Trouble Getting Stress Free Bedding

[TuckerJ]

Last winter I pillar bedded a 40X (722 based) .22lr. I left a small bit of wood at the rear of the tang, and wrapped layers of tape around the barrel near the forend to set the height. I 1st glued in the pillars, and then later bedded it. I left the pillars short on top and bedded over them. Wrapped long bolts with tape to locate the action and create space in the pillars. Taped the front, sides, and bottom of the recoil lug. I seated the action into the bedding material with hand pressure, and then wrapped masking tape just ahead of the barrel to hold everything in place. Used MarineTex Gray and when I removed the barreled action it looked absolutely beautiful. I used a file and Dremel to relieve material and chamfer all screw holes, top of recoil lug slot etc so there were no ridges.

I was very surprised when I had about .01" of movement when I loosened the front screw. When I loosen the front screw I think the barrel is rising away from the stock. The rifle didn't shoot that great either. I tried grinding out more bedding to make more clearance around trigger pins, front of lug etc with no improvement.

Ground off a layer of bedding and tried it again. This time using surgical tubing to secure the action while it cured. SAME RESULT.

The picture is how the bedding looked after my 1st run at it. I know pretty bedding doesn't mean good bedding...

I put a single layer of masking tape over the tang, and my movement shrunk to around .0015-.002. Rifle shoots well like this but of course I don't want to leave this as a permanent solution.

I assume I have a lot spot in the tang, or maybe a high spot somewhere just ahead of the tang.

Any ideas what I did wrong and how I can get this right on my 3rd attempt? I don't feel like I used excessive pressure when holding the action down into the stock. I've heard of some that let just the weight of the barreled action sit in the bedding but the Marinetex seemed stiff enough to spring it back up when I did this.

 

[Will Henry]

The wrap of masking tape ahead of the action was a mistake. Surgical tubing, ditto. When you put the barreled action into the bedding, push in down by hand, with the screws in place for alignment. Then, you can turn the screws in, just until they contact. You can tell by the movement of the excess epoxy, just when the screws are starting to deflect the action. Turn in until deflection starts, then back off. Set the stock up level and let it cure with nothing but gravity pushing down on the barreled action. I like to use masking tape around the barrel, at the fore end tip, and just ahead of the action, to level the action in the stock. One can then use tape or tubing over these spots to hold things in place if he feels the need. WH

 

[10XSHOOTER]

Put a guide pin in your rear screw hole. Use a bedding screw in the front screw hole and tighten down. let the action float in the bedding. I make barrel rings of Delron to center the front of the barrel in the barrel channel. tight slip fit on barrel and turned to barrel channel diameter.
No tape or rubber bands anywhere on the action. Just the front bedding screw

 

[tobnpr]

Surgical tubing, ditto

Respectfully disagree
Surgical tubing provides an even distributed clamping force across the length of the action rather than point loads induced by screws IMO

That said, I do not set pillars low- I believe that is the point of failure here. You can't support the action at the tang and barrel channel and then clamp it- this obviously will induce a bending moment as the action screws are tightened.
With the receiver bottomed out on pillars set at the correct height there's simply no way the action can bend/flex.

 

[Will Henry]

I was afraid I wasn't being clear enough and that is indeed the case. There should be NO force pulling the action down other than gravity.
As far as bedding over the pillars is concerned, I've done it both ways and both ways can work. If bedding over them, I checker the tops of the pillars and sandblast them I install them with a fifty thou washer between them and the action. I then bed over top. WH

 

[BuffaloBill]

I concur with Will. Use only gravity as the compound cures. In my experience measured movement with rifle vertical, is less than .001”.

 

[TuckerJ]

I like the sounds of just letting gravity do the work. Is there anything special I need to do to keep the action seated at the proper depth? Previously when I've seated the action with my hands and then released the pressure, I could see the tang rise back up slightly. I was worried this could make some low spots in the bedding if the metal lifts back up.

I'd have almost thought it would be easier to impart more torque/stress with the action screws than lighter wraps of tape of tubing, even if I was conscious to be very light on the screws.

 

[ArtinNC]

I always thought that you didn't want the pillars touching the action because of bedding material shrink over time .The action will only be setting on the pillars and not the bedding .

 

[Will Henry]

The reason the tang lifted back up was because there was something in front of that position which was causing it to do so..
when preparing to bed, before putting realease agent on the action, check and recheck to be certain the barreled action sits as you intend it to. In your case, you wanted the action to sit on the tang and the tape on the barrel. If the tang doesn't contact as intended, there is something holding it up.
I should mention, things can deflect surprisingly easily, where the stock is held in the vise can make a difference.
In the case of this rifle though, I suspect there was a spot, somewhere in the middle of the action, which was a little too high. If you had just used the gravity method, the action would have contacted at the pillars and at this high spot. Since you added pressure ahead of the high spot, that spot became the fulcrum which lifted the tang up. When the pressure was released, the tang went back down and lifted the front, with the high spot being taken out of the picture. WH

 

[tobnpr]

I always thought that you didn't want the pillars touching the action because of bedding material shrink over time .The action will only be setting on the pillars and not the bedding .

