FOREND PILLAR BEDDING
Pillar Bedding Forends for best accuracy.
As barrels heat up during firing, they move causing small but very significant changes in their points of contact in the forend barrel channel.
These changes in contact effect the barrel's vibration patterns and thus where the bullet will impact the target from one shot to the next.
It is often absolutely necessary to minimize the effects of these changes to get even acceptable accuracy.
Pillar bedding has proven to be the most reliable bedding method when a forend will be used on barrels other than the one to which it was bedded.
Pillar bedding, like most all tasks associated with the Thompson Center Contender, G2, Encore, Pro Hunter, and Endeavor firearms is quite simple once the concepts and basic steps are laid out.
The concept is very basic.
Metal pillars are epoxied into the forend in such a manner they project up into the barrel channel so that the forend's ONLY contact with the firearm is at the metal pillars.
ALL contact between the forend and the barrel and frame is completely eliminated.
The finished product looks like this:
The barrel channel is widened and deepened to give ample clearance for the barrel, including the area marked in red at the rear of this TC factory walnut forend.
Open the barrel channel IN FRONT OF the tapered part at the rear. Initially, I suggest leaving the tapered part original to help in centering the forend. This is best done with a professional barrel channel rasp sold by Brownells, for example.
I do not recommend sand paper, since it usually results in rounding and wallowing the top edge of the wood making a rather crude, unsightly end product. Keep the top edge clean and sharp.
I suggest at least .020" clearance at all points down the channel. One way to arrive at this is to wrap about 7 to 10 layers of masking tap to the barrel. When the channel is large enough to accept the barrel wrapped in tape, clearance is established.
Pillars should let the screws reach almost to the bottom of the barrel screw holes.
The pillars shown are made from 5/8" aluminum bar stock turned down to about .6" to fit freely in a 5/8" counterbored hole.
Screw heads can be counterbored into the pillar or left flush on top. Grooves are cut into the pillars for epoxy to key into. 7 to 10 layers of tape wrapped around barrel at two points center the barrel in the channel and create "standoff" between the barrel and forend.
The same number of layers of tape on the frame centers the forend "ears" with the frame. Forend ears must not touch the frame and must be opened up also. A fine cut rasp works well.
Counterbore the forend for the pillars.
Counterbores must be deep enough for the forend to fit the barrel and frame without the pillars bottoming out in the counterbored holes. I chose 5/8" material for my pillars for a more rigid contact with the barrel, though smaller pillars as small as 5/16" have been used very successfully. Material does not have to be aluminum. Steel tubing would likely work well also.
Forend ready to bed
Epoxy forend to pillars.
Prep the areas for epoxying, first putting 1 layer of tape under pillars and 1 layer of tape inside barrel channel at each pillar, cutting out the tape over the counterbore holes neatly with a sharp knife. This makes cleanup a lot easier.
Put 1 layer of tape over the screw head ENDS of the pillars to KEEP EPOXY OUT OF SCREW SLOTS ON OFF OF THE SCREW HEAD ENDS OF THE PILLARS. FAILURE TO DO SO MAY MAKE IT MUCH MORE DIFFICULT TO CLEAR EPOXY FROM THE HOLES IN THE FOREND AND ACCESS THE SCREW HEADS.
Put release agent on exposed barrel surfaces to keep stray epoxy from bonding forend to the barrel.
Put one layer of tape around forend screw holes on the outside of the forend to keep epoxy off the finish. Neatly cut tape away from the small hole openings so excess epoxy can be squeezed to the outside.
Tape the front of the frame to maintain clearance and keep epoxy out of frame. Don't forget, we need clearance at ALL points, including the front of the frame
Apply epoxy to both the pillars and to the insides of the counterbores.
Squeeze the forend onto the barrel until it is pulled down all the way.
The 7-10 layers of tape wrapped around the barrel are the stopping point.
Once the forend is pulled down all the way onto the forend, wrap tape around the forend and barrel to hold it while the epoxy "kicks".
Watch the epoxy closely for first indications it is starting to kick There is a brief period where the epoxy loses its adhesive, sticky qualities and is easily cut like soft clay.
As soon as it is no longer liquid, JUST starting to firm up, cut/pick/scrape ALL the epoxy from the small holes from the outside.
Scratch the tape off the screw heads so you can access the screws with screw driver or allen wrench as the case may be. Remember, once the epoxy is cured, you have to be able to remove the screws.
Step 6 AFTER the epoxy has cured.
Remove tape holding forend to barrel.
Remove screws from forend. If you did not remove the epoxy while it was soft, you will have a problem getting to the screws to remove them.
Remove forend from barrel. Pillars STAY IN THE FOREND.
Remove all tape from barrel, frame, and forend. You should only have a small trace of epoxy to skive away from around the pillars.
Step 7. End Result
Pillars epoxied INTO the forend permanently project up into the forend channel about .020" or more, and there is NO forend contact at ANY point on the barrel or the frame, including both the sides and front of the frame. Relieve the tapered part of the barrel channel where the barrel makes its first step down in front of the barrel lug.
This is the area marked in red X's. The barrel is now as fully floated as it can be with the forend attached to it, and the small contact points around the screws affect the least amount of influence to the barrel as it heats, moves, and vibrates while shooting.
Some details are not pictured, but the above shows the basic concepts and steps to the process to get the end result of a floated barrel. At this point we do not sell pillars or the counterbores. Counterbores are available from most all machine shop and wood working supply houses such as Grizzley.
David White, for one, will make pillars for you as well as do the complete bedding job. His phone is (918) 244-6284.
I personally do not do any wood work for others. The above factory forend is one I did for my own use and for demonstrating the concepts behind the system.
The above information is copyrighted by Dennis M. "Mike" Bellm for individual use only and may not be copied or distributed, either for free or sold.