Shoulder Bump

[semomike]

Annealed 6.5cm Hornady 1 fired brass, Redding UltraMag, Redding SMALL BASE die

Guys, I'm reloading for a POF gas gun and trying to achieve a consistent .003 shoulder bump.

I'm getting at least a a variance of .003 measured with a Mitutoyo caliper and Hornady case bump gage .375 without moving the die. I'm verifying that all case are approximately 1.5620 before sizing, and getting some wild changes. Sometimes even as small as 1.535. The press is camming over, and am using a very small amount of unique on my rubber gloves prior to sizing. Sometimes I will achieve the desired 1.5950 I'm shooting for.

What the heck am I doing wrong? I'm assuming it's spring back, but I thought annealing was supposed to help with this!

Yes, I meant 1,5535, and I flame anneal. I usually shut out the lights when I anneal, putting the inside flame almost touching the shoulder, and setting my time till the brass just starts glowing red

 

[semomike]

I have a set of burst fire inside neck diameter “pin gauges” and use the .291 (I think, I’m not at my bench) neck bushing (special order Small base type s Redding die) to try to achieve about 3 thou in neck tension. I’ve struggled getting neck tension to be consistent when don’t use an expander ball. My process is measure case length with .375 Hornady gauge, bump the shoulder with the press, check neck tension with the pin gauge, measure the shoulder bump achieved. I use different pieces of brass to zero in. As soon as I achieve my results (usually 3-4 pieces of brass) I will just run with it checking periodically with the pin gauge and bump gauge.

Maybe I’m under lubed (always a problem!!!!!). I usually put a very small amount of unique on my gloves and give the brass a quick spin in my hands n the way to the press.

I also try to remove expander ball and see what kind of results I get this time on neck tension and shoulder bump.

 

[Link]

I make my adjustments with "THESE" ... it solves that for me. Trying to get it right without adjusting the shell-holder, can be really hard sometimes.

No other good way to do it, if you want to bump camover.

 

[One Eye Pete]

Another quick tip. If you want to get away with using a minimal amount of case lube try polishing the inside of the sizing die. I do this with almost all of my sizing dies and it makes a huge difference especially on a small base die where you are squeezing down even more. It’s a simple procedure, I use a piece of paper towel wrapped around a wooden dowel until it fits snugly into the die. I coat the paper towel with either Flitz or White Diamond metal polish and work it around inside the die until it has a mirror like finish. It takes about 20 minutes but makes a bid difference in the force required and amount of lube needed for sizing. No it doesn’t affect the die dimensions as you are only removing the roughness of the metal surface.

 

[ELR LVR]

When I push the brass up into the die I always pause 4-5 seconds. This will help with springback and you'll get more consistency. As others have said, watch for lube on the shoulders a make sure you're not getting lube buildup inside the die. Die might need to be cleaned.

Good tip I sometimes forget to do
Takes a second for brass flow

 

[DJSBRS]

When you anneal make sure you have enough heat on the shoulder and not just the neck itself. If you are flame annealing and the flame in only hitting the neck the shoulder may not be getting hot enough and giving you some spring back. I like to point the flame at the shoulder just slightly behind the neck shoulder junction.
The other thing is check your press. I don’t let my press cam over, I use a hard stop. You can also do this by using Redding competition shell holders and always have the shell holder touch the bottom of the die when sizing. This helps minimize inconsistency with the press. Also as mentioned above no lube on the shoulder. Also as mentioned above I never use an expander ball just a good bushing die or a standard die and then a mandrel.

Exactly!

DJ