Proper bedding job

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PEI Rob

New member
So often I see the word "proper" when referring to a bedding job but never any tips, besides the always amusing alternative release agents of course. We have covered chambering methods in great detail, more than once. For anyone interested in learning, chambering should be just a matter of practical at this point. What makes a proper bedding job?

Cheers,
Rob
 
Relaese Agent

The use of a quality Release Agent will prevent you from accidently glueing your action in permanently. I'll just shoot it until I have to remove the trigger.
 
A proper bedding job is one that allows the action to lay in the stock somewhat stress free. Somewhat stress free in that any time the guard screws are tightened, they are going to put some stress on the receiver at the trigger guard screws. My "proper" bedding job uses stainless steel pillars made from take off 416 stainless rifle barrels if weight isn't an issue. The sole purpose of the pillars is to prevent the bedding job from being ruined by over zealous guard screw tightening. To check to make sure that the bedding is stress free, you use a dial indicator between the barrel and forend and tighten and loosen each guard screw one at a time. If there is more than .002" movement between the barrel and forend, then the bedding isn't stress free. .002" movement or less between the barrel and forend, translates into a lot less actual movement between the action and stock. If actually measured where the action meets the stock it would probably be down into the .000?" area of actual movement between the action and stock. If the action has a recoil lug, I mill out underneath, sides and front of the recoil lug. The only purpose of the recoil lug is to keep the action from moving rearward in the stock. It's not to keep the action from torquing during a shot. On a round action, you should be able to remove the guard screws, turn the rifle upside down and have the barreled action fall out of the stock. A flat bottom action like a Stolle Panda won't do this as there is enough friction between the sides of the action and the stock to keep the barreled action in the stock. For 1/4" guard screws, I drill out the pillars to 5/16" which allows a 1/16" total clearance between the guard screws and the inside of the pillar. The amount of clearance isn't important as long as there is clearance that doesn't let the guard screws touch the inside of the pillars. For a pillar such as the front guard screw pillar, I ream the top of the pillar with a countersink that is angled the same as the guard screw head to let the screw head go down below the top of the pillar. Then ream the pillar with a .265" reamer. Turn the pillar around in the lathe and drill out the pillar to 5/16" to a point within about a 1/4" of where the guard screw head will sit. This allows the guard screw to hold the pillar to the action and after it's bedded in, will hold the action to the stock.

As to clearances, you also need to check that there is clearance between the trigger, bolt handle, magazine parts and the stock. None of those parts should be rubbing on the stock.

If a rifle has more than .002" movement between the barrel and forend, it will not shoot to it's potential. Check for this amount of movement or less after you bed the rifle before any magazine parts are installed. Then check again when the rifle is completely assembled. If you have that amount of movement or less when you have a stripped barreled action in the stock and you don't have that amount of movement when all the parts are back on the rifle, then you'll need to check for parts rubbing against the stock, magazine parts too long and things like that.

In the Bob Pease articles that he wrote back in the 70's or early 80's, he said you could check for a stress free bedding job by loosing off the front guard screw and shooting a shot, tighten it back, shoot a shot, loosen the rear guard screw, shoot a shot, tighten it back and shoot a shot. The results on target should look like a group with a good bedding job and won't with a bad bedding job. It's simpler to just use a dial indicator between barrel and forend to check for the bedding job being stress free.

Hope that helps you out and as with just about everything in riflesmithing, there are more than one way to go about something. The only place that makes a difference is how the finished rifle shoots on target.
 
Thanks Mike.

I was also wondering about parallelism. In a perfect world the stock is inletted parallel and the barelled action is also straight. Some BR stocks available to use are fairly cheap and not all that perfect. I'm wondering how you guys set up for these. Do they need to be dead square to the recoil lug? Normally I wrap the barrel to center in the channel but somehow this doesn't seem up to BR standards. Do you guys worry about tracking enough to correct for it regularly? Oh yes, are we all leaving about .020" of bedding on top of the pillars?
 
My pillars are squared off where they make contact with the action. They aren't shaped to conform to the action. I used to shape them to the action, but haven't seen that it made any difference. I screw the pillars tight to the action where the pillars make contact with the action letting bedding compound make the contour of the action. It's been a long time since I contoured a pillar to match the shape of the action. There is bedding compound between the pillar and the receiver from the center out, but not at the center where it metal of the pillar to metal of the receiver.
 
Funny.

I've yet to bed a bench rest barreled action parallel to the showline of the stock.

