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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!
 
I assume you meant to type "1.559" as your goal measurement, correct?

Also, if I am reading that correctly, you are having some that read 1.535" after sizing? So, almost 30-thousandths of bump? I would suspect a measurement error or there is an issue with your setup.

In my experience, you shouldn't have much cam-over if only trying to bump 0.002-0.003". If you are getting hard cam-over, that may be your issue.
 
semomike said:
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!
Click to expand...
Why the small base die?
 
The lube is the mostly culprit as said above by a few. There needs to be enough and it needs to be applied consistently to get consistent results.
 
semomike said:
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!
Click to expand...
How are you annealing? If it shoots good don't worry about bump.

Added later:
Not an expert on pin gauges but I wouldn't think a precision gauge should be used on a textured surface. The one single high point would be a no go. Expander mandrels push the shoulder down, expander balls pull the neck up. I would guess whether it's a fL die or a bushing die you are pushing down on the neck. I get 1 to 1.5 thou variation annealing red and a bushing die.
 
Last edited:
1-more lube on the body,shoulder really doesn’t need any.
2-are you truly annealing enough?
3-are you using a expander in the sizing die?
If the die is really sizing the case heavily (especially the neck) the expander on the up stroke can deform the shoulder.
 
HandgunHTR said:
I assume you meant to type "1.559" as your goal measurement, correct?

Also, if I am reading that correctly, you are having some that read 1.535" after sizing? So, almost 30-thousandths of bump? I would suspect a measurement error or there is an issue with your setup.

In my experience, you shouldn't have much cam-over if only trying to bump 0.002-0.003". If you are getting hard cam-over, that may be your issue.
Click to expand...
I agree with ^^^^

Your system may be setup properly and bumps are consistent but your math is not consistent.

The use of calipers must be consistent.

Let us know what you find out.
 
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.
 
One Eye Pete said:
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.
Click to expand...
^^^^
I had a similar issue with my 338, was spoiled by my lil cases like 6bra and 22 arc and wasn’t getting proper heat in the shoulder.
 
semomike said:
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!
Click to expand...
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.
 
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