Elongating underlug pin holes

[Lee Cain]

I've never heard of this until a post on this forum the other day. Is this a standard practice? If so, how much?

 

[Vaino]

After the hole is drilled, I elongate by a 1/32" on each side. I use a small cutter in the Dremel to do this and the critical side of the resulting slot is that away from the barrel which pulls the stock and barrel together. Also the actual barrel lug should be given the same clearance for and aft.....Fred

 

[nuttbush]

elongating the slot for heat expansion. Like Flehto said make the hole longer horizontally but do not widen the slot any or your barrel fit will suffer.

 

[Zonie]

There are two reasons for elongating the holes.
As was mentioned, heat is one reason.
Lets say you build your gun in a 70 degree F room and drill the forward pin hole without clearance.

Now, your gun is sitting on a bench in the sun and the barrel temperature has risen to 140 degrees F. If the breech of the barrel is held in place with a tight tang screw, the barrel will expand towards the muzzle. At that temperature, if the pin is 40 inches from the breech, the hole will move forward .027 relative to the wood.
The barrel would shrink by the same .027 if the gun was carried around in 0 degree F weather.

The other reason for elongating the holes is humidity. I don't have any growth/shrinkage factors for this but wood is greatly affected by high/low humidity and moves a great deal.
I have heard of wooden stocks growing enough to actaully bend the barrel pins so they couldn't be removed. In other cases, they just split out the wood on the forstock.

 

[LRB]

I looked at a smoothie last Jan. that was not slotted, and the entire nose section had separated and come off. Gun was only a few years old. Unslotted lugs will definately affect point of aim also.

 

[Lee Cain]

Thanks alot guys...I'm convinced. My holes are now elongated. :rotf: