Full length resizing help - 6.5 Creedmoor

[Ghillie21]

So I've got 50 cases of fired Hornady 6.5 Creed brass or so, that I shot out of MY rifle. I followed a guide saying to full length resize all my cases to around 0.001" to 0.002". While doing this I feel like my calipers weren't too great, and I wasn't being as precise as I could have. Some cases had up to .004" bump. This started getting me worried that I may be bumping the shoulders back too much. I did some more research into what shoulder bumping actually does and I'm left with some questions I'd like answered still.

1. All of my fired cases still fit inside my chamber just fine before they were even resized. In this case, in the future, is it necessary to bump the shoulder back 1-2 thousandths if the brass still chambers easily?

2. I'm more than okay with throwing out these cases if I've messed up and potentially caused a dangerous situation by bumping the shoulders back too much. Does this extra shoulder bump seem dangerous to anyone? (Max of 0.004-0.005 thousandths bump off fired cases that already chambered just fine in my rifle.)

3. Is measuring the shoulder bump of a go-gauge that I used to chamber my rifle a good idea? If my fired cases have comparable shoulder bumps to a go-gauge, surely that would be safe? Correct me if I'm wrong!

Thanks for any help I can get!

 

[DownhillFromHere]

I suggest the Whidden Case Gauge, which gives you actual before & after measurements. My 6.5CM experience has been that factory rounds come in at around -0.002 to -0.003"(range 0.000 to -0.004 for what I checked), cases fired in my rifle are +0.002, and 0.00" is my base-to-shoulder target. Different makes of brass might - MIGHT - require slight adjustment of the seating die to hit the "target" due to different brass thicknesses as well as hardness/springback (open the can o' worms called annealing).

If you bumped the shoulder back to an extreme amount, excessive headspace might actually lead to misfires*. Too much working of the brass results in premature head separation.

If you have this gauge, you have good numbers to work with and it'll all fall into place. Good luck!

* Edit: This is unlikely to the point of I'd be amazed if it ever happened because no sizing die I've ever encountered screws down far enough to come close.

 

[CK1.0]

1. Yes. Guys who neck size don't bump back the shoulder, but they are dumb and their groups are shitty.
2. No.
3. No and yes, should be safe, but this has nothing to do with the go-gauge really, this is about bumping back the shoulder on fired brass.


A .004-.005" bump isn't the end of the world, it's not ideal but that's probably what most dies are when guys just screw them down until they hit the shell plate and start rolling. That amount of bump is just more than you need, so it leaves more room for the brass to expand in the chamber upon firing... thus working it harder than you need to, and potentially shortening the brass life by leading to premature case head separation.

~.002" of bump seems to be the "goldilocks" amount, it'll chamber nice and easy every time, but won't grow too much upon firing.

You need a precise way to measure your shoulder and figure out exactly how much to bump, there are a few different tools out there for the job, pick the one that makes the most sense to you. You want to measure your fired brass, not your go-gauge, and subtract .002" from that. Use your calipers and mess around for as many tries as it takes to setup your FL sizing die perfect, be precise (we're talking thousandths here lol) then lock down the lock ring, it can be a pain in the ass sometimes (Erik Cortina has a good video of how to do this on YouTube).

FWIW, I use the Hornady comparator and comparator headspace bushing (.375 for 6/6.5 creed):

Lock-N-Load Bullet Comparator Body

Lock-N-Load Bullet Comparator Body By HORNADY RELOADING TOOLS ITEM DECRIPTION For use with the Hornady Lock n Load Bullet Comparator Body Inserts and the Lock n Load Overall Length Gauges (not included).. Specifications & Features: This is the comparator body only. Bullet inserts sold...

www.midsouthshooterssupply.com

Lock-N-Load Cartridge Headspace Bushing .375 Diameter

Lock-N-Load Cartridge Headspace Bushing .375 Diameter by HORNADY RELOADING TOOLSFor use with the Lock n Load Headspace Gauge.

www.midsouthshooterssupply.com

 

[Ghillie21]

1. Yes. Guys who neck size don't bump back the shoulder, but they are dumb and their groups are shitty.
2. No.
3. No and yes, should be safe, but this has nothing to do with the go-gauge really, this is about bumping back the shoulder on fired brass.


A .004-.005" bump isn't the end of the world, it's not ideal but that's probably what most dies are when guys just screw them down until they hit the shell plate and start rolling. That amount of bump is just more than you need, so it leaves more room for the brass to expand in the chamber upon firing... thus working it harder than you need to, and potentially shortening the brass life by leading to premature case head separation.

~.002" of bump seems to be the "goldilocks" amount, it'll chamber nice and easy every time, but won't grow too much upon firing.

You need a precise way to measure your shoulder and figure out exactly how much to bump, there are a few different tools out there for the job, pick the one that makes the most sense to you. You want to measure your fired brass, not your go-gauge, and subtract .002" from that. Use your calipers and mess around for as many tries as it takes to setup your FL sizing die perfect, be precise (we're talking thousandths here lol) then lock down the lock ring, it can be a pain in the ass sometimes (Erik Cortina has a good video of how to do this on YouTube).

FWIW, I use the Hornady comparator and comparator headspace bushing (.375 for 6/6.5 creed):

Lock-N-Load Bullet Comparator Body

Lock-N-Load Bullet Comparator Body By HORNADY RELOADING TOOLS ITEM DECRIPTION For use with the Hornady Lock n Load Bullet Comparator Body Inserts and the Lock n Load Overall Length Gauges (not included).. Specifications & Features: This is the comparator body only. Bullet inserts sold...

www.midsouthshooterssupply.com

Lock-N-Load Cartridge Headspace Bushing .375 Diameter

Lock-N-Load Cartridge Headspace Bushing .375 Diameter by HORNADY RELOADING TOOLSFor use with the Lock n Load Headspace Gauge.

www.midsouthshooterssupply.com

So in my case, I've already resized my brass, can I go ahead and fire these rounds, knowing they are a bit off and may shorten brass life, and correct the mistake next time I resize?

Surely one firing with a slightly higher bump isn't gonna hurt.

And thanks for the advice! Greatly appreciated.

 

[2aBaC̶a̶]

How are you measuring the shoulder?

That whidden case guage is tits, i have one. They also makes a comparator like the hornady one.

Your fine, load it and shoot it.

Shoulder bump isnt always neccesary. Its a rule of thumb. If cases still fit with no resistance then they probably havent fully formed to the chamber.

 

[CK1.0]

So in my case, I've already resized my brass, can I go ahead and fire these rounds, knowing they are a bit off and may shorten brass life, and correct the mistake next time I resize?

Surely one firing with a slightly higher bump isn't gonna hurt.

You're fine and brass is resilient, I wouldn't worry about it.

 

[Ghillie21]

How are you measuring the shoulder?

That whidden case guage is tits, i have one. They also makes a comparator like the hornady one.

Your fine, load it and shoot it.

Shoulder bump isnt always neccesary. Its a rule of thumb. If cases still fit with no resistance then they probably havent fully formed to the chamber.

Measuring with the Hornady comparator. I got a real pair of calipers and my measurements seem a lot more accurate now. I still bumped way more than the rule of thumb this first time, but I'm going to go ahead and load these and correct the mistake next load. Thanks all!