Tuned barrel

For general announcements, and anything which does not fit into one of the categories below.

Moderator: Mod

Message
Author
ErrolW
Posts: 29
Joined: Fri Oct 26, 2018 8:30 pm

Re: Tuned barrel

#16 Postby ErrolW » Fri Jun 12, 2020 11:15 am

Yes I understand that as I shoot ftr with a lite weight timber stock with no flex. Like I said lite weight timber with the same structural integrity as cedar. So y do some bench rest shooter build stocks out of balsa wood? I can stand on my stocks with out flexi them and I'm over 100kgs. F open stock with parallel barrel 500grm tuner and still 1kg under weight controlling torque issue. So I must be doing something wrong

Gyro
Posts: 764
Joined: Sat Jun 10, 2017 2:44 pm
Location: New Zealand

Re: Tuned barrel

#17 Postby Gyro » Fri Jun 12, 2020 12:41 pm

Nice. Spruce is another timber with a relatively hi E value. E being the "modulus of elasticity" which is a property of a material that is its stiffness value. Balsa wood I believe for its weight has a VERY hi E value. The Scoville stock uses balsa and carbon fiber. That stock is a top BR item.

The thing is to just understand this stiffness property and to use it in design, like putting the stiffer material to the objects outer layers away from the " neutral axis" ......

Here's an example : shooter "x" has a certain wooden stock on thier FTR gun. No names. That shooter does ok with up to say the 185 Juggernauts and then thinks I can do better shooting the big boolits and reduce my wind drift. NAH ! They struggle from that day on with inconsistent accuracy, untill they give up. True story.

pjifl
Posts: 883
Joined: Fri Jun 17, 2005 12:15 pm
Location: Innisfail, Far North QLD.

Re: Tuned barrel

#18 Postby pjifl » Fri Jun 12, 2020 3:38 pm

When I mentioned that I had different zeros from each shoulder, I was referring to TR sling shooting a much lighter rifle (an old SMLE way back) than an FO rig. The butt is then of course pulled tightly into the shoulder.

I used to think that certain woods shot better than others and were superior but have changed my mind after seeing just about everything used successfully. I have seen them all shoot very well and suspect most of the difference is in the shooters technique and mind.

Before getting carried away with preferences I would like to point out that a typical max weight 284 FO rig using 180 grain 7mm projectiles and 9 inch twist sees the bullet leave the barrel when the stock has recoiled about 1 mm, and rotated about 3 degrees. Thus 'Free recoil' effectively still happens when the butt is lightly contacting the shoulder as long as it is not pulled really hard to the shoulder. The 1 mm is taken up in the spring of your garment - then the bullet has exited the muzzle.

Rotation of the stock of 3 degrees partially locked in a rear bag or even more restrained by a bipod sees the bullet exit. A lighter FTR rifle, using very heavy bullets, associated with more twist will rotate quite a lot more. This in my opinion is what makes the difference.

What actually happens is that the bottom of the butt acts as a paddle and pushes sideways on the rear bag. A rigidly attached bipod does something similar.

A pistol grip, gripped firmly low down, can be a problem because this makes matters worse and is difficult for the shooter to maintain a constant grip every shot. It is best to make contact lightly with the upper part of the pistol grip only for best accuracy.

Those recoil figures may surprise many. They are quite small - even miniscule. Much smaller than what a bystander thinks he sees when a rifle recoils. It is hard to predict the effect of vibrations etc. but Physics does give a fairly definite answer to the recoil figures. Most of the recoil calculators on the web calculate the force of the recoil - few if any calculate amount of recoil movement. Some approximations have been made calculating the amount of rotation above but all slightly overestimate it. The true figure is probably a bit less.

When we wax lyrical about various 'magical' stocks, we should always be factoring in those recoil figures. Certainly, for comfort and recoil convenience after the bullet has left, many of those elaborate stocks are nice. More so in Practical Shooting - but far less so in F shooting.

Peter Smith.

Gyro
Posts: 764
Joined: Sat Jun 10, 2017 2:44 pm
Location: New Zealand

Re: Tuned barrel

#19 Postby Gyro » Fri Jun 12, 2020 4:49 pm

So stock stiffness has no significance whatsoever Peter ? If that's what your suggesting then that's totally at odds with what a great many of todays commentatorss are stating, myself included. It is now a very widely held 'belief' that an overly flexible stock will cost u consistent accuracy.

pjifl
Posts: 883
Joined: Fri Jun 17, 2005 12:15 pm
Location: Innisfail, Far North QLD.

Re: Tuned barrel

#20 Postby pjifl » Fri Jun 12, 2020 5:05 pm

Widely held beliefs are often wrong. Crowd mentality is the norm these days.

The last two time I competed in the NQRA Queens in Townsville I had more Xs than anyone else.
Both times with what most would consider a quite flexible stock, especially in the forend. Fairly strong at the throat just behind the action but not a particularly strong wood. Certainly no Carbon fibre etc. Look horrible but shoot brilliantly. Of course that proves nothing but worth considering.

ErrolW
Posts: 29
Joined: Fri Oct 26, 2018 8:30 pm

Re: Tuned barrel

#21 Postby ErrolW » Fri Jun 12, 2020 5:22 pm

Half the recoil is related to powder charge and rifle set up. But stock set up can play a big part in it ,body position can also play a part look at how a tr shooter sets him self up

pjifl
Posts: 883
Joined: Fri Jun 17, 2005 12:15 pm
Location: Innisfail, Far North QLD.

