Shoulder bump

[Spoonbill]

I have 100 once fired 243 Win cases I need to resize. After measuring with the Hornady headspace comparator four of the cases measure 1.617. 48 cases measure 1.618. 44 cases measure 1.619. The last four measure 1.620.

Which length do I set the die up with? Am I overthinking it that I want the length the same after I resize?
I recently bought the Redding competition shell holders thinking I could accomplish this task.

 

[Fairchaser]

Measure a piece of brass that has been shot with that action and barrel combination and then subtract .002. Resize new brass to that measurement. If there are several lengths, go with the longest or the ones most common. Usually, it takes several firings to get the correct headspace.

 

[rwj]

If you chamber the longest case, can you close the bolt without excessive force? It’s possible that none of them yet need to have the shoulder length set back.

 

[Spoonbill]

Measure a piece of brass that has been shot with that action and barrel combination and then subtract .002. Resize new brass to that measurement. If there are several lengths, go with the longest or the ones most common. Usually, it takes several firings to get the correct headspace.

I get that. My question is should I worry about the measurements being exactly the same. Like if I set up for the ones that measure 1.620 and bump them back .002 will that size the ones that measure 1.617? Or vice versa.

 

[jepp2]

If you chamber the longest case, can you close the bolt without excessive force? It’s possible that none of them yet need to have the shoulder length set back.

This ^^^^^^

 

[Spoonbill]

If you chamber the longest case, can you close the bolt without excessive force? It’s possible that none of them yet need to have the shoulder length set back.

How do I full length resize and not set the shoulder back yet?

 

[jepp2]

My question is should I worry about the measurements being exactly the same

No. And when you size the case and it squeezes the side in, it makes the case head to datum longer. So the short ones will become longer.

 

[Straightshooter1]

I have 100 once fired 243 Win cases I need to resize. After measuring with the Hornady headspace comparator four of the cases measure 1.617. 48 cases measure 1.618. 44 cases measure 1.619. The last four measure 1.620.

Which length do I set the die up with? Am I overthinking it that I want the length the same after I resize?
I recently bought the Redding competition shell holders thinking I could accomplish this task.

This is how I would approach it . . .

These are just once fired brass that'll have some spring back and it is likely that they'll be more uniform after the second firing, especially if you anneal them. Until they're fired the second time, I'd set my sizing die to bump the shoulder back .002 from 1.619. Then after the second firing, I'd make some adjustments in the die setting based on the results then.

 

[jepp2]

How do I full length resize and not set the shoulder back yet?

Start with the die above touching the shell holder when the ram is fully up. Start sizing and measuring. Lower a small amount then size again and measure.

 

[Spoonbill]

If you chamber the longest case, can you close the bolt without excessive force? It’s possible that none of them yet need to have the shoulder length set back.

1.620 has some resistance. 1.619 had none

 

[RustyInBend]

I set the die in the press with the ram up and using the touch point of the .010 shellholder with an extra 1/4 rotation of cam-over, and then size with the .004 shellholder. That consistently gives me about 2-to-3 1000's of shoulder bump. Works perfect for me every time and on all five calibers that I reload.

 

[Spoonbill]

This is how I would approach it . . .

These are just once fired brass that'll have some spring back and it is likely that they'll be more uniform after the second firing, especially if you anneal them. Until they're fired the second time, I'd set my sizing die to bump the shoulder back .002 from 1.619. Then after the second firing, I'd make some adjustments in the die setting based on the results then.

I will do this and report back. I appreciate all the responses. Im here to learn

 

[K22]

Remember, the only reason you are sizing is so: 1. the case will chamber without excessive headspace, 2. the case neck will hold the bullet. The following discussion is based on sizing for a bolt action rifle.

It's not uncommon in my experience to see some variation in fired case headspace especially with average quality cases and different rifles. Also, measurements are subject to operator error. In my experience, even after sizing, some variation in case head space often occurs, normally about .001" especially with newer cases.

Also, when you FL size a case, you are also sizing the radial dimension of the case which aid in chambering.

I would set the FL die to set back the shoulder on the 1.620 about .001" and see if it chambers. If it does, I would use this setting for the others. While it's true the 1.617 cases may tend to extrude especially in a case like the 243 Win that has no taper, if the shell holder is in contact with the ram, these cases may size without pushing the shoulder back or extrude a small amount but the case should chamber without any difficulty since they are still under the maximum head space.

