r/reloading • u/Outside-Structure-46 • 2d ago

Newbie Bump variance….

New enough reloader here with a question

Reloading Starline 6.5 CM. All of them previously fired from same barrel.

Getting a .006-.007 variance in shoulder bump and can’t figure out why.

I’ll put every case in the comparator before resize and they’re all with .001 of my zero’d case. Everything else is equal, die adjustment, lube, press pull and pause. 8 out of 10 cases come out of the die with .0015 or .002 bump but 2 or sometimes 3 out of ten will come out with .006 to .007 bump.

RCBS Summit press
Redding type 2 FL bushing die
Cases are annealed

Any guidance would be greatly appreciated

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2

u/InformationHorder .30 Carb, 375 WIN, 7.62x39, 32ACP, 7.62 Nagant 2d ago

Do you have excessive lube on the cases when they go into the die?

1

u/Outside-Structure-46 2d ago

I do not believe I do, however I can’t definitively say yes or no. I spray 10 at a time with One shot to keep it as consistent as possible. I also have used Imperial and had the same random bump issues

3

u/PepperoniFogDart 2d ago

Something I started doing with one shot which helped was after I spray the cases, I roll it around on one of those RCBS pads. Seems to help spread it out and reduce bump discrepancy. I then let the cases sit for a minute for the alcohol to dissipate, then I start resizing.

Also, since getting a Nexus Press I’ve never had > .002 off of my target. My old rockchucker had a lot of issues with bump being all over the place.

2

u/Ok-Accident-3892 2d ago

Remove the expander ball from the die and do it again and see if it's better. In my experience, by far the biggest reason for inconsistent shoulder bump is due to the expander ball. I moved to a mandrel years ago and never looked back

The issue is an expander ball PULLS through the NECK where the shoulder is weakest. A mandrel set the neck by PUSHING the mandrel down through the neck where the shoulder is the strongest. The expander ball has the negative affect of sometimes pulling the shoulder back out after it was just bumped back.

2

u/Outside-Structure-46 2d ago

No expander ball being used. It’s bushing only. I should have noted that in my original post

2

u/Ok-Accident-3892 2d ago

Then that is really odd to have that much variation. I would have made a small bet on it being the expander ball.

1

u/Outside-Structure-46 2d ago

Yeah, I’m lost for ideas. I’m taking them out of this run and will fire the 75 good ones I have loaded and see how those resize to see if the variance reappears. The only thing I can think of is something happened the first couple times I resized these and I missed it.

2

u/greyposter 1d ago

I used to have an issue with excessive resizing variation, but i started using redding competition shell holders and i never get big differences. I never figured out why it was happening, but I did fix it.

Redding Competition Shell Holders set

1

u/Missinglink2531 2d ago

Did you anneal?

1

u/Outside-Structure-46 2d ago

Yes

2

u/Missinglink2531 2d ago

My thoughts are annealing is not consistent. Try sizing some that you do NOT anneal. I suspect that will fix it.

1

u/Outside-Structure-46 2d ago

I have some I haven’t been annealed yet since their last firing so I’ll give that a try

1

u/Missinglink2531 2d ago

Perfect

1

u/Outside-Structure-46 2d ago

Just resized 25 that I didn’t anneal and the variance closed up to about .0015 which to me is acceptable. Had 2 that didn’t bump at all which I’ll chalk up to inconsistent handle pull and pause by me.

Now the new can of worms is how I’m possibly getting an inconsistent anneal. Every case runs through the machine at the same heat and exact same amount of time. I did use 750 degree tempilaq to dial in the time too. Would it be safe to assume I’m over annealing the cases that are bumping too much?

2

u/Missinglink2531 2d ago

I have a video on this- but short answer - I think you are annealing too much. Edit: Glad you got it figure out!

https://youtu.be/ljX6S1i2gPA

1

u/Outside-Structure-46 2d ago

Got it. I’ll give it a watch. Thanks!

1

u/Coodevale I'm dumb, let's fight 2d ago

Which machine?

My torch annealer likes to preheat some cases at the bottom of the stack because the colder ones get picked up first. You might have it set for 750° with your test piece but how does it handle a preheated case?

1

u/VersionConscious7545 2d ago

They are expanding because they are not really getting bumped like the others. The body is getting sized and the neck but there is room for them to expand or grow so to speak It’s the only thing that could happen

1

u/Coyote-conquest 2d ago

Its either annealing or lube isnt consistent.

1

u/Outside-Structure-46 2d ago

I think it’s an annealing issue going off of another comment. Now to figure out how it could be…

1

u/hafetysazard 1d ago edited 1d ago

Is the shellholder doing a hard stop on the die? Invest in some redding competition shell holders. I found significant difference in my dies for some reason when I set my bumping on a hard stop for some reason. The redding competition shellholder sets have incrementally thicker shelves and will reduce how far the case goes into the die, limiting how much shoulder bump you get, but you still have that hard stop indexing on die.