Shoulder Bump - what am I doing wrong?

[DJL2]

I'm "that guy" twice today. First, I must admit that I usually just FL size everything (x1!). Well, I got a shoulder bump gauge and a fancy sizing die for my 6.5 CM and got the notion that maybe I ought to try just bumping the shoulder. I've got old school calipers (i.e. analog). The bump gauge is just a shade under an inch (.994). I left as is in the photos (zeroed it when I did the measurements originally). Once fired cases measured between 1.528 and 1.530 (Hornady factory loads). Wanted to target 1.525. It took me a while to setup, but figured maybe I had things in hand. Bottom line - I've clearly goofed something up pretty considerably. I'm jacking up the case shoulder. For guy that usually just screws the die into the press and runs it, this is a bit perplexing. Figured I asked the group here for some help.

 

[918v]

You may have lube issues and or press linkage slop issues.

 

[spife7980]

Im just going to work with the numbers as presented on the caliper so I dont have to add shit.

2.521 goes to 2.517 at the extreme reading. Thats fine.

The reason for your divot in the shoulder is you have either
1. have too much lube or
2. you didnt let the carrier flash off and leave only the lube so you are shoving non compressible liquids up into the die with it which is why its buckling inward

 

[PowellSixO]

Lube

 

[DJL2]

Ok... I'll let my six year old run this so that someone competent is at the handle. Thanks gents.

 

[PowellSixO]

It didn’t hurt anything. Load em and shoot em.

 

[MtnCreek]

If I'm understanding your numbers, looks to me like you're oversizing them by about 7 to 11 thousandths.

 

[m1match]

@MtnCreek I think you misreading the numbers. It looks like the 2nd photo is of his case gauge before resizing and the 3rd is after resizing and it shows he's bumped the shoulder back a tad more than 3 thousandths, which is fine.

As for the dents in the shoulder, they are usually caused by 1) excessive case lube in the shoulder area or 2) like spife7980 said, you resized the cases before the volatile carrier in your case lube (usually alcohol) had time to fully evaporate.

 

[FLIGHT762]

I'll also chime in on the too much lube crowd.

Shoulder dents in your photos are caused by too much lube in the die and the excess lube gets pushed up to the top and dents the shoulder.

Clean the lube out of your die out and ease up on the lube. Check your F/L die to see if it has a vent in the side that can become clogged and that can also cause your issue. Some dies have the vent, some don't. A straightened paper clip will work.

We've all had it happen and corrected it.

Go ahead and shoot the brass, it won't hurt anything.

 

[DJL2]

You all nailed it as near as I can tell. Hit it with some parts cleaner, relubed and dried thoroughly, seemingly no issues this evening. Here’s to hoping I don’t do something similarly stupid with my seating die ;-).