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Old July 3, 2007, 12:20 PM   #1
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270 WSM crimp

I am working up some reloads for the 270 WSM and measured the overall length of some Winchester factory loads which came out to be 2.765. When set to this depth the bullets seem loose in the neck of the brass---is this a round which should be crimped. Input on this would be greatly appreciated. The brass was full length resized with a Lee die.
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Old July 3, 2007, 01:39 PM   #2
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If it is loose, either you are using a smaller bullet whose shorter bearing surface doesn't enter the neck adequately, or you are not sizing the neck down far enough, or the neck is too hard and is springing back from resiszing. In the latter case, you will need to anneal the necks.

If you have calipers, you can measure the diameter of the outside of the neck on a loaded new commercial round, and measure it on a resized but not loaded case. The sizing die should make the neck 0.001-0.003" smaller in OD. If it isn't smaller (check all the way around) than the loaded round, either the die is off (call Lee-they will ask you to send them the die and a couple of cases and will fix it free), or your brass needs annealing.

If your bullets are lighter and shorter than the ones in the commercial loads, they may need a shorter C.O.L. to fit. The rule of thumb, if you aren't seating out to touch the rifling lands, is to seat the bullet one caliber (bullet diameter) beyond the depth at which the bullet stops when you just set in into the case mouth; the point at which the bullet reaches its full diameter. That will just be the bottom of the bullet for a flat base, but in a boattail design will be up where the boattail meets the full diameter bullet bearing surface. In a case where the neck is shorter than one caliber, you can just seat deeper by an amount equal to the length of the case neck, once the full diameter portion of the bullet has started into the case mouth.

If you are using a heavier or longer bullet than the commercial ammo, the maximum seating depth is determined by where the bullet bearing surface starts to narrow from full diameter onto the ogive. That point should not be seated any deeper than the case mouth.

If all else fails, I expect Lee makes a Factory Crimp die for this caliber, but it shouldn't be truly necessary. It may help accuracy by improving start pressure consistency, but you should save that experiment until after you have a basic load working.
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Old July 3, 2007, 01:39 PM   #3
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Unclenick beat me to it, so I erased my post.
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Old July 3, 2007, 03:19 PM   #4
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If your using a Lee seating die and you wish to crimp your load. Trim all your cases to the same length. Put a case in your press and run it all the way up. turn the die down until it touches the case mouth plus 1/4 turn. this will give you a slight taper crimp. Note! It is critical to have all your cases the same length for this to work properly.
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