Stock Rigidity

Get or give advice on equipment, reloading and other technical issues.

Moderator: Mod

Message
Author
Tim L
Posts: 281
Joined: Mon May 19, 2014 7:11 pm
Location: Townsville

Re: Stock Rigidity

#31 Postby Tim L » Fri Mar 23, 2018 12:03 am

The "Spear of Destiny" is an obscenely pretentious piece of gimmick marketing offering to sell shooting skill. There's nothing in that stock that isn't in one of Bobs, Oh! Except Australian Rosewood of course. (Although I think this one is Wallnut?)
20170922_163944.jpg

Thanks to Bobs awesome efforts (and no shortage of skill and ingenuity) along with one of Peter Bevans Ultra actions, I get to shoot FTR with 30" of parallel Maddco, making this an all Aussie gun (All be it rests on Sebs gear. :D )

And just to put this post on topic, the stock is just the right stiffgidity.
You do not have the required permissions to view the files attached to this post.

Gyro
Posts: 258
Joined: Sat Jun 10, 2017 2:44 pm
Location: New Zealand

Re: Stock Rigidity

#32 Postby Gyro » Fri Mar 23, 2018 8:11 am

Absolutely Timothy ! You guys are lucky to have someone with Bobs skills !!

I waz gonna do a stock in the timber/carbon laminate style. I just went down a more complicated time consuming path. Your stock and say RodD's stock that Bob built look good to me.

I like my stock too but I'm over thinking it could actually be better than anyone else's like I first thought it could be ! Its just another way.

The likes of Speedy has decided there's a problem with a 'hinge point' in some stock designs so he's designed that out with a particular solution. An expensive solution. I totally agree with his thinking but it takes time to prove if the thinking is flawed or not, or at least has measurable gains.

Working with a laminated wood/carbon system is a good way and is clearly a build method much along the lines of what's already in common use. But what you gain with the inclusion of the carbon - and by using the right fiber layup direction - is the stiffness because carbon fiber as a material has a significantly higher Modulus of Elasticity value than any wood ! Plus you keep the vibration-dampening properties of the wood ?

Actually laminating up the raw shape is perhaps the easiest part ? All the shaping and the inletting would be tricky without the right gear especially if you wanted a really pretty final product that didn't need painting, to hide imperfections. I'm just waffling on here because I build my stuff. Because it's FUN.

Tim L
Posts: 281
Joined: Mon May 19, 2014 7:11 pm
Location: Townsville

Re: Stock Rigidity

#33 Postby Tim L » Fri Mar 23, 2018 2:47 pm

Hopefully Peter Smith will be at the NQRA Queens in May. If he is I will take a picture of his stock. I believe it will undo many myths. It's not that he didn't put thought into it, Peter is very much a thinking mans shooter. He can also do, with some offcuts of ply, what others can't with the best timber the world has to offer.

I think there are many ways to skin this cat. I think we have to make a few assumptions of what we think are the important factors, then take a holistic approach to solving them. I don't think all the answer lie in the stock. I do, however, think the stock needs to 'match' the rest of the gun , and I think that can differ depending on what is being shot and the shooting style. I'd agree with Speedies assessment of hinge point, for me it was the drop comb that most stocks seem to have. I think that if someone is shooting a retail round the recoil effects are somewhat reduced compared to trying to get the most out of a hand load shooting a heavy projectile, which is where F Class seems to sit for any given calibre. The concept behind the design Bob did for me (Charlie Watson has a couple over there btw Giro) was to eliminate the drop comb so all recoil forces come straight back. The light weight of the stock, combined with the Ultra action from Peter Bevan allowed me to put more of the weight in line with the axis instead of under it. Running with the minimal twist and slowest powder that will work (in my humble opinion) also smooths out, if not reduces, torque effect.
When thinking through the design I cast my mind back to the development of protecting people in the passenger compartment of cars. For years it was all about strength and stiffness, and trying to stop the impact forces reaching the passenger compartment. Stiff, ridged structures that were meant to stop the object getting to the passenger. They did that, unfortunately it was the stiff ridged structure that got to the passenger instead. It took time for thought to deflect into not stopping the forces, but rather absorb and divert them to somewhere safe. Now we have crush zones so you can write your car off by hitting something at carpark speed!
I figured there are 3 main effects to deal with. Muzzle lift, torque and harmonics.
For F Class, elevation is the killer so I just figured that doing anything that might reduce muzzle lift had to be a good thing. The drop comb went, the parallel barrel puts max weight at the muzzle and a reduced lead angle came from the "FTR" reamer. (Apparently a steep lead can cause muzzle lift, I think that snippet came from the Aussie target shooter world.)
We are never going to stop torque, but here I felt that if it's going to twist, I want it twisting about the axis of my choice, and I want that as close to the bore as I can get it. I pinched an idea from DG Rod Davis and use the scope to cancel (or mimic) the torsional effect of the stock. The scope is obviously lighter than the stock so it was a case of removing stock material as it gets further from the axis. Material in the butt is pretty redundant anyway, all it does is hold the butt plate.
Harmonics, I believe, are dealt with in the loading room, and it appears with knobs. I don't think I'm quite ready to display my knob in public yet but it's a work in progress for barrels that refuse to sing when naked.
Anyway, I ended up with what you see (as well as some hidden, secret stuff (Bobs intellectual property :?: )).

It's early days but the results look promising.

12267.jpeg


I like to think the incline is purely down to spin drift. :) Time will tell I guess.

It certainly isn't the only way of doing it. Jason Mayers ended up with 3 guns at the WC's and I think they all ended up on the line. He is certainly a guy who can get a gun to shoot.
You do not have the required permissions to view the files attached to this post.

Gyro
Posts: 258
Joined: Sat Jun 10, 2017 2:44 pm
Location: New Zealand

Re: Stock Rigidity

#34 Postby Gyro » Fri Mar 23, 2018 3:58 pm

Mmmmmmmmm very interesting ...... the thing we need to be mindful of too is to be 'agnostic' about much of our ideas ? So much of our theories are provisional at best. As you say Tim of Peter Smiths stock which sounds as if it might fly in the face of the conventional wisdom ?

One thing seems likely to my mind : the shooter needs to do THE SAME thing with the gun handling for every shot. Then even if it was the wrong thing at least the gun would see the same wrongness each shot and would behave the same way ? If you do the maths on how much even a TINY change in the direction the barrel points will open a group ..... hence a tuner or a mass weight perhaps ?

Or just free recoil it with a bloody light trigger so the gun is near totally free to behave as it likes while the bullet gets free of the barrel. At least that approach will be the most likely method to allow the gun to do the SAME THING with each shot ? That's all I can cope with currently !

I've just crossed to F Open after 4 years of FTR. My thinking has evolved to a belief that the winning F Class shooters get away quick shots. Ya don't get on the podium in hard conditions when u have a long-winded highly specific gun handling shot routine ! You might maintain good vertical though. Guess Tim we are both thinking out loud. I love playing with field rifles too but with F Class and string shooting our shooting package gets a very REAL test. It's all bloody interesting stuff.


Return to “Equipment & Technical”

Who is online

Users browsing this forum: Dobbo and 1 guest