I set up to err of the side of pushing the shoulder back the least amount only as much as necessary for the case to chamber without difficulty. One of the advantages of FL is the radial dimension is also sized which greatly aids in chambering. I've often FL sized with only .001" to 0 shoulder set back and the cases chamber easily. Again, the shell holder must be in contact with the ram.

Guys who neck size are sizing with zero shoulder set back. Often, they obtain several reloads without having to FL. So if you are FL with a small about of set back plus sizing the radial dimension, you should have no problem chambering the case or creating excessive case head space.

This assumes that cases are the same lot, brand and dedicated to a specific rifle and that cases are rotated in use to promote uniform working of the brass.

As cases age hardened, some die adjustment may be necessary to achieved the same shoulder set back. I typically measure three cases out of the group I'm sizing everytime I size to verify the die setting does or does not need changing. I also use Skim Shims to make adjustments but the shell holder is alway in contact with the ram no matter which size shim I use. The Shim merely adjust the amount of cam over thus the degree of shoulder set back. The competition shell holders operate on the same principle and are another device that can be used to make adjustments. I like the Shims since they are signficantly cheaper and can be used for any cartridge.

I use a single piece bump gauge - Whidden. It doesn't have any interfaces which might recreate measurement errors. With two piece gauges, placing match marks of the holder and insert will help assure that the gauge is assembled in the same alignment each time thus aiding in measurement consistency.

 

[Fairchaser]

I get that. My question is should I worry about the measurements being exactly the same. Like if I set up for the ones that measure 1.620 and bump them back .002 will that size the ones that measure 1.617? Or vice versa.

It will full size but not bump the shoulder on the shorter cases, which is fine. After several firings, they should all be close to the same.

 

[Spoonbill]

I just resized all 100 cases (Lapua once fired from my rifle). I started by screwing my die down to make contact with my shellhoder. When I make contact with my shell holder it will compress more. About an eighth of a turn. Thats where I judge contact.

I started with the .010 shellholder and after final adjustments the .006 sized it back to 1.617. Good deal. I wiped off the cases real quick and chamber checked them to be a good fit.
I next sized the 1.617 length starting with good results there. One case measured 1.616 and the others measured the same.
Next I sized the 1.618s and 1.619s. With the .006. All came out to 1.617 except for one or two.

I have been loading for a long time and wanting to learn the nitpickings and tricks that make good loads into great loads and I feel it starts with case prep.

It will full size but not bump the shoulder on the shorter cases, which is fine. After several firings, they should all be close to the same.

You just answered a huge question I had. Thank you

 

[Spoonbill]

Should I just get the tools to strip my bolt and set up my dies that way?
Are there any cons to that method?

 

[rwj]

Should I just get the tools to strip my bolt and set up my dies that way?
Are there any cons to that method?

Yes, get the tools needed to disassemble the bolt. Also suggest buying a spare firing pin/spring and an extractor. Setting up your sizing die using the stripped bolt method works well!

 

[Clancy]

I am pretty overwhelmed at the amount of ways people accomplish this task, but for me and a lot of others, this is the way.

Dont set them back more than .001 after the first firing, preferably not at all.

Set them back .002 after that.

I can’t see giving advice on how far to screw your die in if I don’t have your press in hand . I’ve seen where touching the shell holder wouldn’t move a shoulder and where touching the shell holder would move a shoulder back 10 thousandths. Don’t take any advice along those lines. Screw it down, back it off a turn and go down from there. (I’ve even seen this bump them a little but only once.)

Forster makes a lock ring with .001 marks on it.

measure, measure, measure.

Inconsistent base to shoulder readings aren’t strange on a first firing, especially when one case might have had 35 grains of powder and another had 39. They’ll even out.

This step (bump check) needs to be done at every loading, whether you anneal or not. They’ll change some as they harden, and they’re real easy to bump once you’ve annealed.

Have fun and shoot!

 

[Kracken McGraw]

The Redding competition shell holders mentioned above are really very handy.

 

[Spoonbill]

Yes, get the tools needed to disassemble the bolt. Also suggest buying a spare firing pin/spring and an extractor. Setting up your sizing die using the stripped bolt method works well!

Im going to get the tools on order. Thank you