MBR & the like - Why are they so?

John Kielly

John Kielly

Shari's fan club
I'm a recent convert to 1000 yard benchrest here in Australia. Usually, I'm happier on my belly, shooting F/TR & 1200 yard match rifle, but there's more than a bit of overlap....

When you look at the average 1-200 yard rig, the stock is low at the forend tip & has a fair bit of slope where it rides the back bag too, presumably to clear the shooter under (free) recoil and to minimise torquing. When I look at all those cute 1000 yard stocks, they're all Tooleyesque in appearance. The forend tip is action deep (& sometimes more), there's a big vertical pistol grip that wouldn't go astray on the average Palma rifle & they track flat at both ends. The only obvious design element is the belly of the butt is deeper than the pistol grip so that the latter doesn't interfere with the bag during nosebleed recoil.

Right now, I'm in the making & using a straight prone stock with a 3" plate attached for the rest & a slide bogged onto the butt while I'm shooting F class, and, man does she twist during recoil! I have to reposition it every shot. She sits high, but no more than a MBR does - some of the guys have them on my home range. So, comes the question:

Is an MBR or clone stock going to do any better for me off my belly or off the bench at 1000 yards? What arcane magic is built into that stock that defies conventional wisdom for short tange benching that will make it a sweet shooter with heavy recoiling calibres?
 
The 100-200-300 varmint class rifles have specific rules that require a certain amount of taper in the stock to preclude having a "return to battery" situation. This is all spelled out in the NBRSA/IBS rulebook.There are checking devices available to determine if the taper meets the letter of the law rulewise. The MBR stocks generally do not comply with these taper rules although they could be used on a short-range Unlimited/Heavy Bench bag gun. I see them quite a bit used on ARA rimfire rifles that are shot from (1) piece rests and do not have taper or weight rules to comply with.

Mike Swartz
 
John

Take a look at this.

[edit] Overview
The moment of inertia of an object about a given axis describes how difficult it is to change its angular motion about that axis. For example, consider two discs (A and B) of the same mass. Disc A has a larger radius than disc B. Assuming that there is uniform thickness and mass distribution, it requires more effort to accelerate disc A (change its angular velocity) because its mass is distributed further from its axis of rotation: mass that is further out from that axis must, for a given angular velocity, move more quickly than mass closer in. In this case, disc A has a larger moment of inertia than disc B.


Divers minimizing their moments of inertia in order to increase their rates of rotation.The moment of inertia of an object can change if its shape changes. A figure skater who begins a spin with arms outstretched provides a striking example. By pulling in her arms, she reduces her moment of inertia, causing her to spin faster (by the conservation of angular momentum).

The moment of inertia has two forms, a scalar form I (used when the axis of rotation is known) and a more general tensor form that does not require knowing the axis of rotation. The scalar moment of inertia I (often called simply the "moment of inertia") allows a succinct analysis of many simple problems in rotational dynamics, such as objects rolling down inclines and the behavior of pulleys. For instance, while a block of any shape will slide frictionlessly down a decline at the same rate, rolling objects may descend at different rates, depending on their moments of inertia. A hoop will descend more slowly than a solid disk of equal diameter because more of its mass is located far from the axis of rotation, and thus needs to move faster if the hoop rolls at the same angular velocity. However, for (more complicated) problems in which the axis of rotation can change, the scalar treatment is inadequate, and the tensor treatment must be used (although shortcuts are possible in special situations). Examples requiring such a treatment include gyroscopes, tops, and even satellites, all objects whose alignment can change.

The moment of inertia can also be called the mass moment of inertia (especially by mechanical engineers) to avoid confusion with the second moment of area, which is sometimes called the moment of inertia (especially by structural engineers) and denoted by the same symbol I. The easiest way to differentiate these quantities is through their units. In addition, the moment of inertia should not be confused with the polar moment of inertia, which is a measure of an object's ability to resist torsion (twisting).

Dave
 
new stock design

John
I have a new stock design that has the barreled action off set from the centerline of the stock, to handle the torque even better than the MBR.

Dave
 
Dave,

Thanks for your comprehensive & prompt responses. I suspected asking that question on this forum was about like shooting fish (a Tooleyfish maybe) in a barrel, but I thought I might trawl a couple of testimonials at the same time.

best wishes
 
John

As far as testimonals go, it's the most copied long range stock out there. My/our new design takes it to the next level of torque control.

Dave
 
Dave Tooley said:
John
I have a new stock design that has the barreled action off set from the centerline of the stock, to handle the torque even better than the MBR.

Dave
Click to expand...

Bruce Bear Custom Rifles has had an offset stock for over a year, to handle the torque situation.
Gary.
 
dubya --

wonder where he got that idea from?

You should look into the history of the offset stocks and see where it originated from.... bet you may find Dave's name close by it.......

Donovan Moran
 
Dave Tooley and John

Dave was that english? I asked the same question before and Charles E gave me a very similar answer and I didn't get his explanation either.

John its a rudder.If you have a sailboat it will tip over when the wind hits the sail so you add a huge rudder.On a torquing rifle you add a Tooley buttstock.
See that was much easier.
Lynn
 
Lynn said:
John its a rudder.If you have a sailboat it will tip over when the wind hits the sail so you add a huge rudder.On a torquing rifle you add a Tooley buttstock.
See that was much easier.
Lynn
Click to expand...
Yup, but it's like Chinese. As soon as you finish you want more!. :D
 
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