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PostPosted: Tue Jun 27, 2017 9:37 pm 
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I would like to have an explanation as to why barrel block rifles are not more dominant. I think they would do away with stressing of the action by the long barrel dangling out front supported by the action alone. Also it would seem that the block would reduce the absolute magnitude of barrel displacement during the barrel oscillation during the bullet's ride down the barrel and exit because there would be less barrel length in front of the block. The block would be a node in the vibrating barrel. Carrying this line of thinking further, one might argue that the block should be placed at the muzzle and reduce muzzle displacement even more. Any data which bears on this issue will be appreciated. Thanks, Jim Storm jamesestormmd@yahoo.com


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PostPosted: Wed Jun 28, 2017 1:51 am 
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Location: Taunton, Somerset
Quite possibly because conventional bedding techniques, a well supported receiver and free-floated barrel, work. Past barrel bedding, such as the old Freeland Pressure bedders, and the more recent Unique X-Concept and EC Universal stock's with rubber-dampened clamps, show that conventional bedding isn't the only way to achieve excellent scores. However as the majority of smallbore rifles have conventional bedding, and shoot well enough for the vast majority of shoooters there is no impetus to change. Many shooters don't bother to torque test their bedding, so are unlikely to want to experiment with the position of barrel blocks.

I'm not sure how a block at the muzzle would work in practise. I'd think a stock that long will require a lot of extra weight at the button to balance the muzzle.


Last edited by Tim S on Wed Jun 28, 2017 6:07 am, edited 1 time in total.

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PostPosted: Wed Jun 28, 2017 5:16 am 
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To achieve positive compensation there needs to be consistent vertical barrel vibration. I have not run the tests, but others have reported that overly thick barrels or ones clamped to eliminate muzzle vibration do not perform well.


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PostPosted: Wed Jun 28, 2017 5:28 am 
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http://www.geoffrey-kolbe.com/articles/ ... barrel.htm


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PostPosted: Wed Jun 28, 2017 5:48 am 
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Mike Ross had a different result from a small test; nothing conclusive but interesting.

http://forums.delphiforums.com/n/main.a ... 2068947686


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PostPosted: Wed Jun 28, 2017 4:10 pm 
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Joined: Mon Mar 22, 2004 6:03 pm
Posts: 258
Location: ...ain't in Texas no more....
James Storm wrote:
I would like to have an explanation as to why barrel block rifles are not more dominant. I think they would do away with stressing of the action by the long barrel dangling out front supported by the action alone. Also it would seem that the block would reduce the absolute magnitude of barrel displacement during the barrel oscillation during the bullet's ride down the barrel and exit because there would be less barrel length in front of the block. The block would be a node in the vibrating barrel. Carrying this line of thinking further, one might argue that the block should be placed at the muzzle and reduce muzzle displacement even more. Any data which bears on this issue will be appreciated. Thanks, Jim Storm jamesestormmd@yahoo.com


Clamping the barrel now introduces several other factors versus conventional bedding:
-There are now (2) two vibrating masses with one on either side of the block: the action and the barrel. This can make the system more complex.

-What is the interface between the barrel block and the actual barrel? Metal to metal or some type of elastomer. If it is metal to metal, it must be very accurate so it does not create point contacts out of plane. If an elastomer, what durometer and amount of crush to allow a reasonable level of vibration vs the amount of damping it will provide.

-Barrel blocks shift the overall mass of the system and in effect, due to location, shift the frequency of the barrel due to the shorter length cantilevered in front of the bock. This may - or may not - create tuning issues and/or make it more difficult to tune.

-Just because there is a clamp does not guarantee that it is a node. The initiation of the vibration is in the chamber, which will not be inside of the bedding block area. Don't have the FEA programs to view this, but this is my engi-nerd gut feeling on this one.

Just some random thoughts.
ken


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PostPosted: Wed Jun 28, 2017 7:59 pm 
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I am grateful for all your replies. I could not get delphiforums to tell me what the conditions were that I must agree to, so I could not open that reference. In summary, so far, the vibration issue appears very complicated even to engineers who specialize in the subject. The business of stress on the action and concomitant complications of tuning the bedding screws, etc. remains a plausible advantage, as does putting the block at the muzzle and letting the rest of the rig float. I lack the training to analyze the vibration issue so experiment appears the most viable avenue of investigation. Have any of you experimented on rifles using light beams and rotating mirrors as we did in high school physics? I remember hearing maybe 50 years ago about the complicated analysis of the vibration problems in the 4 turboprop engined Lockheed Electra commercial airliner which were difficult to resolve and caused it to fail and crash. I think the solution involved moving the engines slightly and that cured the problem, not unlike the small amount of barrel tuner change which can dramatically change group size. Thanks again for your help. Jim


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PostPosted: Wed Jun 28, 2017 8:49 pm 
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Joined: Sat Nov 15, 2008 4:20 pm
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Location: Scottsdale AZ
Going back quite a way to when I shot bench rest rifle. we considered the way to accuracy was to have short stiff barrels. A block holding that barrel just in front of the (free floating) action was one of the "hot ideas" of the day, but stiff, sleeved actions were also popular.


