How much can a stock REALLY move?

[holzwurm]

Buillding a Jaeger in Kentucky next month and have been working on the furniture ahead of time so I can spend my time shaping wood rather than polishing and soldering metal. I've been experimenting with that front sling swivel anchor, I've made 4 so far and am not yet satisfied. This morning this thought dropped nto my questrion basket.

This rifle barrel is solidly anchored to the stock with a tang bolt into the trigger plate (as normal)  AND by an 8-32 screw up through the nose cap and stock into a soldered (or dovetailed) button on the bottom flat about an inch and a half from the muzzle. IOW's. the barrel and stock are in effect imoveably anchored together at both ends

How is this stock going to move? Why would it be necessary to slot the under-lugs if the stock can't expand.

Stock movement has always been one of the mysteries to me since I started doing this. I can understand that the "old & original" gun makers may have had a probelem with movement because they were not working with kiln dried stockwood. That isn't the case with we modern makers. Furthermore, wood expands horizonal with the grain - it doesn't stretch measurabley over a length of three feet.  Why are we still sloting underlugs and how can this next rifel stock moved at all considering how it's solidly anchored at both ends

[Jim Kibler]

Curled wood changes length with the grain more than straight grained wood.  Shorter barrels such as on a Jaeger will result in less stock movement as well.   That's not to say you won't get some movement though.  While the amount of movement might be tolerable on a Jaeger I find it a mystery why this practice was continued on some early longrifles.  RCA # 42 is a perfect example.  The nose cap is screwed directly into the barrel.  This rifle has almost a 46" barrel and the forestock has fairly heavy curl.  Guess it's just a cary over from the Germanic tradition.  As an aside, I was talking with Mark Silver about this subject and he mentioned that even today on German built full stocked centerfire rifles, it is still standard practice to screw the end of the stock to the barrel.

[Stophel]

Wood that is straight in the fore end isn't going to expand and contract (I have read that an oak log or board 20' long will shrink only 1/4" in length from green to 10% moisture).  Any curl or cross grain will change that.  If the wood is real curly, that basically is lots and lots of cross grain stacked up, and it durn sure will lengthen and shorten.

I was working on a gun and got the barrel inlet.  The weather here was unusually nice with low humidity.  When done, I set the barrel aside and began to work on another part of the stock.  In the meantime, our normal, swamplike humidity returned, and a couple of days later,  I tried to put the barrel back in the stock and my pins wouldn't line up!  The wood was protruding past the end of the muzzle about a 16th of an inch, whereas before, it was just a hair short of the muzzle!  This was only moderately curly maple.

I have had straight grain walnut fore ends that don't move at all lengthwise.

[keweenaw]

Wood is more stable in dimensions along the length than across the grain.  What one can get by with depends alot on where the gun will be for it's life and how dry the wood was to start.  Mark Silver mentioned to me that one time he built a long rifle that had the nose cap pretty close to the end of the barrel.  During the summer it grew until about 1/16" of the nose cap was in front of the end of the barrel.  Required doing some resetting.  But maple is less stable than walnut, which in turn is less stable than cherry and as Jim pointed out curly is worse than plain.

Tom

[Mark Elliott]

My experience is that curly maple will move 1/16"-3/32" at the muzzle from Winter to Summer.   

[Captchee]

  Myself I slot my under lugs for 2 reasons
1) wood expansion
2 barrel expansion
 The slot lets the   two move  Independently.

 I to have  had flush nose caps , end up being to far forward  as the wood expanded.
 
 We must also though keep in mind that steel also goes through changes when out in the direct sun and heat of summer  or under heavy continual firing .
 Granted this is extreme  conditions.    But if one finds a barrel that  tends to walk when hot . One has to wonder what  pressure is being applied to the pins . 

[Stophel]

Just make sure you have room fore and aft in your inletting to accommodate the movement of the barrel tenons.   

[B.Habermehl]

I had a really curley stock that would move nearly 1/8" during the humid summer months. I had to elongate the barrel tennon slots longer than I origionally made them as one pin started a crack.  Even though the slots in the barrel tennons were slotted 1/8" wide to start with. This piece of wood really moved around more than I had ever seen before.

[Dave R]

Holzwurm,
I understand what you are thinking and felt there was no reason to slot the underlugs ! I will pass on my experience with a custom made .32  13/16  42"full length flinter I had commissioned a builder to build for me many years ago, I had a few years of fun shooting that little southern! One winter day my Father and I were shooting just outside of town and noticed that the gun was shooting a couple or so inches low, Upon inspection approx half way down the barrel a noticeable bend in the barrel! The underlugs were not slotted and the wood shrunk and bent the barrel! I straightened it in a press and slotted the underlugs and everything was ok!It is hard to believe but it is a true story!
Dave R

[Ron Scott]

Just a couple notes that will flush out the details in this particular instance.  The total barrel length on this project is 24.5 inches.
The stock material is straight grain European Walnut.

[jwh1947]

I can only speak of central PA where the humidity fluctuates from somewhat dry to very humid, regularly.  Our stocks expand and contract all the time, and unless the wood is totally dryrotted it can be expected to move seasonally.  This will affect the forearm the most, for obvious reasons.  If we don't slot our tennons here we have bring-backs with tedious repairs and refinishing.  That's one man's experience.

That is also why we judge a finish based upon how it holds up in inclement weather.  Insides also get sealed and treated for moisture, obviously.  Ours get soaking wet and stay right.