Home Forums Hunting & Shooting Hunting Rifles Dimensional Stability Myth

Reading Chuck Hawks article got me to thinking. He maintains that the rifle industry went to synthetic stocks for two reasons, 1) good walnut is getting more expensive, 2) plastic extruded stocks cost the manufacturer about 5 to 10 dollars.

I always thought that rantings against synthetic stocks was just old timers cussing progress. Now I think Chuck Hawks is totally correct. (with the exception of some of the more expensive stocks, all hail McMillian)

Most of these midrange synthetics have aluminum full length bedding rails. I am wondering how dimensionally stable they are under temperature swings. A boat builder who welded aluminum told me how difficult it is to weld a clean aluminum seam because of the creep when the aluminum changes temperature. I wonder if this puts strain on a synthetic when it is taken from a warm hunting cabin into very cold outdoor weather.

Secondly, take for instance the standard 700ADL wooden stock, it is stiff enough for using a sling and it seems to me that if sealed up, especially under the recoil pad, but-plate, and barrel channel that an almost hermetic seal can be accomplished. Then humidity changing the point of impact can be minimized if not almost eliminated altogether.

I agree that the migration away from wood, and to injection molded plastic, has everything to do with economics. And a cheap plastic handle is at least a step down from most any wood handle.

MM

Dixie
You make some good points, better than Chuck's actually... good walnut has always been relatively expensive, but like most natural resources, tastes dictate a lot of what happens and walnut is not an exception. In real terms walnut has been getting cheaper for the last 8-10 years... the reverse is what truly happened, plastic stocks got cheaper, a lot cheaper... <img src="/ubbthreads/images/graemlins/frown.gif" alt="" />

That is not to say that the best walnut has not gotten much more expensive, just straight-grained walnut that dries and machines easily.

Temperature does introduce another potential accuracy problem into the equation, but no worse than wood.

As for sealing the wood, the finishes used by the manufacturers are nothing special as water sealers. Trying to get a thin enough layer under a butt pad to seal and sit nice and tight against the stock is tough business. Dings and cracks in the finsih coupled with pores built into the finish by the evaporating solvents leaves them pretty susceptible to sucking up water.
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Sitka;
That is real interesting about the price of Walnut.

I'm just fishing here mostly, seems like firewood dries out slow from the cut end. And before pressure treated wood carpenters used to paint the ends of dimensional lumber to minimize moisture absorbtion, (ain't I right on that?)

I got a friend who finishes wood floors. Some of these new polyurathane finishes are nearly as hard as diamonds, (if I believe what he tells me)

maybe the laminate woods are the best inexpensive option.

Have you had any eyewitness experience with the wood laminates delaminating in the wet and sea coast conditions up there in Alaska?

Dixie,

Most wood is coated on the end grain to slow down the drying process. This causes the wood to cure more slowly and stay more stable, check and crack less, and warp less.

With the aluminum bedding blocks, it really isn't a fair comparison to welding aluminum boats, just because of the length of the material being used. All materials have a coefficient of expansion/contraction and measured over the length of something as long as a boat, it can be significant. However, a bedding block in a rifle that only measures about 4-5" long, the amount of actual movement will be small enough to be insignificant.
The types of materials used makes all the difference in how the stock reacts to conditions. The mainstream factory synthetic stocks are for the most part injection molded plastics with synthetic polymers added for toughness. Without the added materials, they would be way too stiff and brittle to use for stock material.
The very best stocks, McMillan, Borden, etc... are laid up individually with better materials such as hand laid fiberglass, kevlar fibers, and other exotic materials. On top of using expensive materials, the amount of hand work involved in each stock drives the costs substantially.

I believe, as Sitka does, that with proper finishing techniques a wood stock can be made to be as stable as most anything short of maybe a McMillan- and it will look good doing it. But it ain't easy.- Sheister

dixie
You are rambling here! A few points of correction; the new polyuretanes (Diamondthane for example <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />) are the hardest finishes currently made. They are tough as can be and extremely clear, but they are orders of magnitude softer than diamond. They are only mediocre as true water sealers. If they were impervious the floors would buckle like crazy due to water getting into only one side. Most of the hardest polyurethanes are water-based. Where the water leaves from it leaves a hole it can return by...

As SHeister points out the wood is end-painted to slow the drying at the ends, so the whole board will stress less from uneven drying. Though in some parts of the country the wood is sometimes end-painted to reduce water transport... wicking. That is to keep the water content low enough to prevent rot.

Firewood, any wood dries far faster through the cut end... imagine a bundle of microscopic straws held together with glue and full of water when the tree is cut. As they stand some trees are 2/3 free water. When the wood gets down to about 25-30% water cut (when compared to the weight of the wood after oven-drying) the water held in the cells of the wood starts to leave and the wood then starts to shrink.

Of course the wood does not all dry at the same rate, hence the need to slow down the ends. The biggest problem is that when wood reaches about 6% MC it takes a set and will maintain that size through incredible stresses. If the outside takea a set before the inside it stays larger than it should be and the inside of the wood then shrinks and often causes serious cracking inside the piece, invisible to the outside.

