Is it the leading edge or the base that is too big? MEC single stage presses don't have a separate taper die like their progressives. My 600 makes shells that I have to push in to my O/I and they don't feed well in a semi auto. Sizemaster should definitely resize the brass base so it's probably your top edge. I've seen folks say MEC 600 and Sizemaster can be adjusted to put the leading taper on the crimps but the manual doesn't directly explain how.

 

Yep, it's the leading/top edge. The brass is sized perfectly. When I ream the end of the completed shell with my sizer, it chambers perfectly. And when I say "the end", I mean just the top 1/4" needs to be tapered down.

A buddy of mine has a completely separate press with a special sizer die to taper his, but I was hoping I could configure the MEC Sizemaster to do this without buying more equipment.

 

Take a look at this thread

Better Taper

I load on an older 600 Jr. and was wondering if anyone was aware of a die or way to impart a better taper on the finished shell. I'm getting great crimps with the current set up but would like to try and get a little more taper since I shoot a Model 12 and automatic at times. I'm not ready to...

www.trapshooters.com

Sounds like you need to adjust the cam down a little. You might get a bit of swirl if the cam is down enough to give a good taper.

 

Thanks, I think this is going to be the solution. I will post back tomorrow to let you know. I appreciate your help

Edit: I might call MEC and ask about this:
"I still wasn't getting the result I wanted, especially on Federal hulls. I bought a taper crimp die for a Mec 9000 and swapped it out for the final crimp on my 600 Jr and ran the loaded shells through this additional station and got a really nice taper. Really didn't take to long to do it. "

 

The Sizemaster‘s last die does both the final crimp and the taper. Try lowering the final crimp a tiny bit. You are looking for .05 depth of the crimp. It’s a balancing act on the Sizemaster with pre crimp and final crimp.

 

Agree with the above about the sizing/taper die. The shells appear to have a slight mushrooming. The checker you are using is used primarily by cowboy shooters. If the round does not fully seat in the checker when you put the hull in the opposite end it is not reaming anything. What it is doing is adding some taper to the round.

 

Could you highlight in the photo where you see mushrooming?

 

Will it drop into the chamber of your gun? If so, don't worry about it.

 

Beat me to it! I'm amazed at times how a problem isn't a problem till you make it one. I started loading on a lee hammer powered die set at 12 years old. They worked fine in my gun and I've never used a chamber gauge for any shotshell. If it fits your gun SHOOT IT!

 

Unfortunately with competitive shooting where fractions of a second count, it's not as simple as "if it fits, you're good". I shoot these out of a double barrel and it has to fall in with no resistance whatsoever, or things can start to go wrong. Also, it's not just about "will it fit" it's about "will the damn thing come out easily too". A bad crimp can cause stuck hulls on a shuck.

EDIT: I'm talking about cowboy action shooting, sorry I didn't mention that earlier.

 

Unfortunately with competitive shooting where fractions of a second count, it's not as simple as "if it fits, you're good". I shoot these out of a double barrel and it has to fall in with no resistance whatsoever, or things can start to go wrong. Also, it's not just about "will it fit" it's about "will the damn thing come out easily too". A bad crimp can cause stuck hulls on a shuck.

What type of shot shell shooting sport does seconds count? Are you talking 3 gun? Cowboy? We here are trapshooters. We take our time. If I were shooting a shot shell sport where seconds count, I would be shooting factory.

 

Get some scales, don't rely on bushing charts

 

You need to lower the cam adjustment. You should back out the depth adjustment. Get the taper correct. Then lower the depth. Otherwise you might start crushing hulls. As stated it's a balancing act. Between the three adjustments.

 

My sizemaster's don't have that problem, same collet as my Grabber's.

 

Thanks for everyone's tips and advice. I was able to find a good balance between the punch depth and cam setting. Now I have a nice taper that drops into the chamber checker. I also went ahead and bought the QuikLoader die just to check it out! Thanks!!

 

I mounted the QuickLoader to an old Mec case conditioner. I run all my cowboy shells through it even if they drop in the case gauge just to make sure they have the best chance of shucking reliably.

 

Glad you got it fixed. I had about 6 months or more of reloads made before I noticed the same thing on AAHS hulls. So for quite a while I would just push the mushroom tipped shotshells into my barrel, using the chamber as the ultimate final sizing die and hull checker. LOL. . I had to deepen the crimp and lower the final sizing die. I may still get one every now and then, but rare enough to not bother changing anything.

 

I find it curious talking about stuff like chamber checkers that don't really matter but the OP mentions bushing numbers instead actual drop weights. Seems like putting the cart before the horse to me.

 

stuff like chamber checkers that don't really matter

Shell dimensions do not matter? They matter if you are shooting a semi-auto (like my Butler) or trying to speed load a double barrel in a cowboy match.

 

I would say the hulls where fired in a over sized chamber gun maybe. A 9000 Mec could resize them back to factory spec with the right collet adjustment.

 

He has a crimp issue. Not a sizing issue.
Some of you need to go back to the beginning. Take that chip off your shoulder. Actually read and look at the picture.

 

He has a crimp issue. Not a sizing issue.
Some of you need to go back to the beginning. Take that chip off your shoulder. Actually read and look at the picture.

The OP even said his crimp looked pretty good. You are reading into this just like others have.

 

On the left side of a MEC Sizemaster, looking at it from the front of the loader, near the final crimp station there is an Allen head screw with a washer and the arm of the loader has a slot machined in it. Loosen the screw and push the arm so the so the screw is able to slide in the slot. The first few times you do this it will take a little pressure to move the arm in order to slide the screw from one side of the slot to the other. After you do this a few times it will be much easier. I found that it takes a littke more pressure to close the crimp. this is normal. This is how you put a taper on a hull with a Sizemaster. Why they don't explain this in the instructions is another story.

 

The reason the directions don't tell you that. Is that's not how the crimp die works. You don't know what your doing.

 

The pic isn’t the greatest but it doesn’t show whether it’s a good or bad crimp. Certainly not clear enough to answer as emphatically as you have.

 

The shell stopped before falling in. (The gauge). The part that is sized by the machine. Hasn't entered the gauge yet. The crimp is nail headed. Not tapered. Try reading post number 3. He confirmed this.

 

Buy a Grabber. Better crimp and faster.

 

It definantly looks like crimp issue,

A quick call to MEC support will breeze you through this,

DGH

 

Once one understands the adjustments for the crimp die. How the relationship of the adjustments work together. It's not a problem to adjust. 600jr/ sizemaser both can be adjusted to have a nice tapered crimp.