Try adding about 1.5 degrees of elevation once. It sure seems to track in the bag a whole lot nicer.:D
 
Mike
How much clearance do you leave around your pillows?
Thanks

Glenn
 
Rob,
As Mike said, a proper bedding job allows the receiver to sit "stress free" in the bed of the stock. While there is always some stress induced by screw tighteneing, distortion should be minimal.
I favor the use of fiberglass pillars but, if metal is to be used, I prefer steel over aluminum. I will now set forth my method for glass bedding a typical Remington 700 hunting or varmint rifle with wood stock with glass pillars.
1. Remove the trigger and bolt stop from the action.
2. Wash the action with Varsol
3. Prepare the stock by drilling a 5/8 inch hole from the top of the receiver mortise to within about 1/8 inch of the bottom at each gurd screw location (I used to drill right through but leaving a thin wafer of wood at the bottom made for less compound on my shoes!).
4. Remove wood between the drilled hole and the recoil lug mortis to a depth equal to the bottom of the mortise. Also remove wood to within about 1/32" of the top edge at the receiver ring area. Bedding of the full length of the receiver is optional. If you are going to bed full length, remove about 1/8" of wood all along the bed; leaving the same narrow margin at the top edge.
5. Put tape around the barrel at the forend tip and just ahead of the recoil lug until the barreled action sits at the proper attitude and depth. I believe in setting barreled actions halfway into the stock. It may not have any effect on performance but it is the RIGHT way to do it!
6. Tape the front, sides, and bottom of the recoil lug (I use two layers of electrician's tape)
7. put a single layer of masking tape over the trigger pin holes.
8. (Optional but preferred) Apply a layer of masking tape to the receiver from the front of the magazine well to the rear of the trigger cutout
9. Recheck fit of barreled action in stock (Important!)
10. Apply release agent ( I like paste wax thinned with varsol) to the receiver, trigger guard and floorplate, inside of the magazine cutout in the stock, the outside of the stock, and (very important!) the screws. It doesn't hurt to apply the wax anyplace you don't want the epoxy to stick even if you don't intend to bed in that area (eg. the length of the barrel, the top of the receiver, etc.). fill the guard screw holes with wax.
11. Install bottom metal and screws into the stock. Keep them in place with masking tape.
12. Mix bedding compound. I use Acraglass liquid (red box). Mix thoroughly and add enough thickener (fiberglass floc) to make it only moderately runny.
13. Spread compound over the area to be bedded and into the holes for the pillars enough to coat all surfaces.
14. add some more floc to the mix to where it is barely runny
15. fill the holes for the pillars. Be sure and poke the mix down into the holes and around the screws so as to eliminate any voids in the mixture.
16. Add more floc to where the mixture is quite stiff ( 75 degree butter?).
17. Apply compound to the entire stock mortise. Use enough that there will be no voids.
18. Apply a dab of compound to the receiver right behind the recoil lug. This ensures there is no air trapped in this area.
19. Set the barreled action into the stock. Start the screws into their holes
20. Turn screws in just enough that they contact their seats WITHOUT pulling down on the receiver. Their purpose in life is to holt the bottom metal in place and align the bottom metal with the barreled action.
21. Remove most excess compound which has squeezed out.
22. Set rifle aside to set. I set the rifle on a cardboard box with notches cut in it for the purpose. Leave it be for a day.
23. Remove screws (this is easily done providing you have followed the instructions in (10) above.
24. Make sure there is no overflow of compound mechanically locking the receiver in place.
25. Pop barrelled action out of stock.
26 Clean up stock and barreled action and re-assemble.
There you have it. This will produce a very sound bed for most purposes but it can be improved upon.
The Acraglas has some shrinkage when it sets up so that the bed may not be perfectly level on the surface. So, in order to produce an even better bed, one has to scape the surface of the bed and chip out the recoil lug mortice a bit, then bed again.
Variations.
The use of pillars is popular and effective. Like, Mike, I prefer steel. I cut the pillars flat and checker the tops.
The holes are drilled clear through for the pillars and the pillars made about 20 thou under sized to provide room for the epoxy. The pillars are screwed tight to the receiver and the receviver is bedded as before but without the bottom metal. The bottom metal is bedded over the pillars afterward.
Different actions call for different treatment but the basics are the same. Stress free, solid atachment is the goal regardless of action type. If an action is to be glued in, it still needs to be glued into a solid, stress free bed.
On Savage rifles, I like to float the tang entirely.
The Acraglass liquid is a bit of a pain to work with but it is very strong and seems impervious to any solvents. Also there is no apparent degradation of the stuff over time. Although I sometimes feel I can achieve a nicer surface with other compounds, I still think the original Acraglas is tops for producing a solid foundation. Great glue too.
I see little point in casting a glass pillar in a Mc Millan stock. It`s already pretty solid.
Hope this is informative for those who want it. Regards, Bill
 
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