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-   -   Mann Accuracy Device (http://forums.thecmp.org/showthread.php?t=6338)

wvminer 01-18-2010 04:27 PM

Mann Accuracy Device
 
Any ideas on mounting a Mann device? I am thinking about buying one and want to be able to use it.

joe wilson 01-20-2010 02:48 PM

A CMP member did a good job on mounting one. He has it for sale in the WTS bolt action section I believe.

VMFn542bob 01-20-2010 04:41 PM

Quote:

Originally Posted by joe wilson (Post 49426)
A CMP member did a good job on mounting one. He has it for sale in the WTS bolt action section I believe.

It has been sold but the buyer and seller and several others who have a MANN Device can be found on this active thread.
http://www.thecmp.org/forums/showthr...highlight=MANN

wvminer 01-21-2010 02:39 PM

I must have had a senior moment. I didn`t look at the whole thread on the Mann build job. I just glanced at the last part when I first saw the info. That is a beautiful rifle and a great job.

rocknrod 01-22-2010 08:28 AM

I read the whole post.
I had to look up what a Mann accuracy device is :)
http://www.odcmp.org/1001/mann_inc.asp

UncleWilly 01-25-2010 02:44 AM

I read the above referenced link and while I found it interesting, it STILL failed to explain just what the heck the Mann devices are and how they were used, other than the obvious, that they are fat barrels screwed into bolt action receivers. Anyone? Anyone? Bueller? Bueller? They are obviously used for some kind of testing, but how about some examples or description please. Thanks. :-)

VMFn542bob 01-25-2010 10:43 AM

Quote:

Originally Posted by UncleWilly (Post 52335)
I read the above referenced link and while I found it interesting, it STILL failed to explain just what the heck the Mann devices are and how they were used, other than the obvious, that they are fat barrels screwed into bolt action receivers. Anyone? Anyone? Bueller? Bueller? They are obviously used for some kind of testing, but how about some examples or description please. Thanks. :-)

Information on the MANN barrel is very scarce but I think a picture is worth a thousand words. Last year I placed a post on the old forum regarding this subject but the link to that post is not currently active.
Here is the text of that post which includes links to a photograph of the MANN device as it was used early on and my observations and conclusions. Take it for what it's worth. I think the MANN barrels currently available from the CMP are a great value but if you want to alter it to look like a sporting rifle it will cost you.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
posted 9 July 2009
VMFn542Bob
Posted - 07/09/2009 : 11:20:38
--------------------------------------------------------------------------------
In my humble opinion -
The mann accuracy barrels were designed to test ammunition only.
The barrel was designed to eliminate all possible influence it might have on the performance of the ammunition.
The 1903-A3 receiver was chosen because of its availability and known reliability.
Early testing was done in the field where the barrel was fitted with two precision steel bearings, or donuts.
One bearing was placed near the breech and the other near the muzzle.
Photos I have seen indicate they were secured to the barrel with a set screw.
The device was then placed up-side-down on a precision steel "V" way block securely attached to a stable platform.
The precision of the bearings and the "V" way allowed the device to be returned to the same firing position after each shot with minimal affect on the direction of aim.
Sights were not needed because the device was testing the repeatability of ammunition, not the devices ability to hit a bull eye.

The devices currently available at the CMP are fitted with a collar near the breech.
It is my professional opinion that this was used to secure the device to a stationary platform, perhaps indoors, allowing the barrel to otherwise float freely.
This would have been an obvious improvement over the method used for testing in the earlier days shown in the photos where the barrel was supported at both ends.
I have already placed an order.
I plan to make a platform to hold the device by the collar in my Hyskore Dangerous Game Machine Rest with provisions for a Picatinny rail above the collar to mount a scope. I will make no modifications that will not allow it to be restored to it's original configuration.
If I live long enough.

