Pillars then bedding, methods?

[Judd]

As a student of Al's internet school of bedding rifles, his method works really well, and those nylon bushings make things really simple!

100%

I’m an Al disciple as it pertains to bedding, it works!

 

[AlNyhus]

Here's something to think about:

If we assume that even the best bedding compounds may exhibit some shrinkage, why would we want the action to rest on two different materials...the natural material of the pillars and the bedding compound cradling the action (everywhere but over the pillars)?

 

[gunsandgunsmithing]

Shrinkage with devcon or marine tex is so minimal that we really shouldn't even call it that. I know it's like .0004 per cubic centimeter with devcon. That's about 10x thinner than a human hair(depending on age and..which hairs). And who's bedding a centimeter thick? Realistically, say maybe close to 1/4th of that. I don't have to do the math, hopefully. Put it like this...it's still TIGHT if done right. It's just less tight. That ain't much "shrinkage.", albeit factually true..it shrinks some. Keep in mind...a 1.0000 peg wil NOT fit into a 1.0000 hole. They are the SAME, as in, no difference, hence no fit.

 

[gunsandgunsmithing]

Here's something to think about:

If we assume that even the best bedding compounds may exhibit some shrinkage, why would we want the action to rest on two different materials...the natural material of the pillars and the bedding compound cradling the action (everywhere but over the pillars)?

I'd honestly say that thermal expansion of aluminum pillars is of more significance and ya gotta keep in mind, the other materials expand and contract too, just not exactly at the same rates. Splitting a mighty fine hair here when the wind is really gonna decide things on match day.

 

[AlNyhus]

Shrinkage with devcon or marine tex is so minimal that we really shouldn't even call it that. I know it's like .0004 per cubic centimeter with devcon.

Agreed, Mike. The entire 'bedding shrinkage' is something that with modern compounds isn't really an issue. In the rare cases that bedding does exhibit some movement, the likely cause is the stock material itself shifting around and moving the bedding compound with it. I fixed just such an issue last season for a local BR shooter...the material under the bedding had shifted. A good pal just had the same thing happen to his LV rig, only it was a glue in.

If people don't think a quality composite stock can move, just stick one in the trunk of your car on a hot day and check it later on.

 

[gunsandgunsmithing]

Agreed, Mike. The entire 'bedding shrinkage' is something that with modern compounds isn't really an issue. In the rare cases that bedding does exhibit some movement, the likely cause is the stock material itself shifting around and moving the bedding compound with it. I fixed just such an issue last season for a local BR shooter...the material under the bedding had shifted. A good pal just had the same thing happen to his LV rig, only it was a glue in.

If people don't think a quality composite stock can move, just stick one in the trunk of your car on a hot day and check it later on.

Yessir, agreed. Another example is, I'm not sure how many years it actually takes for fiberglass to fully cure but it's more than a few. You can literally take years old fiberglass panels and somewhat mold them in bright sunlight. We tend to think of synthetics as being stable but they are not. At least not for many years in the case of fiberglass and they too change with temps, pretty much in real time, similar to metals but at different small rates. I think this is an example of how every detail matters until it doesn't. That is typically around 9:00 am at most ranges. Lol!

 

[Tucker65]

If people don't think a quality composite stock can move, just stick one in the trunk of your car on a hot day and check it later on.

I've often wondered how much, if any, the stock moves after they are sent off to one of the stock painters and they apply all those layers of paint and clear on them. I would think that with a bunch of coats of that fancy high gloss clear that when it cures it has to be trying to make something move. Maybe the stocks are rigid enough though and it doesn't even affect it enough to be measurable.

 

[gunsandgunsmithing]

I've often wondered how much, if any, the stock moves after they are sent off to one of the stock painters and they apply all those layers of paint and clear on them. I would think that with a bunch of coats of that fancy high gloss clear that when it cures it has to be trying to make something move. Maybe the stocks are rigid enough though and it doesn't even affect it enough to be measurable.

Never checked it but like I said in my previous post, fiberglass will move for many years even without temp changes and will ALWAYS move with temp, just not as much as most metals do. But I would say the very thin paint/clear is of virtually zero or very near it, consequence to the bigger picture. Substrate is usually what counts. But absolutely! Clears and paints shrink! They shrink enough to see it over time. Ever seen a super slick paint job over fiberglass and see it a few years later, and see the fiberglass cloth pattern show up later? Not sure percentage wise how much of that is substrate vs clear but it certainly does happen. It just happens, but easy enough to fix if the painter put enough material down to allow for sanding and buffing. Not typically a problem in our little world. More so in a volume body shop environment where they put as little on as possible. There are reasons for that too, beyond cost of materials though.

 

[Fast14riot]

Composite resins, primarily polyester resins which includes gel coat and laminating resins, is under a state of continuous cure, for the life of the product. One of my race boats is S-glass and polyester, the other carbon fiber and epoxy. The polyester resin and gel coat exhibits cracks at the corners because of continued shrinkage. The epoxy boat does not. This is not to say that epoxy does not shrink, its just at a different rate.

Regarding heat and flexibility, most all resins (epoxy, polyester, vinylesters) will soften if exposed to time at temps above the cured temp. This is why autoclave parts are so exceptionally good, cured at high temps not likely to be seen in natural circumstances, and maintains designed shape with very low CTE. I have a very nice, custom made rudder that is worthless because it set in a hot container for weeks, horizontally and has over 1/2" of bow now. It's still just as strong, stiff and everything, just a different shape.

Bedding over the tops of pillars for me is about having a monostructural contact between action and screws. If bedding shrinks or moves, I can tighten actions screws to predetermined torque and expect a certain amount of strain applied to the bedding. Not just pushing the pillars into the action harder because the they're already contacting.

 

[pertnear]

I've had good luck accurizing my rifles with pillars & epoxy bedding. I have to add, that all are wood stocks & hunting rifles. Here is my humble understanding of what the process is suppose to achieve. The stock material, especially wood, can slightly change due to environment conditions. Also materials can expand or contract with the tightness of the action screws. Metal pillars minimize this problem. Bedding the action to the stock creates a solid & uniform "handle" for the barrel to consistently oscillate against during bullet passage. A free floating barrel helps also in allowing the barrel vibration freedom. It must be admitted though, that a barrel channel pressure point can sometimes dramatically improve accuracy. But this also introduces another possible problem to adjust & monitor.

Obviously we are discussing bolt actions here. For rifles with 2 piece stocks, I wish someone could come up with some universal rules of wisdom (or magic?) to making them always behave!

 

[Dimner]

I have never even heard of bedding on top of the pillars! To me that makes no sense at all! The pillar bedding should have already set the vertical limit in relationship to bottom metal and magazine feeding.

The glass bedding is about setting all other diemensions for and aft and right and left if the action has already been pillar bedded in advance.

If the stock has not already been pillar beded then the glass bedding all relationships can be set by the bedding compound alone.

Seldom do I find anything gained especialy on a hunting rifle or varmint rifle by going beyound a simple pillar bedding job.

If a pillar job goes bad in time it is easy and fast to fix! When a full glass bedding job goes bad it is a pain in the rear to fix and takes a lot of time to fix or redo!

Because bedding shrinks. Then all u have are pillar contacts

 

[gunsandgunsmithing]

Because bedding shrinks. Then all u have are pillar contacts

Technically, yes. See my previous posts. True but we just tend to over analyze things like this by nature. The amount of shrinkage of modern epoxies is inconsequential if done right. Put it like this...if done right and the gun isn't shooting, I would look a whole lot of other places before blaming it on .0001 of bedding shrinkage, or likely even less than that.

 

[Dimner]

Technically, yes. See my previous posts. True but we just tend to over analyze things like this by nature. The amount of shrinkage of modern epoxies is inconsequential if done right. Put it like this...if done right and the gun isn't shooting, I would look a whole lot of other places before blaming it on .0001 of bedding shrinkage, or likely even less than that.

To be honest, my comment was a hasty reply before I finished reading the thread....What I really should have replied about bedding over pillars is:

That's what @AlNyhus and many other talented folks told me to do and it just plain works!


I was shocked that a nobody hack like me could bed a rifle with less than 0.002 movement. When I test my Tikka stock one out of 5 times it has 0.001 movement. Other tikka stock has 0.002 movement one out of 5. 0.001 other wise.

My bedding strategy has always been....

..welp, I'll give it a shot, if I muck it up, I'll drive it over to pierce engineering and pay them for their black magic

 

[Bc'z]

I've often wondered how much, if any, the stock moves after they are sent off to one of the stock painters and they apply all those layers of paint and clear on them. I would think that with a bunch of coats of that fancy high gloss clear that when it cures it has to be trying to make something move. Maybe the stocks are rigid enough though and it doesn't even affect it enough to be measurable.

Wood will expand and contract over time from temperature and humidity, the finish will flex and move with it, not restrict it.

 

[hpshooter]

Respectfully, that's a long way around a better approach. I make the pillar I.D. 5/16" and glue a nylon sleeve in the bottom of the pillar that 5/16" O.D. and 1/4" I.D. to center the guide screws in the pillars and provide clearance for the action screws. When the barrelled action comes out of the beddimg, a twist drill pops the sleeves right out of the pillars. A little clean up and off you go. -Al

No disrespect taken, I actually printed out and saved your older post on your method and source of the sleeves you use in my resource file when it was first posted. Even thought about turning some sleeves from some Delrin but figured the thin wall would not be easy to machine.

I only work on my own firearms and tend to use whatever materials I have on hand in the scrap box to make what I need. Tend to over think things and will spend an hour fabricating to save fifty cents.

