Science project for Long rifles

[Col. Batguano]

Guys,
We all know that it's a good idea to elongate the holes in your barrel tabs to allow for seasonal stock movement. This morning (-25F) my outdoor humidity was 55%, and indoor humidity was at 3%. That's going to outgas a lot of moisture out of the stock. So, as carefully as I can, I'm measuring length and breadth of all my LR stocks and putting the measurements in the PB's so they don't get lost. Come the end of August, and a full summer's worth of humidity, I'm going to measure everything again to see if there are any changes. Since plain sawn maple tends to move about 1/4" per 12" of width. , and qyuarter-sawn about 1/8", I think the results may be interesting.

 

[BrownBear]

...I think the results may be interesting.

No kidding! Looking forward to your results.

 

[Col. Batguano]

Wood doesn't move lengthwise to any degree, so any movement will likely be from the waviness in the curl, and oblique angles the grain direction forms in it's wave making. I think I'll do the measurements monthly, because outgassing / ingassing is a progressive thing that takes time to happen, particularly with finish on the stock to slow things down. Besides, when it's that cold out (we're supposed to hit -30F tonight) a guy's got to think of something to do to keep their brain from freezing.

 

[Melnic]

I'll be interested to see the results.

Wow, 3% inside, you need a humidifier bad! That's gonna generate static which may not appear to harm electronics, but they get micro fractures and then fail later when it temperature cycles. Dry air is not always good for the lungs either.
My main house has a humidifier and it runs double overtime in the winter just to keep it at 30%. My gun room is above the garage so it stays 55-60F until I work in the room and turn up the heat pump. Weeks like now, I have a portable Humidifier for that room to try to keep the humidity above 20%

Some people who are desperate hang wet towels in the bathroom, don't run the bathroom vent during showers, leave bowls of water around the rooms etc

 

[BrownBear]

Some people who are desperate hang wet towels in the bathroom, don't run the bathroom vent during showers, leave bowls of water around the rooms etc

In the days of wood heat we always kept a big tea kettle on top of the stove. Worked great because we always had hot water, a great luxury when there are no pipes coming into or out of the house. These days we fixed that, but we still keep a big old tea kettle on top of our oil heater.

 

[Rifleman1776]

I doubt you will get any measurable results. However, with humidity that low any wood items in your house could show cracks with the grain.

 

[1950DAVE]

Wood moisture content does not change very quickly . There are calculators online to determine within a reasonable amount of accuracy the dimensional changes of dimensions based on initial moisture content of most all woods. Tangential and radial changes are the most important, longitudinal changes are inconsequential .
Dave

 

[zimmerstutzen]

Green wood may contract a lot. after drying, it may still expend and contract but only in width, rarely ever in length. As said above, perhaps with the transverse grain and curl. It is a good idea to widen the holes in pin tennons, but not because the wood lengthens and shortens as much as both the wood and the metal move ever so slightly due to temps and humidity. Sometimes together, sometimes in opposite directions. There are woods that contract very little from green to dry, such a Palownia, but Palownia also twists and warps more. So while it rarely checks as it dries, if turned green, into a bowl, by the time the bowl dries, it may be pretty lop sided from the twisting.

 

[zimmerstutzen]

Part of your science experiment was already completed for about 200 different wood species at https://www.wood-database.com/wood-finder/

and here.https://www.wood-database.com/wood-articles/dimensional-shrinkage/

Longitudinal shrinkage is rarely more than .02 % that is indeed insignificant. OTH shrinkage across the grain and through the grain can be substantial.

 

[necchi]

We all know that it's a good idea to elongate the holes in your barrel tabs to allow for seasonal stock movement

We do? What about non-seasonal, or any season "heat" change of the metal? Like a cold barrel (no matter the season) changing during a 50 round match?
All finished wood is challenged during the dry periods of winter for those of us that suffer it. That's when I treat my wood stocks with a drink. Pick your poison, doesn't matter really, as long as there is something to care for the wood.
(Do your other fine furniture too while your at it)
Wood and metal are different, allowing for the change that can happen with both at any time (or seasonally) is a lesson we've gleaned from our ancestors.

 

[Loyalist Dave]

So..., Do we think it a wives' tail, OR are we awaiting more data?

Would there be a difference if it's not from atmospheric humidity levels, but from actually being carried in the woods for several days when it rains, and thus the stock of the rifle was exposed to much more moisture than merely from humidity in the air?

LD

 

[1950DAVE]

So..., Do we think it a wives' tail, OR are we awaiting more data

Or is this "Much about nothing"?
Dave