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PostPosted: Thu Jun 29, 2017 7:52 am 
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Joined: Wed May 26, 2004 9:49 am
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I've owned and use a "barrel block" set up for shooting, the Mike Ross stock, and currently a Jeff Madison designed and built stock. The Madison stock is actually built with a tuning setup that is simple but works. The tuning is accomplished by dampening the vibrations of the action. It is repeatable, consistent and allows for small precise adjustments. Jeff doesn't build this stock anymore which is too bad, it is a testament to his skills. I'm surprised actually that someone hasn't produced a clone, although a French company has a stock that allows you to either mount with action screws or use a barrel mount, Espirit Carabine. It's gaining a pretty good reputation, with most using the barrel mount. I not certain how many stocks Jeff built, so they don't come up for sale very often, but they are a work of art that performs beautifully.


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PostPosted: Fri Jun 30, 2017 1:35 pm 
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The article cited by patriot was particularly humbling for me. It requires a great deal more study. Others have investigated this business for over a century and with a great deal more physics knowledge and experimental sophistication than I have. Still it does not answer for me the question of barrel block use or disuse. As one of my humorist friends observed once: "This is what becomes of teaching a boy to read." Jim


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PostPosted: Fri Jun 30, 2017 2:30 pm 
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Location: Scottsdale AZ
Flip a coin.


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PostPosted: Sat Jul 01, 2017 2:39 pm 
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"This is what becomes of teaching a boy to read."

Add a curious open mind with a healthy scientific skepticism and forming the correct questions becomes nearly as important as discovering the answers.

Remember that Einstein succeeded by making the problem simple, something he learned from Galileo. Formal knowledge often over complicates the perspective or instills biases.

Enjoy the journey.


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PostPosted: Sat Jul 01, 2017 6:46 pm 
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I find that it is hard to accept new ideas and to do things differently than they have always been done. We follow the crowd. We recoil from change, laugh and deride the new and those who do things differently, and then when the new seems to work better, we tend to accept it without examining it coolly. If Joe wins a match with a new rifle, most tend to assume that the win is due to the rifle and don't consider that the win could be due to luck, skill, ammunition, or something else. Barrel blocks look different and I have often wondered if this is the reason for their lack of wider use. Action bedded rifles derive from military and field arms where weight, cost, ease of production, etc. are the design goals, not extreme accuracy. We should keep this in mind when searching for ultimate accuracy.


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PostPosted: Sun Jul 02, 2017 2:51 am 
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Location: Taunton, Somerset
Wasn't the free floating of barrels a civilian development? Traditionally military rifles were stocked to the muzzle, and often pressure bedded. Ordnance factories and civilian contractors did not bother with compound bedding actions; that was a time-consuming job.

For many shooters a lack of financial resources, time, and technical/gunsmithing skills mean they have to buy the best rifle they can. Designing or building their own is out of the question. Nor do dealers offer to loan rifles on test for seveal months. So we look around to see what is winning before parting with our cash. Yes, there are many other factors to success than the rifle, but it's a start.


Last edited by Tim S on Mon Jul 03, 2017 6:25 am, edited 1 time in total.

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PostPosted: Sun Jul 02, 2017 11:53 pm 
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James Storm wrote:
I find that it is hard to accept new ideas and to do things differently than they have always been done. We follow the crowd. We recoil from change, laugh and deride the new and those who do things differently, and then when the new seems to work better, we tend to accept it without examining it cooly.


I think this is.true, as demonstrated by the exclusive use of the bolt style action in general for position and prone shooting. To my mind, the falling block action would be superior, something along the lines of the walther block action from many years ago.


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PostPosted: Mon Jul 03, 2017 1:18 am 
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mbradley wrote:
I think this is.true, as demonstrated by the exclusive use of the bolt style action in general for position and prone shooting. To my mind, the falling block action would be superior, something along the lines of the walther block action from many years ago.


That's a little unfair. As the Walter BV rifles were produced in very small quantities, the last falling-block to be readily available was the BSA Martini International. While BSA made a fine barrel, the design was really prone-only, and even then was lagging behind Continental rifles in the ergonomics. If you wanted a Free Rifle the choice between a bolt-action Anschutz/Walther et all or a BSA was a no-brainer.

Remember the Maennel? It used the rotary breech of the 19th C Austrian Werndl service rifle. While the breech was super-short, issues with quality control hurt sales.


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PostPosted: Mon Jul 03, 2017 8:40 am 
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Joined: Fri Jan 18, 2013 11:59 pm
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Some of us still enjoy shooting 100+ year old Marlin Ballard, Stevens 44 1/2, and Winchester 1885 designs; old school quality.

Attachment:
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MarlinBallardModel6_1.jpg [ 80.7 KiB | Viewed 315 times ]


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