Any of the multitude of epoxies suitable for bedding have inconsequential shrinkage. Using flat pillars always results in a thin layer of epoxy over them on round receivers anyway.
Besides, if the bedding does shrink it's not going to be isolated to the area around the pillars, right?
You'd have (immeasurable) gaps on bottom and sides the full length of the action.

I should mention, things can deflect surprisingly easily, where the stock is held in the vise can make a difference.

I'm thinking I might have better success going back to the one-step method (pillars and receiver together) by sticking the barrel in the vise (receiver upside down), and pressing the stock down onto the receiver.

 

[TuckerJ]

The reason the tang lifted back up was because there was something in front of that position which was causing it to do so..
when preparing to bed, before putting realease agent on the action, check and recheck to be certain the barreled action sits as you intend it to. In your case, you wanted the action to sit on the tang and the tape on the barrel. If the tang doesn't contact as intended, there is something holding it up.
I should mention, things can deflect surprisingly easily, where the stock is held in the vise can make a difference.
In the case of this rifle though, I suspect there was a spot, somewhere in the middle of the action, which was a little too high. If you had just used the gravity method, the action would have contacted at the pillars and at this high spot. Since you added pressure ahead of the high spot, that spot became the fulcrum which lifted the tang up. When the pressure was released, the tang went back down and lifted the front, with the high spot being taken out of the picture. WH

Thank you for the response. It would be hard for me to believe anything contacted the action as I relieved quite a bit of wood before bedding EXCEPT for the reveal at the top of the stock. I tried to keep a minimal gap there. Maybe that bound up somewhere. I did drop the barreled receiver in multiple times and it had no binding etc. I was thinking just the stiffness of the bedding was causing some rebound if it built up some pressure under the action. And maybe it did - maybe having less of a gap at the top edge of the stock made it hard to push excess bedding out. I had to press pretty firmly to seat the barreled action into the bedding material.

I have some good things to consider and re evaluate before I bed for the 3rd time.

 

[243winxb]

Remove middle bedding & pillars, below action, not touching. Place shim under barrel towards muzzle inch or two in front of lug. , to center barrel/action in stock. Apply bedding. Put release agent on stock screws. Make screws just snug, not tight.
3 points of contact. Action just behind the lug, rear of lug & tang area.

 

[243winxb]

to do to keep the action seated at the proper depth?

make barrel rings of Delron to center the front of the barrel in the barrel channel. tight slip fit on barrel and turned to barrel channel diameter.

Place shim under *AROUND* barrel towards muzzle inch or two in front of lug. , to center barrel/action in stock.

Remove shim after bedding has cured

 

[TuckerJ]

Remove middle bedding & pillars, below action, not touching. Place shim under barrel towards muzzle inch or two in front of lug. , to center barrel/action in stock. Apply bedding. Put release agent on stock screws. Make screws just snug, not tight.
3 points of contact. Action just behind the lug, rear of lug & tang area.
View attachment 1737003

I did consider doing something along those lines. It seemed like cheating though it may work. I may consider doing something like that but I also feel like I should be able to do this correctly the "right" way. I might still think about doing something like that though.

 

[LVLAaron]

I dont use shims or anything to hold anything in place. I find the balance point of the barreled action. Wrap tape around the barrel to get it the height it should be. Make sure everything fits. Make sure again. Lay down the glue and press the action in. clean it up. It will sit there where it belongs without any tubing or tape or clamps or whatever.

 

[243winxb]

Wrap tape around the barrel to get it the height it should be.

Yes, correct height & centered in the stock channel. What ever works, works.

 

[AlNyhus]

TuckerJ, just a couple thoughts on your bedding project. First off...good job on locating the issue (low tang bedding). That likely comes from two things that happened with the bedding process.

1- Taping the barrel to center it is a good idea. But when you tape the barrel at the end of the fore end...that's the leverage point where the barrel may pivot on. Depending on the barrel length and weight, this can act to lift the tang.

2- Surgical tubing, being round, always has an element of stretch in it...no matter how tight you get it.

The combination of those two things are likey the cause of the problem. The tang 'lifted' slightly during the curing process, which caused the bedding under the tang to be low. Your experiment of the tape under the receiver tang reducing the movement confirms that.

If you're going to support the barrel in that way, the barrelled action needs to be secured down into the stock better during curing. C-clamps, etc. can do this. A better solution is to support the barrelled action at it's natural balance point with a narrow wrap of tape or an 'o' ring. Then the barrelled action won't want to drop down at the muzzle. Once you do that, you don't need to get as aggressive with holding it in the stock. A few wraps of tape or a flat tourniquet (not surgical tubing) works.

As to your situation, if it was here.... I'd rough up the tang bedding, put a dab of new bedding on the area and bolt it together with the action screws. Check it and see what it shows.

For what it's worth................ -Al

 

[Hi-NV Shooter]

Interesting about not using any wrap around the action when bedding. I always used electrical tape to hold the action in place at the tang, front and near or at the port. once cured the action can sit without screws and not move.
for this 40X in question seems to me the recoil lug should prevent any movement if it was bedded.

Lee

 

[LVLAaron]

I like the o-ring!

 

[AlNyhus]

I like the o-ring!

Another great tip from Dave Tooley.