Stock Rigidity

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Tim L
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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.
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Gyro
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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
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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.
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Gyro
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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.

Gyro
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Re: Stock Rigidity

#35 Postby Gyro » Tue May 15, 2018 6:58 pm

Sungazer : the E value is an abbreviation for "modulus of elasticity". It is a property of a material and relates to a materials stiffness.

So long as my opponents run what I see as overly flexible stocks I'll be most happy !!! I would expect them to shoot well in the easier conditions when u have time to focus on the "gun handling". I say this because if you handle a flexible stock just a little bit wrong you are toast !

Now I tell u a story sungazer : in 2017 I shot FTR and through our Nationals week I got to learn something. Through the early parts of the week my groups were pretty loose and had vertical. Much too much vertical. I was shooting free-recoil. Anyways that night I reflected over a cold beer and thought I'd try stuffing my rear bag a little to get it tighter/harder. Next day I went back and I thought the groups were better i.e. less vertical. So by the end of the week I had got the rear bag packed as tight as and the groups just got better and better !

So when I got home ( a 7 hour drive ) I took the rifle on its bipod and rear bag out to the shed and put it on the concrete floor of the shed and plonked the rifle in it and by pushing down on the guns rear, in the bag, I could watch the scopes crosshairs climb about 1 MOA. When I tried the same trick with the rifle on another bag the cross hairs barely moved. So I then noticed the bag I had used at the Nationals had a heap of stitching and vinyl/leather under the ears so it was bouncy there.

The moral of the story ? These little things matter a LOT. The maths goes like this : if the front and rear rests are 700mm apart, just .001" relative movement of the rifle in those rests set at that spacing, will move the bullets point of impact 1" at 1000 yards. So just imagine what a bouncy rear rest is gonna do to your group ! And that's just one variable.

Chopper
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Re: Stock Rigidity

#36 Postby Chopper » Tue May 15, 2018 10:08 pm

Interesting :D chop

sungazer
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Re: Stock Rigidity

#37 Postby sungazer » Wed May 16, 2018 8:46 am

Thanks very interesting. Glad I filled the bottom (plastic base that had hollows) with liquid nails added some weight and took out a little spring.

Gyro
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Re: Stock Rigidity

#38 Postby Gyro » Wed May 16, 2018 9:58 am

sungazer wrote:Thanks very interesting. Glad I filled the bottom (plastic base that had hollows) with liquid nails added some weight and took out a little spring.


All good. Now my little story is for a FREE RECOILING gun. The rules I believe change when you "handle " the firearm. In which case I strongly suspect u might actually want some forgiveness/give in the rear rest .......

Jase PTRC
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Re: Stock Rigidity

#39 Postby Jase PTRC » Wed May 16, 2018 1:16 pm

Rebel105 wrote:
Gyro wrote:The problem lads is it sounds like a bad stock is being referenced here. What's wrong with a good carbon fiber stock ? Look at all the winning that's been done with the Bob Scoville stock.

I have no vested interest in carbon. I just know if it's used right it is very stiff. My current stock has 'Hi Modulus ' carbon fiber tube in parts and uni-directional panel in others. The tube I had made by C-tech here and the zero-degree layup panel I got from Dragonplate in the USA. Easy as.

My stock still isn't right I'm sure, so I continue to develop it. I'm sure it's too low at the back for example, which seems to allow it to torque more than is desirable ? Many stock builders have tried many different ideas going back many years. Innovation is fun but it does NOT always work.

Gyro,
I'm not mentioning brand of stock on this forum but I can say it's of composite manufacture, A lot of styrene foam is used in the butt and forend i've since found out to keep the weight down. It has a carbon fibre skin and not much carbon internally only where it's bedded. Had I known of the composite nature before I would not have purchased it.
Geoff


I run a stock of this construction, i have found it to be quite sensitive to touch and took some getting used to as far as how i interacted with it letting off shots. So i do not touch the rifle at all except for the trigger shoe, using a seb bigfoot rear bag i anchor my firing hand on the nose of the bag and free recoil. I have found this to be a very successful method. Im running in F Std and even with a 1kg trigger this worked well. Other people with this same stock have found this to be the optimal way also.

