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 Post subject: Re: Wad Selection And Roll Crimping
PostPosted: Fri Jul 31, 2020 9:05 am 
Field Grade

Joined: Thu Oct 04, 2018 4:22 am
Posts: 70
Hal4son wrote:
Put an overpowder card under the plastic wad. It'll stop the powder migration. None of the hodgdonreloading.com recipes specify roll crimp. Roll crimping will reduce pressures slightly.

Curious, are you going Longshot in a 3" Fiocchi hull or the 2-3/4" Clays recipe?


This suggestion is not a good one. Placing an overpowder card under the plastic wad will lift the wad by the depth of the wad's cupped bottom; increasing the stack height. You won't be able to crimp the shell. -Ed




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 Post subject: Re: Wad Selection And Roll Crimping
PostPosted: Thu Aug 06, 2020 9:15 am 
Crown Grade

Joined: Mon Mar 28, 2005 11:25 pm
Posts: 2186
Location: Attica, Mi
In reply to the post that he can't get his 600 Jr to put a good tapper on the end of the shell so it'll feed in a auto - you just have to adjust it properly. I've posted this before - it's two different post others made and I saved.
When adjusting the crimp station, the CAM is the LAST thing you adjust. Adjust the crimp starter first, then adjust the seating stem to get the proper depth. When you are getting a correct fold of the crimp petals, and the correct depth set, THEN adjust the cam to eliminate the flare. NOTE The cam adjustment should be set at least 2/3 of the way up, while the other adjustments are being made. Then, and only then, lower the cam enough to eliminate the flare.


The roller will not touch the cam (or at least not have any force put on it by the cam) at the very bottom of the stroke. BUT, more cam means the cam will touch the roller and apply force to it longer (further down) in the stroke. The cam has a fairly sharp shoulder or lobe on it. When you start down with the press the roller rolls on the cam (because this part of the cam is circular) and the outer (plastic) part of the die is pushed down by the cam and roller. Until you get around 1/2-3/4 of the way down, everything I have said so far remains true regardless of where the cam is set. However, the cam is rotating as you come down. Eventually the cam rotates to the point when the roller goes past the shoulder on the cam. Past this point the cam is no longer circular. As you come on down the cam puts less and less pressure on the roller. But, the center punch will come on down because it is fastened solidly to the top of the press. If the roller gets past the shoulder of the cam too early in the stroke you will end up with the punch coming on down on the center of the crimp and this tending to squeeze the top of the shell outward. But the plastic part of the die is not coming on down, which means it cannot prevent the top of the shell from flaring outward. It takes a lot of fine tuning to get this just right. There is a reason why Mec adds the final taper die to the Grabber and 9000. Having a separate die that is used strictly to get some taper makes things a lot simpler.

Most people do NOT have straight in their minds what the CAM actually does. There are all kinds of convoluted beliefs as to what it actually does.

Adding more cam, (Lowering it at the adjustment slot), causes the crimp die to lower slightly at the near bottom of the stroke. The die has a taper at the top of the die, that when pushed lower, will in fact push the flare at the end of the hull inward, closing the hole in the center tighter, and usually will eliminate the flare and in fact may leave the end of the hull slightly rounded.

SO, in most cases, a properly adjusted CAM will reduce or eliminate the flare on the end of the hull, and probably leave it slightly rounded.

_________________
Venue shotgun chairman of the LCSC and the LPSXSA


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 Post subject: Re: Wad Selection And Roll Crimping
PostPosted: Thu Aug 06, 2020 7:51 pm 
Crown Grade

Joined: Tue Jun 15, 2004 11:55 am
Posts: 4777
Location: Hemingway, S.C. 29554
Bladesmith,
Very good reply & explanation! I am not currently having that issue but I am going to print this & put it in my file for future reference.
Thank you!


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