Re: Tuned barrel

#22 Postby pjifl » Fri Jun 12, 2020 5:32 pm

My previous recoil calculations take into account the mass of powder. Some approximations but should be fairly close. About 1/4 of the recoil is due to the mass and velocity of powder. But at the moment the bullet exits, almost all of the powder is still in the barrel. The rifle setup has almost no effect on rearwards recoil. Some on rotational recoil. It is afterwards that we see significant differences in rifle movement and are fooled into thinking that it is effecting the bullet.

Yes, I am sure that set up is a big factor - especially as to how the shoot 'flows' seamlessly - and some effect on rotational recoil.
Last edited by pjifl on Fri Jun 12, 2020 5:38 pm, edited 2 times in total.

Gyro
Posts: 764
Joined: Sat Jun 10, 2017 2:44 pm
Location: New Zealand

Re: Tuned barrel

#23 Postby Gyro » Fri Jun 12, 2020 5:37 pm

Peter just your words about the impact on where u put your hand on the pistol grip tells the whole story about stock stiffness. A flexible stock is highly sensitive to handling changes/errors. Even a complete dog of a stock can shoot well, but it will be far less forgiving of handling variations. That's basic physics isn't it ?

pjifl
Posts: 883
Joined: Fri Jun 17, 2005 12:15 pm
Location: Innisfail, Far North QLD.

Re: Tuned barrel

#24 Postby pjifl » Fri Jun 12, 2020 5:43 pm

Peter just your words about the impact on where u put your hand on the pistol grip tells the whole story about stock stiffness. A flexible stock is highly sensitive to handling changes/errors.

I do not see that at all. In fact it may be the reverse. The lower hand grip forces the stock to kick sideways at the bore line and any inconsistency is magnified by the lower grip.

Gyro
Posts: 764
Joined: Sat Jun 10, 2017 2:44 pm
Location: New Zealand

Re: Tuned barrel

#25 Postby Gyro » Fri Jun 12, 2020 5:57 pm

Maybe it's like this : a stiff stock will tolerate more handling variations in terms of it staying in a more inert state than a flexible stock i.e. the flexible one more easily gets loaded with stored energy. No problems there, until u release the shot, then the more inert platform/stock will behave a lot more consistently ?

pjifl
Posts: 883
Joined: Fri Jun 17, 2005 12:15 pm
Location: Innisfail, Far North QLD.

Re: Tuned barrel

#26 Postby pjifl » Fri Jun 12, 2020 6:06 pm

Maybe it's like this : a stiff stock will tolerate more handling variations in terms of it staying in a more inert state than a flexible stock i.e. the flexible one more easily gets loaded with stored energy. No problems there, until u release the shot. The more inert platform/stock will behave a lot more consistently ?

Again, I cannot see why.

BTW, I appreciate a beautifully made and finished wooden stock and understand why people love them. I was once like that.

But Consider how the Firearms suppliers stay in business by pushing the latest theories - even fads - just as Suppliers to fishermen make a lot of money from the latest lures !

Gyro
Posts: 764
Joined: Sat Jun 10, 2017 2:44 pm
Location: New Zealand

Re: Tuned barrel

#27 Postby Gyro » Fri Jun 12, 2020 7:02 pm

I chuckled when I fairly recently watched Kelly McMillan ( who probably knows a bit about rifle stocks ) on a utoob vid say ... " Alex Wheeler is the only shooter in the world who believes a more flexible stock is better". He was alluding to a particular theory Alex Wheeler had been espousing, but Mr Mcmillan was getting a point across re what is these days very widely held thinking among stock makers and shooters, who of course could all be wrong. Lord knows we can all see things differently !

pjifl
Posts: 883
Joined: Fri Jun 17, 2005 12:15 pm
Location: Innisfail, Far North QLD.

Re: Tuned barrel

#28 Postby pjifl » Fri Jun 12, 2020 7:10 pm

Yes - we could all be wrong. In fact it is highly likely. Also, a lot of stuff gets reinvented.

My main reason for writing was to get across to people the amount of recoil movement before bullet exit - especially the rotational movement - which is very rarely covered. Both Linear and Rotationally, it is about 50 % larger in FTR than FO for max weight rifles.

Gyro
Posts: 764
Joined: Sat Jun 10, 2017 2:44 pm
Location: New Zealand

Re: Tuned barrel

#29 Postby Gyro » Fri Jun 12, 2020 7:32 pm

Yes Peter it's interesting stuff. I reckon more tests could be done by using 'tracking devices', like Scatt maybe, to learn more i.e. to hopefully properly and accurately observe and measure how the rifle moves IN TOTAL during recoil, before the boolit exits. I believe this would give a lot more validity ( or otherwise ) to the varuous theories about group divergence. IT AINT ONLY THE BARREL THAT'S MOVING.

wsftr
Posts: 202
Joined: Tue Jan 30, 2018 12:58 pm

Re: Tuned barrel

#30 Postby wsftr » Fri Jun 12, 2020 7:44 pm

Its a weird world - I have a flexible stock (or do I - so how do you quantify and measure flexible - the thing we all reckon is bad) - my scores and x counts at regionals and nats suggest its not a problem and that just maybe its the whole package.


Return to “General Forum”

Who is online

Users browsing this forum: No registered users and 28 guests