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Stack Angle?

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08 October 2002, 12:12
McCray
Stack Angle?
Much is made of a rifle having the proper stack angle to insure proper feeding. Just what is the proper angle for the Mauser or a Mod. 70?

It would seem that the angle (in degrees) would be the same for the different families of cartridges, but the magazine width would need to be wider or longer to retain capacity.

If this is too tiresome or complex to handle here, point me towards the reference or tell me where to go. [Wink]

Much obliged, Joe.
08 October 2002, 13:32
Mauser98
Here's a link to another forum that may answer your question

http://www.huntamerica.com/wwwthreads/showflat.php?Cat=&Board=UBB13&Number=139984&Forum=All_Forums&Words=Mauser98&Match=Username&Searchpage=2&Limit=25&Old=allposts&Main=137066&Sear

[ 10-08-2002, 09:24: Message edited by: Mauser98 ]
08 October 2002, 15:25
John Ricks
Stack angle is 30 degrees, does not make any difference what size (diameter) the cartridge is. So, with a little measurement of existing boxes and measurement of a stack of cartridges, one may see that nearly every box in a modern production rifle is too narrow. This is one of the major reasons why the large diameter cartridges don't feed very well!!!! Widen that box!!!

Where does the 30 degrees come from? Simple geometry: Draw a vertical line on a sheet of paper, this line should be parallel to the left side of the sheet of paper. Now draw three equal diameter circles on the sheet of paper, with the circles touching each other and the centers of two of the circles on the vertical line and the third circle centered to the right and tangent to the first two. This is a graphic representation of the cartridge stack in the box. Now draw a line from the center of the top left circle and extend it through the center of the circle on the right side of the "stack". Vola', this line is at a 30 degree angle to the horizontal

Take three of your favorite cartridges, and rubber band then together as they would be in a magazine. Measure across this stack of three with a dial or digital caliper, one jaw touching two cases and the other jaw touching one case. Now compare to the magazine box width in your rifle. Be sure to measure the stack at the same corresponding place in the magazine., i.e., measure over the rims and compare to the rear of the box, measure over the shoulders and compare at the shoulder location in the box, etc.

The 30 degree stack angle gives a balance of the horizontal forces trying to spread the cases apart and the vertical forces trying to make the top cartridge hop out of the magazine. Squeeze the cases together with a steeper stack angle and the cartridges tend to jump up. Spread the cartridges apart with a smaller stack angle and the cartridges are reluctant to rise up and feed properly.

Paul Mauser determined this concept a long time ago.
08 October 2002, 16:54
McCray
John, thanks for the info and the explanation.

Mauser, I couldn't get the link or address to work, but I'll go to HA and do a search (or twelve) and see what more I can learn.

Thanks again, Joe.
08 October 2002, 17:59
Vibe
See if this site helps

http://www.club.guns.ru/eng/konovalov2.html
08 October 2002, 18:25
Mauser98
JMac

Check my previous post again. I think I got it.