Bedding an action to the stock

B

Bob Boldman

Guest
Hi guys, I am preparing to do my first pillar and full bedding on a rifle. My question, with the action locked down to the pillars and the trigger guard should there be a little wiggle room for bedding material or should I shorten the pillars for a solid fit? My thinking is to have a little room for the bedding material.
Your help is much appreciated.
Bob
 
Function of the pillars

One theory, mine at least, is that the pillars exist to keep the stock material from compressing. When bedding, when you tighten the action screws so the action touches the pillars, you then back off 1/2 turn or so on the screws so the bedding material flows back in a bit. Some even recommend leaving a little skim over the pillars.

I think it's a judgement call and go with what shoots best for you. I personally feel like having the action hard against the pillars is not good for accuracy. Others may differ.
 
Dusty Stevens said:
Which is why most good pillars have the tops cut away and only have 2 small points of contact
Look at the picture of this perfect bedding job by long rifles

http://forum.accurateshooter.com/index.php?topic=3842271.0
Click to expand...

The Chad do do nice work don't he :)


BTW, it is my opinion that to get a good bedding job one must set up for NO/nada/zero screw pressure...... the only thing holding the action into the stock whilst the bedding sets should be gravity. The only "screws" should be guide screws whose only function is alignment. The barreled action must be in stress-free suspension while the 'glas cures.



opinionby


al
 
There are more than one way to install pillars. A long time ago, someone who has been at the center of benchrest for decades told me that when pillars were first used, that they figured out that if metal pillars were used, that they got better results with a thin coat of bedding over their tops. Also, some fellows may not have figured out that when a rifle, with a floated barrel, is in firing position, that the force on the tang of the action is in the upward direction, which means that the bedding of the trigger guard can make more difference than they might imagine. The weight of the barrel is pulling up on the back of the trigger guard. As far as installing pillars goes, if you do that as a separate step, with thin spacers between them and the action and trigger guard, as well as between the action and the stock, you can go back and bed the action, and over the top of the pillars, and then the trigger guard the same way. When you install the pillars, if you wrap your guide screws with something, the pillars will be centered on the screws, with an even gap all around. Another way to accomplish the same thing is to make the pillars with a close fit to the screws, and then drill them out at the end, with a piloted drill. It is important that the fit between the pillars and the stock be loose enough so that there is room for the action and pillars to be positioned stress free, and so that the trigger can be centered in its mortise, and the guard when the job is finished. Another benefit of installing the pillars first is that you can use an adhesive that may not be the best for bedding, but is better for bonding the pillars to the stock. Because aluminum oxide does not make for a very strong bond with epoxy, you may want to rough up the outside of the pillars just before installing them, as the last step before coating them and the holes that they go in with epoxy. Grooving pillars can also help by providing a mechanical lock, and increasing area.
 
Questions for those with opinions...

If a pillar is in contact with the action, and the screw torque cannot compress the pillar, what does the rest of the bedding surfaces do for the bedding job?

Lets say we have an aluminum pillar that expands and contracts with temperature at a different rate than the stock material, in a solid pillar to action fit, what effect would a large temperature change have on the bedding job?
 
Bob,

I agree with Dusty...gotta give the bedding somewhere to go. I typically machine out a goodly portion of the tang and the front action screw area, the theory being that there is a thick chunk of bedding material there that won't crack/crumble like a thin layer might. I leave my pillars, which are roughed up/grooved/knurled on the OD, a bit long and screw them to the action. I'll then wrap a piece of 10 mil tape on the front and rear of the action. The tape serves to hold the action up out of the inletting a wee bit. I then 5 minute epoxy the pillars and set everything in the stock. A wrap or two of masking tape over the tang and front action screw areas holds everything in place. Of course there is a liberal application of release agent to stuff I don't want 5 minute epoxy sticking to. After everything sets up and is taken apart, cleaned, etc., I have an action that sits on two points...the two pillars...and doesn't touch the stock. When you tighten up the action screws, they just kinda go "thunk", like a good barrel to action fit. Then I Marine Tex the inletting and the action, drop it in place, and tighten up my slave screws until they just go "thunk", and go drink beer ( Firestone DBA...the official bedding beer). I usually get Zip Point Sh!t movement using this method when checked with an indicator. The extra length on the pillars sticks out the bottom and is machined away. There are a ton of other ways, but this one seems to work for me.

I remember reading a statement by George Kelbly that they could never get their rifles to shoot if the action was touching the pillar. George is talking benchrest rifles. I'm building/bedding live varmint and deer rifles, and they seem to shoot good for me and those I've done for others. But...Ol' George has bedded more rifles in a week than I'll bed in a lifetime, and I generally pay attention to people such as him when they speak. As such, I intend to machine up some pillars like Chad Dixon uses...got little tabs on either side of the thru hole that get machined off after the bedding job so the action just touches bedding, and not pillar. Genius idea...and Dixon's bedding jobs always look fantastic.

FWIW,
Justin
 
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