Hollowing out a rib?

[Scota4570]

I am working on a halfstock.  The BBL is 7/8" 40 cal.  It will probably end up 32 or 34 inches.  The rib is the kind that has the ears that nest the bottom flat.  It seems heavy and chunky.  I was thinking of removing as much as I dare with a 1/4" endmill on the underside. 

Would I notice a difference in the balance of the rifle ?  What are the chances the rib will warp?  Save it for something else and get a regular rib? 

[Joey R]

PM David Rase on this forum and ask him about the rib he hollowed out on a Harpers Ferry rifle he built. Made all the difference in the way it handles.

[smylee grouch]

I did just that with a 1/4 inch end mill but tinned the bottom of the rib first with the solder I was going to use to attach the rib with. That way I didn,t fill in the holes with solder when I tinned the rib. Worked good and the gun balanced nicely.

[Dphariss]

I am working on a halfstock.  The BBL is 7/8" 40 cal.  It will probably end up 32 or 34 inches.  The rib is the kind that has the ears that nest the bottom flat.  It seems heavy and chunky.  I was thinking of removing as much as I dare with a 1/4" endmill on the underside. 

Would I notice a difference in the balance of the rifle ?  What are the chances the rib will warp?  Save it for something else and get a regular rib?

Warpage may well be an issue. I made rib for an English Sporting rifle but i hollowed it in the square. Made a cut to form the flange, then hollowed it, but not as much as I could have, with 3/8" ball mill. Then soldered it to a bar of steel to contour the sides and groove. Trying to profile without a bar of steel to hold it resulted in it warping to the point I had to start over. Photos are in reverse order but you get the idea. You might try soldering a steel rod into the groove of the rib to help stabilize it.

Dan

[Jim Kibler]

Stress in cold rolled (drawn, worked) material can be problematic.  We machine strips of parts at times and you can really see the stress level when one side of the material is removed.  A stress relieving heat treatment will solve the problem.  We use a furnace and hold at around 1100F usually for a coupld of hours (depending on material size) and this eliminates the problem.  You might get rid of most of the stress by just hanging the rib and heating with a tourch to a dull red.  Doesn't necessarily need to be all hot at once.

Jim

[David Rase]

PM David Rase on this forum and ask him about the rib he hollowed out on a Harpers Ferry rifle he built. Made all the difference in the way it handles.

I hollowed that under rib out using a ball end mill in my milling machine.
David

[flehto]

When toolmaking, cold rolled steel was only used on fixtures , etc. and was always used w/o taking the "bark" off.....the warpage was always the result if it was taken off and some warpages were so bad that it was useless. Hot rolled steel is much more stable when removing the "bark" and doesn't warp when it's  machined.. .....Fred

[RAT]

FYI...
Muzzleloader Builders Supply has hollow ribs for sale.

[Scota4570]

Nice to see the hollow ones are back.  That makes me think of turning the barrel 1/2 round and tapering the front half.  I could leave it the full 36" and get good balance.  IT would also look really nice with the wedding band transition.  1/2 round is seldom seen and attractive to me, I like being different.