Getting your Crimp right with MEC sizemaster.

[Joe from MO]

My question is, how to you get the whole crimping thing set, without messing up several shells in the process.

I am new to shotshell, and it just seems the only way to get all the adjustments right, is by trial and error.

I have just not seen any good instructions or videos on how best to do this.

[J. A. EARLY]

Just my two cents, but whatever shell I am loading I take a new shell and adjust to that as a starting point. If it is a Winchester AA hull, and my load is filling up the shell correctly with the wad and shot at the proper height, I'll put a factory load in there and feel them out by moving the settings to the factory crimp.

[Joe from MO]

Thats a good idea, thanks!

[Paul Harm]

With a progressive press there's another station for final crimp that makes things a lot easier. The single stage presses take a little fiddling. I make sure I'm using enough start crimp - the folds almost touching. From there on read the following I copied from another forum. These instructions should be included with the others, but sadly aren't. There are two different threads copied. Good luck.
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.

[Kevin McCormack]

The second sentence of your original post will answer 99.5% of your questions. Being a firm believer in the "learn by doing" approach to anything mechanical, experiment with the settings until you hit the "sweet spot" for a given hull/load combination. Yes it takes a while but well worth the time and effort invested.

[Joe from MO]

I am going to be putting together some new Bismuth loads for my Trojan, and am just trying to minimize collateral damage in getting the crimp sorted out.....

Thanks for all the input, some solid advice given here.

[Paul Harm]

The first thing I usually do with new loads is to measure how high the shot is inside the shell. It's hard to do if you're just starting out with nothing to reference it to, but the top of the shot should be just barely below the old crimp. Once you start getting nice shells measure it for future shells.