Achieving ideal case length with fired brass

[jjohnsonElknewbie]

Hey guys, is achieving ideal case length as simple as measuring fired brass from your rifle and then setting up your FL sizing die -.003 this measurement?

 

[49ereric]

neck size cases until fired case’s won’t chamber and then bump 2-3 thousands.
just watch the length after each firing and Trim as needed.

 

[Castle Rock]

Yeah I neck size almost exclusively using collet dies
You don’t have to worry about cases growing
I often go 10 reloads before FLS

 

[SDHNTR]

Hey guys, is achieving ideal case length as simple as measuring fired brass from your rifle and then setting up your FL sizing die -.003 this measurement?

On belted mags, I usually fire 2-3 times neck sizing only before then bumping shoulders .001-.002". You'll know when cases have fully grown when all the base to shoulder measurements are the same. On standard cases, I fire once and then proceed as above.

 

[Blackdog317]

On belted mags, I usually fire 2-3 times neck sizing only before then bumping shoulders .001-.002". You'll know when cases have fully grown when all the base to shoulder measurements are the same. On standard cases, I fire once and then proceed as above.

Same for me as described above

 

[jjohnsonElknewbie]

Thx guys, so based on this unanimous consensus I need to pick up a neck sizing die and move forward. Thanks again!

 

[SDHNTR]

Thx guys, so based on this unanimous consensus I need to pick up a neck sizing die and move forward. Thanks again!

You can neck size with a regular full length die. Just don’t turn it down as far.

 

[jjohnsonElknewbie]

You can neck size with a regular full length die. Just don’t turn it down as far.

That would save me some money. Can a guy decap and neck size in one operation in a regular FL though, or do you decap in a separate operation?

 

[SDHNTR]

That would save me some money. Can a guy decap and neck size in one operation in a regular FL though, or do you decap in a separate operation?

I hand decap, but depending on the FL die, you could just adjust the decapping pin lower and probably still pop em out while only neck sizing. Try it.

 

[B23]

You can neck size with a regular full length die. Just don’t turn it down as far.

You sorta can but it's better to use a true neck size only die.

Years back I used to think you could too but if you measure the base to shoulder datum before and after you try and neck size with a FL die, often, you'll get a longer measurement after you run it through a FL die you're trying to neck size only with. When people try and neck size only their brass with a FL die by backing it off is when you start hearing people talk about how neck sizing only caused hard bolt closure.

 

[SDHNTR]

You sorta can but it's better to use a true neck size only die.

Years back I used to think you could too but if you measure the base to shoulder datum before and after you try and neck size with a FL die, often, you'll get a longer measurement after you run it through a FL die you're trying to neck size only with. When people try and neck size only their brass with a FL die by backing it off is when you start hearing people talk about how neck sizing only caused hard bolt closure.

I’ve done it a lot and haven’t noticed this.

 

[jjohnsonElknewbie]

neck size cases until fired case’s won’t chamber and then bump 2-3 thousands.
just watch the length after each firing and Trim as needed.

So I FL sized around 200 once-fired .30-06 cases with my .25-06 sizing die without any problems. However, I noticed that all of the .30-06 brass is from 2.499-2.505 after sizing to SAAMI spec. re: set up sizing die so that shell holder was just contacting the sizing die. The brass will chamber with some difficulty.

However, The once-fired .25-06 brass is pretty consistently 2.492-2.494 right at SAAMI spec. of 2.494 max and chamber easily.

Question: can I screw down the FL sizing die to continue bumping the shoulders back on the reisized .30-06 brass until the cases chamber without issues? Or, since they are already beyond SAAMI max after FL sizing I need to trim to achieve the proper length?

Thank you all for the patience, clearly I'm a newb, and there is just a ton of different thoughts on this stuff in my research.

 

[logem]

It's possible, but unlikely, that you are experience trouble while chambering due to the case length being slightly over max length. Most chambers have enough throat that they can accommodate a slightly long case. You may want to trim one to see if it solves your problem before proceeding with bumping the shoulders.

Yes, you should be able to screw down the sizing die a bit at a time until you get to where you've bumped the shoulder back about .002". A Hornady Headspace Comparitor is a good tool to have.

 

[jjohnsonElknewbie]

It's possible, but unlikely, that you are experience trouble while chambering due to the case length being slightly over max length. Most chambers have enough throat that they can accommodate a slightly long case. You may want to trim one to see if it solves your problem before proceeding with bumping the shoulders.

Yes, you should be able to screw down the sizing die a bit at a time until you get to where you've bumped the shoulder back about .002". A Hornady Headspace Comparitor is a good tool to have.

