary recoil lug. I can tell by your questions that you have not glass bedded a rifle or at least a high recoiling rifle. The recoil lug will need to be glass bedded along with the receiver. the tang should also be bedded and clearance left behind the rear of the tang to prevent cracking the stock. More care is needed to bed a heavy recoiling rifle and I would recommend you take it to someone with good experience on bedding rifles. It is not the type of rifle you want to start out with your first bedding job.

[Whiterabbit]

The first stock had a ton of clearance behind the tang and the recoil lug area is to this day hard and strong and rigid. This did not stop the wood from moving under recoil enough for the tang to contact the back and crack. I can bed the tang with clearance in the back. How much do you recommend? .01"? .1"? .25"? Because I was approaching .1" and it wasn't enough to stop the tang from cracking the stock

http://castboolits.gunloads.com/attachment.php?attachmentid=106865&d=1401765317

So is that the best policy in this case? just keep carving and carving and carving out material from behind the tang?

[Mooseman]

The receiver and Recoil lug in this case have to be bedded so the receiver cannot recoil backwards impacting the tang. I Bed them tight with the tang in tight so it cannot impact the stock because the screws arent designed to hold rear movement and impact is more likely to break a stock from my experience with magnum Rifles. You may need to add a recoil block like we discussed in chat..

[leftiye]

Add another recoil lug on the bottom of the barrel. Glass bed, and bolt thru stock if necessary/do it anyway. As stated glass bed receiver/recoil lug. Cross bolt thru stock. Tang can be glass bedded too, but movement to allow tang impacting wrist should not be possible, nor allowed. Some stocks have had cross bolts added behind magazine. As stated previously, magazine shouldn't contact wood.

[elk hunter]

On hard kicking rifles like the 416 Rigby and 458 Win Mag I've done a couple of different things. I've added another recoil lug under the barrel and glass bedded it and I've made up an aluminum block that the recoil lug fits into and glass bedded it into the stock. The aluminum block was about two inches long and the width of the recoil lug. I cut horizontal grooves in it and the stock so the glass had some extra purchase. So far none of the rifles I've built this way, six of them, have had an issue.

[nekshot]

reading this is making my shoulder hurt! The only real hard kicker I glassed I made a sloppy fit of whole action and then set it into a pile of accra gel, put some masking tape on sides of magazine but it all is basically one piece glass front to back and it never cracked.

[Elkins45]

I would glass bed the tang. I do that to every rifle I bed regardless, because it promotes rigidity of the action.

[Nobade]

Normally those 550 magnums have a barrel mounted recoil lug in addition to the receiver. I have gotten several in the shop with broken stocks, and I will add cross bolts if not already there (early ones didn't have them) and epoxy bed the receiver and forward recoil lug. I bed its attaching steel part solidly into the forend. Do leave clearance in the rear, anywhere the receiver could act as a wedge and split the stock. So far I've never had one break after doing this to it. Oh, make sure the screw holes are big enough and the screws can't touch the stock at all. You don't want them acting as a recoil surface.

-Nobade

[waksupi]

On a CZ, better give yourself a bit of a gap on the back edge of the tang. They are notorious for chipping out wood there.

[Whiterabbit]

How much gap do you suggest, and would you recommend bedding the back too just in case the gap just isnt big enough, to toughen up the area as a guard against splitting? I think that is where i am at this point.

[fouronesix]

That relief around the rear of the tang was and is common for many wood stocked rifles, including some military rifles. Once the recoil lug (s) contact surfaces are properly set up for bedding and none of the action screws are making contact with wood, then simply relieve some wood below, along the sides and to the rear of the tang. Also, check the cross bolt (s). I know that sometimes the Europeans place the cross bolt (s) at different locations than their American counterparts. Then bed the lug (s), the lug pad for the main action screw and the tang. After the bedding is completely cured, remove the bbld action and carefully, with a rotary tool, remove some bedding, maybe 1/16"-1/8" inch from around the rear of the tang- remove a complete semicircle of the compound matching the semicircle of the tang end. (You'll have to account for this relief when removing wood around the end of the tang before bedding.) Then if the bbld action moves more than 1/8" (or whatever the clearance is) in the bedded stock and the stock breaks or cracks again….. something is not right with the bedding job or the basic wood is too soft or something. If all else fails... may be time for a good laminated wood or synthetic. :shock:

I'll guarantee an HS Precision stock won't go south with really heavy recoilers, but unfortunately I think they only make one for the CZ in 308 action length. McMillan would be another possibility that probably does have one for the CZ LM action. There should also be good options available for a wood laminate.

[Whiterabbit]

I don't care for laminate or synthetic. After discussing with a couple of the good folks on the board here, the plan is this:

Concentrate on the mag well, and get a solid quantity of bedding material to the sides and front of the mag well. Purpose will be to improve the rigidity of the stock at the mag well to ideally reduce/minimize the tang movement at the back.

