Pillar to mounting bolt clearance?

[Keith Glasscock]

Need some opinions from the pros....

How much clearance is enough, or too much, or too little for action pillars?

I have 3 pillar bedded rifles. 2 I did (and have a significant clearance around the bolts) and 1 that had the pillars molded in when the stock was built (pretty tight fit on the bolts and is only skim-bedded with acra-glass).

All 3 shoot darn well, but the last one will need the bedding replaced soon. Should I open the pillars up when I rebed?

I intend to leave the pillars in the stock and just grind out and replace the bedding compound (and make it a bit thicker as well). Any advice on the best way to get an optimal, no-stress result?

Thanks,
Keith

 

[Preacher]

You really don't want the bolts hitting the inside of the pillars, they need the clearance..
Tape the barrel where it hits at the front of the stock, until you have the action setting exactly where you want it. Then do the bedding, and hold it lightly in place till it sets up with tape just ahead of the receiver.
Clean up the over runs before it sets up, and all will be good.....

 

[BoydAllen]

If the action screws were touching inside the pillars, I don't think that you would be getting the accuracy that you report, but any time that you change something, there is a chance that you can go from close to touching. I believe that building in a controlled amount of clearance is the best approach, mainly because drills may not stay centered as you open up pillars. If I were trying to drill out pillars today, I think that I would get a hold of a piloted drill.

 

[Keith Glasscock]

This rifle shoots very well indeed. I have bettered the F/TR NR at both 300 and 600 during practice, so I know that the accuracy is there. All I have to do is my part at a registered match. Unfortunately, the Acraglass is starting to look funky. I'm going to do it with Devcon 1011 like my other rifles.

How much larger than the OD of the bolt would you go? Right now, I have about .030" total (.015 per side) and while I don't have any rub marks, I suspect that it touches. The only limit would be to maintain a reasonable contact surface for the head of the bolt and I can do something about that if it's a problem too.

 

[BoydAllen]

...just enough that you are confident that you have clearance.... If you want to be sure, put some scotch tape on the screws and see if they drag when you are screwing them in, prior to tightening. If you don't feel any drag you can pull them one at a time, remove the tape, and you should be good to go...don't you think?

 

[Keith Glasscock]

Makes sense to me. Maybe I should try that before I do anything else. It maight be good the way it is....

When I rebed, I know I don't want to be torquing the bolts down. Instead, I want the action floating on a puddle of bedding material. Should I make some long headless bolts for the pillars (since they are solidly mounted in the stock) and just use them as alignment rods? Thoughts?

 

[Preacher]

Headless bolts wrapped with enough tape to help them center is a good idea.

 

[BoydAllen]

If you look at erniethegunsmith.com you may come away with some good ideas. He has some epoxy washers that I think that he calls bed heads (or something like that) It seems to me that they might be helpful for a stress free skim coat. Personally, if I had a rifle that was shooting as well as yours evidently is, I would wait for it to stop performing before "fixing" it. Ugly is as ugly does.

 

[Keith Glasscock]

That has been one of my fears - messing up a good shooting rifle.

I'm getting ready to have the next barrel done and was thinking about a little better bedding to help support the new barrel (heavy palma profile). Right now, I'm shooting a straight-taper 26" that has a lot less leverage on the action (shorter and weighs ~ 1.3 lbs less).

 

[BoydAllen]

I would shoot the new barrel first.

 

[Keith Glasscock]

It isn't going to hurt anything is it?

Might just save me some work....

 

[jscandale]

Whenever I pillar bed a rifle, assuming that the action screws are 1/4", I always set up and complete the bedding and let the bedding dry. Once the bedding is complete and dry, the last step is to run a letter F drill through the pillars. Letter F is .257" which allows just enough clearance between the bolt and pillar wall.

JS