Why exactly are wood stocks different than Carbon, chassis, etc.

[longrangelead]

Why exactly are wood stocks so "dead" feeling in recoil compared to carbon, aluminum, fiberglass and all the other man made stuff we've tried?

My hypothesis is the resonant frequency of wood is extremely low compared to the other materials.
Carbon and aluminum are dense and stiff, that's why we use them. I believe this is exactly why they have a higher resonant frequency that we feel during recoil, that "tuning fork" feel of a chassis for example.

I believe the much lower resonant frequency of wood has a damping effect on the steel part of the rifle, like touching a tuning fork to another object.
The wood absorbs the resonance of the metal.

I believe the opposite is true of carbon/aluminum for example. Carbon and aluminum seem to have resonant frequencies much closer to the barrel/action and do little or nothing to damp the resonance and we feel that in the stock or chassis.

From what I can find on googles, wood has a general resonance of 1.1 kHz. I'm sure that varies by species and density within a given species.
I can't find any solid resonance info on carbon fiber/aluminum/steel. The specific products we use in the gun industry may have specific resonance factors that have to be calculated anyway.

This could be a black hole of a rabbit trail. There are quite a few articles on sound absorption/reflection and musical qualities of wood...


I may have descriptive terms wrong but I think the idea is clear.

if some of you big brain engineers can fill this out with more technical information that would be cool to somewhat quantify the "why" behind the "feel".

@Tommyhaak

 

[Marbles]

Resonance is effected by length, is is why altering the length of 1 prong on a tunning form maks it no longer work correctly. Or, on 3 prong flash hiders making the prongs slightly different lengths fixes the tunning fork tone through electronic ear pro.

An interesting look an wood types effect on dampening in electric guitars. https://pmc.ncbi.nlm.nih.gov/articles/PMC8465587/

It sounds like solid carbon fiber guitar bodies are pretty similar to wood, but hollow not so much. Perhaps some of it has to do with having a shell and fill vs sold material more than a true difference in the material. If you hollowed out a wood stock and filled it with foam, I wonder how that would feel?

 

[longrangelead]

there is definitely a lot to it when you get down in the nitty gritty of specific shapes and combinations of materials.

Resonance is effected by length, is is why altering the length of 1 prong on a tunning form maks it no longer work correctly. Or, on 3 prong flash hiders making the prongs slightly different lengths fixes the tunning fork tone through electronic ear pro.

An interesting look an wood types effect on dampening in electric guitars. https://pmc.ncbi.nlm.nih.gov/articles/PMC8465587/

It sounds like solid carbon fiber guitar bodies are pretty similar to wood, but hollow not so much. Perhaps some of it has to do with having a shell and fill vs sold material more than a true difference in the material. If you hollowed out a wood stock and filled it with foam, I wonder how that would feel?

 

[BigNate]

There's a lot to consider here. The density is of course key. I wonder if there's a compressability factor, as wood is individual cells, arranged in linear fibers.

One thing I believe I've actually felt is certain synthetic stocks actually transfer less recoil, while the gun itself wasn't shooting as well. These were "identical" m24's, same ammo, same optics, both in synthetic stocks, one seemed to transfer more recoil but shot better groups.

 

[RockAndSage]

Great post. Something that came to mind would be to check if there's a difference between single-piece solid wood stocks, vs wood slabs laminated together, vs epoxy-filled laminate. I suspect @BigNate's point about compressibility is in play in how that frequency or the actual shockwave is transferred through the cells of the wood.

 

[longrangelead]

There's a lot to consider here. The density is of course key. I wonder if there's a compressability factor, as wood is individual cells, arranged in linear fibers.

One thing I believe I've actually felt is certain synthetic stocks actually transfer less recoil, while the gun itself wasn't shooting as well. These were "identical" m24's, same ammo, same optics, both in synthetic stocks, one seemed to transfer more recoil but shot better groups.

I believe compression or deflection is definitely present. A M70 for instance has to have a few thousandths clearance hehind the tang otherwise it chips the wood.
I don't know if it's overall compression, the thinner sides of the mag well deflecting, or both.

barrel resonance (harmonics) and effects of accuracy in individual rifles has been debated forever. there has to be something there in stocks too.