Laminates SUCK! They is ugly as a mud fence, heavy as can be, lousy to checker, expensive and did I mention ugly? Of course that is just my opinion <img src="/ubbthreads/images/graemlins/wink.gif" alt="" /> <img src="/ubbthreads/images/graemlins/blush.gif" alt="" /> I have not seen one delaminating though. My wood stocks of a number of species including several flavors of walnut, myrtle, maples and a few others do just fine when properly finished with a base coat of two-part epoxy and a top coat of oil finish.
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Personally I like laminated stocks. I have had too many problems with one piece walnut stocks warping, the finish peeling, etc. when I hunt in truely wet conditions. Most of my rifles have laminated stocks except the ones for extreme conditions. My last moose hunt saw me in a canoe for five days with the rifle proped up next to me ready for the next moose which might jump into view. Needless to say the rifle was stainless with a synthetic stock and was soaking wet all day every day ( but dried and oiled every night. ) This kind of abuse destroys wood stocks regardless of the finish they get. The .338 in question wore an injection-molded stock in the canoe, but wears a laminated one for all other hunting. I've never had a problem with laminated stocks. I think they look kinda cool.....but then I like harlequin ducks too. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

nimrod
I routinely subject wood stocks to Kodiak weather for far more than a few days or even weeks at a time. My stocks have been swamped in raft bottoms, soaked in rain and salt spray and the only one that has ever warped was one I bedded into a new stock at the last minute and did not seal in the barrel channel after free-floating... hardly the fault of the wood or the finish...

I said laminated stocks are ugly for a very simple reason... they ARE!!! <img src="/ubbthreads/images/graemlins/wink.gif" alt="" /> Comparing harlequins and laminates is just plain low... those little ducks neither need nor deserve that type of abuse. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

My father built a target rifle stock for my older brother of laminated walnut about 35 years ago and back then I lusted after it... I have gotten over that craving! <img src="/ubbthreads/images/graemlins/blush.gif" alt="" />
best to you
art

sd:

i used to build and fly free flight flight model planes. competition was fierce. i got pretty good at it it. what does that have to do with this thread? well, when you are running 60 percent nitromethane model engine fuel in your balsa framed airplanes, youse gots to protect the plane from the fuel. that stuff could get into balsa so fast and seriously weaken it even faster if the wood was not sealed. i used two-part hobby poxy brand sealer. then applied a layer of silk or fiber-glas or nylon or even japanese tissue, depending on which part of the frame/fuselage (the firewall and area just behind got the fiber-glas for strength; you need that with 1/2 A engines running 20,000-plus rpms). then applied another coat or two of hobby poxy. this kind of sealer is what i intend to finish my boyd's walnut stock with for my model 96 based swede. what are some other name brands you could recommend, there, sd? i guess hobby poxy still makes there stuff.
thanks for the reminder on finishes. valuable thread, this.

Fish
Makes me wonder why the balsa after you go through all the gyrations of fuel-proofing it... Must be getting into the realm of other materials' capabilities???

I have used quite a few different brands, but stick to the slowest setting formulas only. Industrial Formulators out of Canada makes G-1, G-2 and Cold Cure and I have used each of them a number of times. Any of them are very good. The G-2 is a 48 hour setting glue that I use when I have a fore end tip of an oily rosewood, many of which give epoxy fits.

I have also used some West System epoxies and honestly have not found any real differences. The quick-setting epoxies lack strength when cured, tend to have less UV resistance and worst of all they lack open time. The curing starts before you are finished applying the stuff and very little gets sucked into the wood...

There are a number of epoxies designed to impregnate rotting log cabin sill logs and most of these are water based and not acceptable for stock work...
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The temps reached in welding aluminum are far greater than any temp change a gunstock is going to encounter. In welding you are going above the temp of plasticising of aluminum. That would definitely cause some dimensional change. The 150 degrees maximum temp change a gunstock would go through would be not be anything close to causing any noticable dimensional change in an aluminum bedding block.
Properly dried and oriented, laminate stocks are pretty stable. They are heavier than Walnut alone, but are less likely to change. I think some look good and some look horrible. It's a matter of taste.
Walnut properly dried, finished and maintained can be very stable. It's the dried, finished and maintained that causes the problems. Factory stocks don't get the attention to detail they probably should, because we aren't willing to pay for it, so they leave a little to be desired in the durability category.
I've always liked the look of blue and Walnut. It is what I grew up with and nothing looks so good. I like stainless and lanminated too, but not as well. I like to take factory stocks and seal all the inside surfaces and they seem to hold up pretty well.
I had an HS Precision stock that had an aluminum bedding block in it and when I sent the rifle to Shilen for rebarrelling, he called and told me the bedding block was uneven and that is needed a couple of passes to strighten it out. I was later told that the aluminum blocks used in rifle stocks are extruded "V" blocks and used as extruded, they are not that straight. I don't know if that's true or not, but I've heard of several having to be machined to get them straight. So, I wonder how many are stright from the factory, and how much that affects people's attitudes toward aluminum in a rifle stock.

Odd,extruded aluminum is often used as straight-edges.

