Dagnappit!

[Nordnecker]

I decided to bring my current build to show to a friend who collects long rifles. It's about 80% done and I wasn't worried about a little nick or scratch as I still have to finish shape and sand everywhere. I put the gun in the front of my van resting on the floor and leaning against the seat, not worried about a thing.
When I got home that afternoon, I was unloading the van and putting things away in my shop. Huh?, What's this? Something feels warm. I never gave it a thought. The heater had been blowing right on the butt of the gun the whole way, 45 minutes or so.
 I have poor grain orientation through the toe and the heat caused the stock to crack. No, it didn't crack in two, but it probably will after I mortice out the cavity for the patch box.
So, I will be dealing with this. Be Careful.

[EC121]

Get some super thin CA glue from a hobby shop.  It will flow in the grain and stop the crack.  I use it on model airplanes.  It will flow into the tiniest cracks.  The downside is that it doesn't take stain.

[Nate McKenzie]

Also glue a dowel down through the stick past the crack. Start it under the heel of the butt. It will never show and re-enforce the but.

[Acer Saccharum]

The buttplate would not shrink, but the stock will. If the stock shrank from the heat, a lot of strain would occur at the bottom screw. 

Once the humidity in the stock normalizes, the crack will close up. Get some glue in it while it's open and clamp it. Take the buttplate off before you clamp.

[BOB HILL]

You may want to soak this area with some stain before glueing. Alcohol based leather stain has worked for me. It soaks in as deep as the C A glue and drys quickly.It can also be thinned with alcohol to lighten if need be. I usually use N A on my work and have never had a problem blending in flaws or repairs using this method.Much easier than trying to cover a white spot that will not take any stain because of the glue alone.     Bob

[Hank*in*WV]

You may want to soak this area with some stain before glueing. Alcohol based leather stain has worked for me. It soaks in as deep as the C A glue and drys quickly.It can also be thinned with alcohol to lighten if need be. I usually use N A on my work and have never had a problem blending in flaws or repairs using this method.Much easier than trying to cover a white spot that will not take any stain because of the glue alone.     Bob

I've done the same as Bob a number of times. It works quite well. The stain doesn,t even have to be the same color you are going to finish with. Just has to be darker than white.

[Nordnecker]

Thanks everyone but I ended up taking much more drastic action. The grain through the toe was so bad I had about 4 different cracks to deal with. The screw hole in the lower butt plate was not drilled to suit me so that made 5 issues.
Acer- it cracked at this screw also.
I cut the entire lower part of the stock off, about 1/2 way up the butt plate, through the cheekpiece moulding, all the way through the rear extension of the trigger guard.
I'll have to refit the BP, re-inlet the toe plate and a little of the trigger guard and shape the whole thing but it'll be a learning experience.
I cut a new piece of wood from the same stock with better grain. The joint will be under the patchbox on one side and through the cheekpiece moulding and under the TG on the other. Glued it with thickened epoxy.
It'll be interesting to see how many people notice it.
It's walnut and I am not staining. I'll find out more tomorrow.