MEC 600 JR Mark V Station 1 Adjustments
 

Morning all, this may be a dumb question but here it goes. I have a post 1995 600 JR Mark V set up for 12 gauge shells. Station 1 (de-priming/case sizing) station does not properly resize brass on the shells. I have looked on line at MEC adjustments as well as following the limited directions in the manual for this station. However, when I check the brass sizing in a MEC Shell Checker the brass is still slightly to large to fit. At first I thought it may be the particular once fired hulls I was using (RST) but I also checked w/Remington STS once fired hulls and I get the same results.

To make sure I wasn’t losing my mind I resized them in a different 600 JR Mark V that I have and they resize properly. Any thing I’m missing or any suggestions would be appreciated. I may end up ordering new parts for this station but wanted to check before I did as this unit is in good condition and has seen little use. Thanks - Brett

As a test I swapped out the collar on the reconditioning dies and the shells resized correctly so it leads me to assume I have a defective collar. I believe I can order that part instead of the whole reconditioning die.

Brett,

Give MEC a call. They are very helpful. 800-797-4632.

Is the wire ring inside the collar? That ring is what actually sizes the brass on a 600Jr.

Edgar, I looked at both the resize rings (part #20 on the diagram) and MEC Part #8465 and there is not wire ring inside either one of them. I’ll call MEC tomorrow and see what they say. Thanks!

The resizing ring on a MEC600 is a wear item. They wear faster when reloading hulls with steel heads rather than brass but they do last a long time.

They are gauge specific. It's 20A for 12ga. https://www.mecoutdoors.com/600-jr-mark-5-parts

My mistake. That was only one the earliest version.

Thanks everyone for your feedback. I’ll order two to have an extra on hand. Brett

Forgot to mention that I ordered new resizing rings. Before I left for Tulsa last week I loaded a box of shells and the new resizing ring worked great. All of the shells were in tolerance. Thanks for everyone’s help! Brett