Early field testing photo
http://www.nps.gov/spar/historycultu...l_shooting.jpg
Mr. Al Woodsworth, Springfield Armory, testing ammunition from a Mann accuracy barrel supported in an improvised rest made from a machine gun mount. (Caption found in Lt. Col. William Brophy's book "The Springfield 1903 Rifles"
(This comment was added here 2/28/2014)

Closeup of the same photo
http://i623.photobucket.com/albums/t...ing8x10JPE.jpg

The CMP Mann Accuracy Devices by Steven T. Rutledge
http://www.odcmp.org/1001/mann_inc.asp

--------------------------------------------------------------------------------
Edited by - VMFn542Bob on 07/09/2009 11:22:40 ; 02/29/2014

VMFn542bob 01-25-2010 02:40 PM

My MANN Accuracy Device Barrels
 
MANN Accuracy Device barrels & 1903-A3 Springfield
This photo (TOP) shows two Mann Accuracy Device barrels chambered for the 7.62mm NATO (.308) which I received from CMP Sales in 2009.
They have 21.5" stainless steel barrels with a 1 turn in 12 inch right hand twist rate fitted to Remington 1903-A3 receivers.
The barrels and the receivers appear to be new and are in pristine condition. If they have been fired it was only a few times.
They are pictured above a 1903-A3 (30-06) Springfield that I bought for $45 through an advertisement published in the American Rifleman Magazine in early 1970s.
The rifle was assembled with surplus parts, a new GI barrel and a new aftermarket receiver.
I removed the front sight and replaced it with an IDEAL (later Lyman) Olympic sight.
I saved the original sight. I also refinished the stock. It is a real good shooter.
http://i623.photobucket.com/albums/t...1903-A3Spr.jpg

Remington 1903-A3 Receivers on MANN devices
Top view of receivers and closeup of rear sight dovetail - rear sight not included
A commercial scope mount is available that attaches to the rear sight dovetail but it requires modification to the stock and bolt.
http://i623.photobucket.com/albums/t...onMANNdevi.jpg

Outside Dimensions of MANN barrels
View of MANN barrels showing different steps in diameter
Collar overall length (including shoulder) = 2.760 inches
Coller shoulder width - 0.503 inches
Collar minor diameter = 1.5000 inches (very finely finished)
Coller major diameter (shoulder) = 1.757 inches
Barrel diameter (4 sections, from collar to muzzle)
Section 1 = 1.250 inches : Section 2 = 1.232 inches : Section 3 = 1.244 inches : Section 4 = 1.236 inches
These diameters vary approximately +/- 0.003 inches across each section and from one barrel to the other.
The location of the steps on each barrel are within a few thousands of an inch in same place on both barrels.
http://i623.photobucket.com/albums/t...ANNbarrels.jpg

My professional opinion of the purpose for the steps in barrel diameter is a well thought engineering plan to purposely break up the normal resonance of the barrel and elimiate as much inaccuracy as possible created by the barrel. I believe that to remove it for cosmetic purposes would be a mistake.

UncleWilly 01-25-2010 07:08 PM

So I gather from this that SOMEONE in the Army would lock this barrel into a fixed frame and use it to test ammunition? You could measure projectile velocity and group size without having to account for any (or much) barrel vibration. Obviously this wasn't issued at the tactical level but only to higher level arms labs. Any idea who used them? Perhaps those organizations have some kind of unit history that would show them in use.

VMFn542bob 01-25-2010 07:28 PM

Quote:

Originally Posted by UncleWilly (Post 52667)
So I gather from this that SOMEONE in the Army would lock this barrel into a fixed frame and use it to test ammunition? You could measure projectile velocity and group size without having to account for any (or much) barrel vibration. Obviously this wasn't issued at the tactical level but only to higher level arms labs. Any idea who used them? Perhaps those organizations have some kind of unit history that would show them in use.

You and I are of the same mind with your first statement. I haven't a clue how they would have measured velocity back then, when those old MANN barrels in the photo were tested. But the addition of the precision collar that is present at the breech on the current rifles leads me to believe that is where that version MANN rifle was supported, probably on a sled, and that the barrel was as free floating as it could possibly be without floating in space. As previously stated, I can only conjecture about this unique 'rifle'. I feel certain that the Army specified how it was to be made and in all likelyhood the manufacturers of ammunition contracted to the military were required to use it for testing. I have no idea what may be used now because technology runs faster than my mind. No doubt there is plenty of information available on this device under the current 'Freedom of Information' laws for anyone having the financial resources to look for it.


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