Gyro
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Re: Stock Rigidity

#40 Postby Gyro » Wed May 16, 2018 2:15 pm

Sweet Jase ! So is that off a bipod or a "full-on" big front rest ? And is your F Std trigger weight rule still 1KG ?

The above questions I ask perhaps take this thread down another path but I would take from your post that "a shooter can get away with using an overly flexible stock so long as they only touch the trigger shoe" ?

Jase PTRC
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Re: Stock Rigidity

#41 Postby Jase PTRC » Wed May 16, 2018 2:34 pm

Im using a seb mini and have now gone to the 500 gram trigger as the per the rule change. I wouldnt say this stock was overly flexible but if you were running a heavy parallel barrel it may require some weight added to the butt to balance it out. I have an aluminium tube which is 7/8" diameter in the butt and use slugs of crankshaft heavy metal or mallory metal as its also known (heavier than lead by volume) to bring it up to weight and put more weight over the rear and this greatly improved bag riding/tracking

Gyro
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Re: Stock Rigidity

#42 Postby Gyro » Wed May 16, 2018 3:21 pm

Jase PTRC wrote:Im using a seb mini and have now gone to the 500 gram trigger as the per the rule change. I wouldnt say this stock was overly flexible but if you were running a heavy parallel barrel it may require some weight added to the butt to balance it out. I have an aluminium tube which is 7/8" diameter in the butt and use slugs of crankshaft heavy metal or mallory metal as its also known (heavier than lead by volume) to bring it up to weight and put more weight over the rear and this greatly improved bag riding/tracking


Very cool ! That Mallory Metal I now know is cool too with its very hi density and E value ...... but for your purposes it's just adding weight.

You F Std guys Free Recoiling off rests I guess will keep u always on your own target ! NOT so for the FTR shooter who takes the Free Recoil path !!! I took that path for FTR and used to wear some tricky padding on my shoulder plus I had a tricky butt-plate I made that absorbed recoil so with big bullets I only ended up 3 targets down instead of 5 after firing it haha !

Allowing a 500 gram trigger for u guys would I suspect effectively "open the door" for Free Recoiling in the F Std Class ?

Jase PTRC
Posts: 216
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Location: Adelaide SA "PTRC"

Re: Stock Rigidity

#43 Postby Jase PTRC » Wed May 16, 2018 4:16 pm

I have never had an issue free recoiling, to get back to my original point on carbon stocks i have seen comments from shooters here having trouble getting rifles to shoot which i suspect are the same brand of stock i and one of my club mates use with great success. (My club mate Cameron had a 60.8 at 800 mtrs at the SA queens during the lead up) and we used the same stocks for our f std state teams rifles last year which shot great also. My question is could the issue some people may be having possibly be to do with unfamiliarity with how a particular style of stock likes to be handled? Or could it be that the specific combination of barrel, action etc combined with this stock just didnt gel for some reason? And if the latter is the case why would that be?

Gyro
Posts: 349
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Location: New Zealand

Re: Stock Rigidity

#44 Postby Gyro » Wed May 16, 2018 4:48 pm

I wouldn't have an issue with free recoiling either in F Std Jase, especially with the lighter trigger u guys are now allowed to use ! Funny thing is I reckoned that relatively heavy trigger weight u guys used to have would have at least helped preserve your class as something that was actually related to TR. But surely not now cos free recoil has gotta be the easiest route to the podium ? If it was Bipods only then the advantage goes ?

Anyways, coming back to the stiff Vs flaccid stock topic I reckon it's totally possible to drive a flexible stock to a high level. BUT surely it's accepted by most that a flexible stock is always going to be less tolerant of gun-handling errors ? If so then there's your answer I say.

Wal86
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Re: Stock Rigidity

#45 Postby Wal86 » Wed May 16, 2018 7:36 pm

My only suggestion is if you are going to go down the ridgid stock path, think about the materials that it's made from and the qualities it has in regards to "absorption"....
I can tell you now that those stocks i think your talking about have very poor absorption qualities, which has quite alot to do with the poor/critical handling characteristics...
Stocks like this will also magnify any setup problems within the rifle which will narrow your node window or make it non existent, therefore making it nearly impossible to tune especially at longer ranges...


Just a thought
Cheers


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