Yet another DIY bedding question

[ntsqd]

I assumed so, but no experience, so no idea.

 

[jarnold37]

The amount of total surface area "grabbing" the action is the key. Pardon the analagy but when constructing a building one does not pour the footers and put "props" on corners to take all of the support. The load needs to be supported equally over entire area. The bottom metal is flimsy as well. Dont think that the aluminum block needs support by the bottim metal. Think how much surface area that block has gripping on its entire surface. Same even with no block. Look at all of the surface area of the entire action if being totally gripped equally by the bedding. I have seen the bluing worn off of the area where the pillar had contacted the action. Only a very small amount of support by the diameter of the pillars minus the hole in pillar to support most of the stress. With clearance around screw, it will move on those pillars. Yes, as mentioned before, the bedding only shrinks one quintrillionth of a whatever, it does shrink - leaving the support or grip of entire barreled action on almost no surface area, only the perimeter area of two pillars. With no pillars, the screws pull the entire surface area of the action into contact which gives much more support. If the screws can move inside the pillar, and the recoil lug has any flex at all there is movement. Basic physics. Think about it.

 

[25WSM]

That's why almost every custom rifle is Piller bedded. Because they shoot worse. So all us custom builders are doing it wrong by using pillers. The reason you see where the pillers sit on the action is it's metal on metal. That will show up. The bedding is smooth and doesn't leave marks on the receiver. With out pillers your stock will compress and you can't keep a proper torque on the screws. Call any custom builder and ask if they Piller bed. Call McMillan and Manners and ask if you should use pillers. The answer is yes. Sure you can bed without pillers but why do half the job.
Shep

 

[ntsqd]

The flaw in your logic is that the stock is not made of soil. While compressible, it is not that compressible. Go back to your Strengths of Materials text and review point loads versus distributed loads. Can have both, sometimes at the same time. Some particular materials may not embrace one or the other, but both are viable loadings in metals.

The purpose of the bottom metal, as with regard to the action screws, is to act as a washer of sorts. To be an area larger than the OD of the pillar so that it can not easily be pulled thru the stock. Even single shot target actions use what amounts to being a large washer under the screw head. We call it an "escutcheon", but it is just a fancy washer.

If the action is moving on the pillars either someone didn't torque the action screws, someone did a bad bedding job, or the stock is so flexible that it wasn't worth the effort and should have been tossed.

 

[Mram10us]

Here's where the old BR argument starts with regard to metal on metal with pillars, or small layer of bedding between pillars and action.

 

[25WSM]

I have no problem. More glue less screw.
Shep

 

[ntsqd]

I could make an argument in either favor, but I lean towards more metal less bedding because the metal is less compressible than the bedding. That's splitting hairs though, neither is terribly compressible.

 

[cohunt]

Unfortunately lots of modern rifles have plastic "bottom metal", trigger guards, and escutcheons (on blind mag rifles). Plastic compresses a bit and or cracks or breaks. I try to replace all bottom plastic with aluminum or steel but it's not always possible.

 

[25WSM]

When does it make sense to make bottom metal out of plastic. Only when the bean counters say to do it. Plastic just doesn't belong on a rifle. When ships were made of wood and men made out of steel rifles were made from both. None of that is true now.
Shep