 

[Alex Wheeler]

Both wood and fiberglass/carbon stocks never stop moving. But I have seen some differences in how they move over time. Fiberglass or carbon can move a lot early on, mostly while curing. Its the epoxy thats moving. This is why any bedding material test that measures shrinkage of a post cured machined block of epoxy is not really a good test. The vast majority of this movement happens while curing. This is how you can get a warped stock that came out of a straight mold. There was more epoxy on one side of the mold and it shrunk more. Once that initial cure is over, you will still see movement with temp. You can set a rifle in the bags with it tracking perfect, after the sun hits one side for a while it will track left and right. But it will return to normal. Wood on the other hand has no rules really. Plywood or gunstock laminate is pretty good about long term stability. But it can still twist. Natural wood is the worst. Or at least it can be. It can be good for years then twist so bad you have to scrap it. Nothing will stop it from moving. You can layer as much carbon fiber as you want in between the layers and it will just tear itself off. Thats one reason I dont care for carbon layers. The most extreme example I can say I have seen is an M1A. I got an old Vietnam era stock that I did all the AMU stuff to and glass bedded it. It shot great. Now this stock is 60 years old? I moved to Mt. and it warped so bad there was at least 1/16" air gap under the action. There was no fixing it. I have also had well aged wood stocks that would not go back into their bedding after coming back from clear. 2 weeks and it shrunk that much. While I still like real wood, and those cases are rare. If you are playing with real wood it can happen even 10 years down the road. I like a good glue in. The wood will tear before that bond to the action will fail if you do it right. If you dont want to prep it right because you want to keep the bottom of the action pretty then dont do it.

 

[Evan]

Both wood and fiberglass/carbon stocks never stop moving. But I have seen some differences in how they move over time. Fiberglass or carbon can move a lot early on, mostly while curing. Its the epoxy thats moving. This is why any bedding material test that measures shrinkage of a post cured machined block of epoxy is not really a good test. The vast majority of this movement happens while curing. This is how you can get a warped stock that came out of a straight mold. There was more epoxy on one side of the mold and it shrunk more. Once that initial cure is over, you will still see movement with temp. You can set a rifle in the bags with it tracking perfect, after the sun hits one side for a while it will track left and right. But it will return to normal. Wood on the other hand has no rules really. Plywood or gunstock laminate is pretty good about long term stability. But it can still twist. Natural wood is the worst. Or at least it can be. It can be good for years then twist so bad you have to scrap it. Nothing will stop it from moving. You can layer as much carbon fiber as you want in between the layers and it will just tear itself off. Thats one reason I dont care for carbon layers. The most extreme example I can say I have seen is an M1A. I got an old Vietnam era stock that I did all the AMU stuff to and glass bedded it. It shot great. Now this stock is 60 years old? I moved to Mt. and it warped so bad there was at least 1/16" air gap under the action. There was no fixing it. I have also had well aged wood stocks that would not go back into their bedding after coming back from clear. 2 weeks and it shrunk that much. While I still like real wood, and those cases are rare. If you are playing with real wood it can happen even 10 years down the road. I like a good glue in. The wood will tear before that bond to the action will fail if you do it right. If you dont want to prep it right because you want to keep the bottom of the action pretty then dont do it.

I didn’t scuff up the bottom of my BRL before devcon gluing it into my laminate stock. I just cleaned it up carefully with acetone and then glued it in. 3 yrs later (a few months ago) I attempted to pop it apart to send to Jim for a check up and to have a PPC extractor fit. I couldn’t get it apart! I set a clothes iron on the picatinny rail, drove a wedge between the forearm and barrel and checked it for movement every 5 minutes or so. After an hour, it finally let loose with a loud bang - taking chunks of the laminate with it.

Got off track there. I used stainless steel pillars, squared on top, bolted to the round action for the initial bedding. Pulled it all apart, cleaned up the action, scored cross hatches into the bedding with a dremel, blew it out with compressed air, and then glued in the action. The stock broke when I tried to disassemble it 3 years later because the bond was so strong.

 

[Alex Wheeler]

I had a big mistake recently. 100% my fault. But I had to take an action out of a stock I had glued in that morning. So we are talking 6 hours in. I took parts of the stock out. Enough it went into the burn pit. No iron I have experience with will get out a good glue in. I heat a rod or action wrench until blue and slide it in the action. It takes 4 cycles at least. I tried the iron thing. I wont live long enough for that to work. I have taken apart a lot of them. Big difference in how they come apart based on prep. Probably why you see a divide between those of us who like a glue in and those who dont. Since your sending it back to Jim. Ask him his opinions. He is the one that gave me advice on how to prep the actions early on. I have found his advice to be very good.

 

[gunsandgunsmithing]

I had a big mistake recently. 100% my fault. But I had to take an action out of a stock I had glued in that morning. So we are talking 6 hours in. I took parts of the stock out. Enough it went into the burn pit. No iron I have experience with will get out a good glue in. I heat a rod or action wrench until blue and slide it in the action. It takes 4 cycles at least. I tried the iron thing. I wont live long enough for that to work. I have taken apart a lot of them. Big difference in how they come apart based on prep. Probably why you see a divide between those of us who like a glue in and those who dont. Since your sending it back to Jim. Ask him his opinions. He is the one that gave me advice on how to prep the actions early on. I have found his advice to be very good.

Yes, the old irons work best and yes, heating a rod speeds everything up nicely too.

 

[skeeljc]

Maybe attach the pillars to the action. Bed the action and pillars to the stock. Then mill .010" off of the top of the pillars and open the holes for bolt clearance.