I will also re-bed the tang according to your suggestion and give it 1/8" clearance if possible. Though that is an aesthetic mile and a half. No way the action moves 1/8" though.

[waksupi]

I try for around 1/32" gap.

[Ben]

Whiterabbit

The stock may or may not have a cross bolt. For those that don't , I use this technique. I've done 50+ with this method. Some of the stocks held barreled actions chambered for heavy belted magnums. I've NEVER had a stock fail that had the action fully bedded with an internal cross bolt and the recoil lug bedded properly.

Ben

http://i1155.photobucket.com/albums/p545/Ben35049/PICT0001_zps34681476.jpg (http://s1155.photobucket.com/user/Ben35049/media/PICT0001_zps34681476.jpg.html)

http://i1155.photobucket.com/albums/p545/Ben35049/PICT0002_zps3f1f3bf6.jpg (http://s1155.photobucket.com/user/Ben35049/media/PICT0002_zps3f1f3bf6.jpg.html)

http://i1155.photobucket.com/albums/p545/Ben35049/PICT0006_zpsc8ed61cd.jpg (http://s1155.photobucket.com/user/Ben35049/media/PICT0006_zpsc8ed61cd.jpg.html)

http://i1155.photobucket.com/albums/p545/Ben35049/PICT0013_zpsf0dc76fc.jpg (http://s1155.photobucket.com/user/Ben35049/media/PICT0013_zpsf0dc76fc.jpg.html)

http://i1155.photobucket.com/albums/p545/Ben35049/PICT0014_zps4adf38c0.jpg (http://s1155.photobucket.com/user/Ben35049/media/PICT0014_zps4adf38c0.jpg.html)

As has already been pointed out. The mag. box, the guard screws, and the rear tang should not be transferring any recoil to the stock. All recoil should be absorbed by the recoil lug. The fact that the mag. box and tang are moving tell me the recoil lug has not yet been bedded in a satisfactory manner.

[fouronesix]

I will also re-bed the tang according to your suggestion and give it 1/8" clearance if possible. Though that is an aesthetic mile and a half. No way the action moves 1/8" though.

The 1/8" is an extreme. 1/16" is more normal or you can go with near zero. It really doesn't matter as long as it is enough. The better the lug (s) are bedded and the better the wood is in resisting recoil force the smaller the gap can be. But, with really heavy recoil, it can become kinetic in nature. So, a little too much gap- no problem other than being a cosmetic issue. Too little and it's back to a source for potential crack. The other stress placed on a stock is not from recoil alone but from compression by the action screws. May also be a good idea to bed the floor plate and pillar the action screws.

[Uncle R.]

I want to be clear that I'm NOT speaking from experience here - only based on things that I've read over the years.
<
That said - is it possible that the sides of the stock alongside the magazine box are flexing / bowing under recoil ? The full force of recoil is transmitted to the butt through this relatively thin and weak portion of the stock and I've read that it can be an issue if those "sidewalls" are shaped too thin. If the sides are flexing it could allow the action to move rearward under recoil and split the stock even with what should be generous clearance at the tang. If the sidewalls are flexing that action would hammer the stock no matter how perfectly the recoil lug is bedded, or even if there's a second lug on the barrel.
<
Uncle R.

[Whiterabbit]

That's what I have been targeting as a potential root cause, but I'm not sure how I can prove it.

[Nobade]

I dunno, one of those McMillan 550 Safari stocks with the 100% sniper fill (very heavy) might be the ticket for your rifle. They're shaped better than the factory wood one and would stand up to the recoil of your .510 no sweat.

-Nobade

[xs hedspace]

Hardness of the wood varies greatly. If you spread out the area of the recoil lug contact with an aluminum block shaped dovetailish, so that the back of the block is wider, and deeper than the recoil lug, and epoxy that into the stock, it will reduce the setback greatly. Any gap behind the lug is a nono, so epoxy skim coat the block after the epoxy hardens.
Actually, that photo of the epoxy/crossbolt idea looks OK, but would be even stiffer, if the epoxy went clear up to the recoil lug, with no wood in between.

[Ben]

Hardness of the wood varies greatly. If you spread out the area of the recoil lug contact with an aluminum block shaped dovetailish, so that the back of the block is wider, and deeper than the recoil lug, and epoxy that into the stock, it will reduce the setback greatly. Any gap behind the lug is a nono, so epoxy skim coat the block after the epoxy hardens.
Actually, that photo of the epoxy/crossbolt idea looks OK, but would be even stiffer, if the epoxy went clear up to the recoil lug, with no wood in between.

xs hedspace

If you'll look closer, the stock has already been glass bedded prior to me installing the cross bolt.


Ben

[xs hedspace]

Oops, I thought it was a super marblecake walnut stock there, now I see it!

[Geezer in NH]

Caliber?? some need more than just the action recoil points.