Thank you for the advice. I screwed the sizing die 1/2 turn past "flush" on one of the sized .30-06 cases, and it still didn't reach the desired length or chamber easily. I have plenty of brass laying around to experiment another half turn, etc... I'm also going to get a comparator gauge or a Wilson case gauge

 

[SDHNTR]

I’m confused now. I thought we were talking about base to shoulder datum length since we were talking about bumping shoulders. Now you seem to be talking about overall case length? You can’t measure headspace (at shoulder datum) by measuring OAL of the case. You need a comparator.

 

[ckleeves]

It sounds like you’re trying to adjust case overall length with your die. You need to trim to shorten that dimension. You control the shoulder datum length with your die, coal with a trimmer. chances are if your camming over on a standard shell holder with your die then your probably already over sized.

The .003 guys talk about is shoulder datum off brass fired in that particular chamber, to determine trim length you can trim to “trim length” in your book (least accurate method but way better then jamming a long case into your chamber) use a borescope to see where your chamber is vs your brass or Sinclair makes some nice gauges for determining trim length.

 

[jjohnsonElknewbie]

I’m confused now. I thought we were talking about base to shoulder datum length since we were talking about bumping shoulders. Now you seem to be talking about overall case length? You can’t measure headspace (at shoulder datum) by measuring OAL of the case. You need a comparator.

Apologies, for the fired .25-06 cases all is good.

I ran into a new problem with the necked down .30-06 cases, and additional tools are needed that I didn’t know I would need.

Bit off a little more than I could chew resizing the .30-06 to .25 as a newb reloader.

 

[jjohnsonElknewbie]

It sounds like you’re trying to adjust case overall length with your die. You need to trim to shorten that dimension. You control the shoulder datum length with your die, coal with a trimmer. chances are if your camming over on a standard shell holder with your die then your probably already over sized.

Thank you so much for this and the other comments guys. So here are my next steps as I understand them, and please shoot holes in them if I'm off base.

For the resized "long" .30-06 cases:
1. Get a headspace case gage to verify the case shoulder is in the right position. If the case head is "above the maximum" ledge, I need to screw the die in a little until I get at or just under the maximum.
2. Once the shoulders are confirmed, trim any cases that won't chamber easily. 2.494 is SAMMI max and the FF .25-06 cases are all in this general length and chamber without effort. As result, it makes sense to trim the resized and shoulder-verified .30-06 cases to this length as well, correct?

For the FF .25-06 cases:
1. Get a universal decapping die and decap.
2. Since these already chamber easily, neck-size only and they should be ready for priming, charging, bullet seating, etc...

I watched a few different videos on the best way to "find the lands" and create a dummy round for COAL reference for the bullets I plan to shoot. My plan is to take a FF and neck-sized case, swab the case mouth with loctite, and push it into the chamber with the bolt (extractor removed). This should seat the bullet in the case at the ideal depth. On Ultimate reloader they recommended waiting up to 30 minutes or so to let the loctite set up. Next, pull the bolt and push the round out with a rod, and this should provide the ideal COAL for that specific bullet and a permanent reference cartridge.

Thoughts?

 

[ckleeves]

The first step is figuring out an accurate measurement of what your particular chamber measures from base to the shoulder datum. If it’s already been fired once in that particular chamber then pick a short piece that’s under trim max, measure to the shoulder datum and write that number down, neck size it (or use your FL die and don’t touch the shoulder) and fire it again. If it doesn’t grow or only grows by 1-2 thou then your probably there as far as the brass completely expanding to that particular chamber.

It’s really important to have accurate number for shoulder bump and not over size your brass, I have seen case head separations in as little as 3 firings from guys camming over a FL die on a standard shell holder and pushing shoulders back 10-12 thou every time they sized.

lots of different thoughts on trimming, IMO it’s good to know your actual trim length in your chamber so your not trimming to short but you can also pick a middle of the road number between min and max and trim to that, or find your shortest piece of brass and trim everything else to match.

It depends on what type of trimmer you’re using, some base off the shoulder so you need either fired cases that are completely formed or good consistent shoulder bump to end up with consistent trim length. Others base off the case overall length so they are cutting pretty much the same no matter where the shoulder is at when they are trimmed.

Your plan sounds pretty good, you just need some hard numbers on your chamber before going to crazy.

 

[49ereric]

I’ve never bought or used a headspace gauge or any chamber gauges.
my M1917 06 has a generous chamber common with military rifles.
I’ve let the brass grow and it still chambers in the M1917 but bolt won’t close in my savage 06.
you could use a 9mm case on top of the 06 case and get datum measurements.