The coating of wood with epoxy allows the use of a wood that would normally get rejected as too soft.I used it on a showy english walnut stock that could be marked with my finger nail.

downwind
Epoxy is the best way to get away with using much western maple... Even makes checkering it possible at whatever lpi you like...
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bchannell
Just walked by the thermostat and thought about how stable metal is and how 150F range would not change it much... then thought again of the thermostat guts and that little bi-metalic strip... <img src="/ubbthreads/images/graemlins/wink.gif" alt="" /> you can do the same thing with two different woods to measure relative humidity... <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />
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You're talking two completely different metals. Those bi-metal strips in the thermostat are not made of the same metal. Thermostats use metal of low heat stability properties, such as chromel, and constanton. They are also of very, very low mass. Respectfully, that cannot be compared to the aluminum alloys used in bedding blocks that have somewhere near 50 times the mass of a completely different alloy.
I'm certainly no expert, and I don't mean to be discourteous, but surely those aluminum bedding blocks are at least made of faily stable aluminum at normal atmospheric temperatures. They are purportedly not machines or cast very straight, I sure hope they're at least of the correct alloy for the intended use.

This is a real interesting thread...

I know plumbers have a chart (I think I have seen it somewhere) telling the expansion of pipe based upon temp change. I figured the aluminum in a wonder stock would creep a little, but if it is fully imbedded in "stuff" seems that just a little creep would cause tension. Just thinking out loud here. And I was thinking no so much about the heat from firing the rifle but the change of temp due to in and out of the house, cabin, etc, and of course the change of seasons. It is not inconcieveable to think a rifle would face an 80 degree sudden temperature change in the winter even as far south as Virginia.

But if the engineering chart says 80 degree change don't make it change much I believe... Any engineers out there that can put their finger on one of those charts... I ain't no engineer and have never even seen one on TV!!! heh heh

Sitka Deer; Real interesting posts, I don't know the first thing about wood in any form and your posts are real informative.

What is the next best thing to high quality walnut?

Dixie
"What is the next best thing to high quality walnut?"

Well that would be second quality walnut, by most accounts... cut down by loggers <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />! There are several different characteristics making walnut special stock wood. The few woods that really compete are some maples, myrtle, mesquite, sycamore, beech and some birches. Beech, birch and most maples flunk out on looks so get used for cheap stocks.

Sycamore flunks out on stability issues and looks, so it gets used on cheaper stocks yet. Mesquite is hard to get in big enough pieces to be commercially viable in large scale operations, which is a shame because it is the single most stable US wood suitable for gunstocks, though it is heavy for most applications.

Myrtle is gorgeous, relatively lightweight, stable in service once dried properly (the rub with myrtle) and the camphor-like smell in the shop when working myrtle is impossible to beat.

Maples cover the entire spectrum of stock uses from plain and soft to hard, heavy and gorgeous; from firewood to exhibition grade gunstocks. Eastern maples (sugar and rock) are good for heavy stocks and can be highly figured and western maple is soft, but often wildly-figured and very serviceable for very lightweight stocks that can be incredibly beautiful. The rest of the maples are utility-grade stock blanks on average, lacking character, stability and looks.

Realize that "walnut" is not a very specific term when refering to gunstocks. There are many native N.A. walnuts and the imports. Black walnut is the common plain stock wood on commercial guns, but better examples do get into the high-grade world. Claro walnut is a native Kalifornia tree and produces beautiful wood with lots of figure and color, often pink, but does not have the depth and strength needed for many applications so is not as highly regarded as the best walnuts.

English, French, circassian and several other trade names are all the same tree and it was imported to the US. The wood can be soft and drab to incredible based on the growing conditions and age of the tree, as well its genetics. Any of these can get into the incredibly expensive range. When the circassian is grown in Turkey and gets to be ancient the wood is beyond description with luster and depth that must be seen to be understood. It costs plenty...

Then there is bastogne or paradox walnuut, a mule of claro and one of the english walnuts. The wood can be as hard as the best Turkish and highly-figured, but heavy and pricey.

There are a number of other walnuts such as nogal and butternut that I have never heard of being used for stocks, but there probably has been one...

Did not intend to ramble quite so much here, likely more info than you wanted. <img src="/ubbthreads/images/graemlins/blush.gif" alt="" />
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sitka - i gotta agree with this opinion! the one exception that i have found is the company known as acra-bond. i am pretty impressed with their stuff (or, at least, how it looks!) have you got any opinions on acra-bond?

tas
Ain't nothin' wrong with the looks of an acra-bond that a mile can't cure <img src="/ubbthreads/images/graemlins/wink.gif" alt="" /> Actually they look ok at a little distance, but up close I cannot like them. Obviously not everybody agrees with me...

Those lamination lines are serious give-aways on keeping your fields flat and true so far a trainer stock to build they might be a good idea.
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downwind
"Epoxy is the best way to get away with using much western maple... Even makes checkering it possible at whatever lpi you like..."
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Mr. Sitka Deer/ Art

What brand of epoxy again????
Where to buy? Same stuff for barrell channel as but plate end as general finish???