Thread: Shoulder Bump Advice

Just after some advice for shoulder bumping brass.

I'm shooting 7mm Rem Mag, which after firing measures around 2.1200" with a headspace comparator.

I also tried some various lengths of brass in my chamber (firing pin out of bolt):
2.1200 inches chambers fine, bolt handle falls down
2.1215 inches chambers fine, bolt handle falls down
2.1230 inches chambers fine, bolt handle has slight resistance
2.1235 inches won't chamber

After resizing, my shoulder is growing out to 2.1230" - which still technically chambers, but is close to not.
I assume this will also cause an issue with the brass moving back and forth a lot.

So, I'm after advice:
What length should I be aiming my shoulder bump to be? 2 thou less than the fired length (2.1200") or the size that won't chamber (2.1235)?
I assumed screwing my die down would help move the shoulder back (rather than make it longer), but I'm already hard on the shell holder. Help?

Hopefully that's enough info! Can provide more as needed.
Cheers

there is an entire thread on this already ......... do a search bud

Screw the die down further & bump it back a couple thou shorter than your measured fired case.

Go off the size that won't chamber as that is what is important.
If its new brass it may take a few firings until you are actually doing much sizing.

Eric Cortina has a video on YouTube I'd recommend watching that. Simple and easy to understand.

If you want to get it spot on its a fairly fine adjustment on die.

Originally Posted by 6.5 CRD

Screw the die down further & bump it back a couple thou shorter than your measured fired case.

Didnt he say he was on the shell holder already?

Originally Posted by Fisherman

Didnt he say he was on the shell holder already?

You can still wind the die down further so it loads into the shellholder slightly when the press is at full stroke and thus bump the shoulder back further.

Originally Posted by Sonicjoe

Just after some advice for shoulder bumping brass.

I'm shooting 7mm Rem Mag, which after firing measures around 2.1200" with a headspace comparator.

I also tried some various lengths of brass in my chamber (firing pin out of bolt):
2.1200 inches chambers fine, bolt handle falls down
2.1215 inches chambers fine, bolt handle falls down
2.1230 inches chambers fine, bolt handle has slight resistance
2.1235 inches won't chamber

After resizing, my shoulder is growing out to 2.1230" - which still technically chambers, but is close to not.
I assume this will also cause an issue with the brass moving back and forth a lot.

So, I'm after advice:
What length should I be aiming my shoulder bump to be? 2 thou less than the fired length (2.1200") or the size that won't chamber (2.1235)?
I assumed screwing my die down would help move the shoulder back (rather than make it longer), but I'm already hard on the shell holder. Help?

Hopefully that's enough info! Can provide more as needed.
Cheers

I don't know what the issue is bud but I do know the rem mag with that belt can be problematic. Mine has a really loose chamber and my Redding body die would really struggle with resizing the brass while my Lee die was obviously a bit looser and was better, maybe excess brass is flowing into length.
Very soon the brass developed a bulge in front of the belt which made chambering difficult...sounds like you are doing some good measuring son that's not the issue.

From your notes 2.1230 sounds like it’s on the money, size to the that

If you brass is growing After resizing it’s likely that you are not lubing the inside of the case neck. This cases your brass to lengthen on the up stroke of the ram.


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Thanks for all the helpful replies.

I guess my main confusion is around what to size to. Seems pointless to bump the shoulder back further when its still chambering at the fired length.
Brass is around 3x fired, so not brand new.

Have been doing a lot of watching and reading (pretty much everything that has been suggested), but can never seem to find what to do if your fired brass size still has a whole lotta length that it will chamber with.

As I say, thanks again and I'll give some more things a try and see how I get on!

Remove the expander then size a fired case and measure to the shoulder , if the case has grown its the die that's the problem . The problem is caused by the case body being sized and the shoulder not engaging the die .
If it only occurs with the expander fitted , lube the inside of the neck .

The former is the more difficult to correct , with rimless cases it's possible to have someone machine a few thou' off the bottom of the die , with rimmed magnums it would depend on the rim clearance within the die . Otherwise, its time to buy ,beg or borrow.
Don't try to reduce the shellholder, it may weaken it to the point of failure , leading to a stuck case .

Greetings,
The tight spot on the shoulder in the chamber may not be where your comparator is measuring so go with the measurement where the case chambers freely. There is one thing to watch on belted cases is a tight spot developing on the body of the case just in front of the belt. This is due to loose tolerances for chambers and dies. The case can chamber with resistance but the shoulder is well short of the chamber. From your description you don't have a problem. Be thankful, others are not so lucky. Check your cases each load for signs of head separation as this can be a problem with belted cases. Cases grow in length when FL resized. The diameter of the case is reduced and with the press ram hard up its bum there is nowhere else for the brass to go, don't worry about it. Just trim to the right length. There are a number of reasons for cleaning and lubricating the inside of the case necks including keeping the necks concentric. Cases stretching due to a lack of lube is an old fable that refuses to die. Frequent tests have disproved this fable but it lives on.
Being an OCD type of chap I do decapping, case sizing and neck expansion as three different operations. De capping the case with a punch set allows the primer grit to be kept away from the die. Expanding the neck from the outside in with the standard button keeps the neck straighter than some standard dies. John Barsness did a test on this a while back. Keep asking questions and developing your skills. There are no stupid questions.
Regards Grandpamac.

Originally Posted by Sonicjoe

Thanks for all the helpful replies.

I guess my main confusion is around what to size to. Seems pointless to bump the shoulder back further when its still chambering at the fired length.
Brass is around 3x fired, so not brand new.

Have been doing a lot of watching and reading (pretty much everything that has been suggested), but can never seem to find what to do if your fired brass size still has a whole lotta length that it will chamber with.

As I say, thanks again and I'll give some more things a try and see how I get on!

If they are clambering without issue after 3 firings then I'd just stick with what you have.
You only need to size them enough that they chamber and eject without issue, excess sizing will just shorten the brass life unnecessarily.

Originally Posted by Sonicjoe

Just after some advice for shoulder bumping brass.

I'm shooting 7mm Rem Mag, which after firing measures around 2.1200" with a headspace comparator.

I also tried some various lengths of brass in my chamber (firing pin out of bolt):
2.1200 inches chambers fine, bolt handle falls down
2.1215 inches chambers fine, bolt handle falls down
2.1230 inches chambers fine, bolt handle has slight resistance
2.1235 inches won't chamber

After resizing, my shoulder is growing out to 2.1230" - which still technically chambers, but is close to not.
I assume this will also cause an issue with the brass moving back and forth a lot.

So, I'm after advice:
What length should I be aiming my shoulder bump to be? 2 thou less than the fired length (2.1200") or the size that won't chamber (2.1235)?
I assumed screwing my die down would help move the shoulder back (rather than make it longer), but I'm already hard on the shell holder. Help?

Hopefully that's enough info! Can provide more as needed.
Cheers

Sounds to me you are resizing too much.


Say,,,2.1227 inches. Just enough for the bolt to close, no more.