I am going to have a rifle built in the near future and I am undecided about bedding. I have bought a McMillan custom drop in stock for my Winchester model 70 action. I realize no stock can truly be prefit to be a true perfect drop in for all the minor variations in actions, so I plan on bedding the action in some fashion.
Is there an advantage of pillar over glass bedding? Does anyone do both? [img]images/icons/confused.gif[/img]
Yes, most people do both. I am a student at the Colorado School of Trades for gunsmithing and about 99% of the rifles built/worked on here get both.
Here's how I understand it- from past experience and from the school:
Pillar bedding basically allows you to torque your action screws to a determined load and they make sure it stays consistent. Wood, laminates and most synthetic stocks will crush under too much torque. They also expand and shrink due tohumidity changes and temperature changes. The McMillan is the only synthetic that I know of that the action screws will break before the stock shows any "crush." What the proper torque is for best accuracy with pillars is a start for another discussion. But the point is the pillars allow you to maintain a consistent torque on your action screws.
Glass bedding, using Marine Tex (probably the best), Devcon or an Acraglass product (gel or regular) makes up for the "imperfections" of the stock makers inletting. They have to inlet to fit all actions which can have a wide range of tolerances. Glass bedding gives you a perfect 1 to 1 fit for YOUR action into YOUR stock. This accomplishes a couple of things- it helps to stiffen the receiver and the joint between the receiver and the barrel (most people also bed the first inch or two of the barrel) and second it allows the action to "settle" back into the exact same spot after each shot. In wood stocks it strengthens the wood and helps to seal it against the elements.
There are more advantages to bedding I'm sure but this is the base idea for doing it.
Hope that helps.
PS I build my pillars out of drill rod, not aluminum.
Good job Chris. I have found that barreled actions frequently move in composite stocks after some shooting, unless they are properly bedded in Marine Tex or whatever.
Have a M-70 that isn't bedded yet and I have been shooting it. Had to relieve the bolt handle cut-out as the action is moving back - was OK when I dropped it in. Action is simply finding its place in the stock and maybe the recoil lug is not making proper contact. Bedding will fix that, complete with pillars of course.
You're right Ian, if the recoil lug is not making 100% contact with it's corresponding surface in the stock stuff moves around everywhere! I have a factory Howa in .223 and improved it's groups just by glassing the recoil lug area. Would have glassed the whole thing, but it's a factory "plastic" stock and the epoxy doesn't stick real well. I'll get it restocked one of these days.
Have also seen an action move so much that the bolt handle blew out a big chunk of a FIBERGLASS stock! Good thing you caught the problem and got it fixed!
Thanks Chris. So not one or the other, but both. Makes sense. To achieve a high consistant torque, do most people trade out the normal slot head screws with torx head screws?
Thanks for the info as well Ian. I originally planned on shooting the existing barreled action in the new McMillan stock just to see if the acurracy changed. Now on second thought, I might just have the bedding done at the same time the action is being rebarreled.
Good idea to get it all done at once, you won't regret it.
As far as screws go, it's kinda a preference thing. I have used slotted heads, allen and torques heads. I prefer the last two. Regular slotted screws seem to bugger up even with proper screwdrivers from Brownells, but they will take the torque as good as the other two if not better than the allen head screws. Try what you have and remember normal torque runs about 40 to 60 INCH lbs, NOT FOOT lbs, for pillar bedded actions.
Let us know how it shoots....