Brass growth on resizing once-fired

[James87adams]

I'm newish to reloading in a progressive press. I've loaded a little in a single stage, where I just screwed the die down all the way, deprimed, resized, trimmed, primed by hand, etc. I upgraded to a dillon 750xl, and getting into reloading a lot more and have a ton of questions.

I'm primarily loading 223 on this setup, and my sizing die is screwed in all the way to a slight cam-over. I want to trim before I size, that way I can complete all of my actions on the press in one cycle. Clean, trim, lube, then get into the press to deprime, size, prime, powder, and load bullet.

I have been trimming my oversized brass to 1.750, and then when I resize I noticed it can grow .005"-.007". I'm not too worried about the OAL as I'm just shooting in my ARs, but I'm wondering if I need to sand down the bottom of my die so I can ensure I'm actually bumping the shoulder back a couple thousandths. I've got RCBS dies (think the one I've got in my press is the x-sizer).

Am I overthinking this? Or am I missing something? I know it's still within the case oal, but if I'm going through this process, I may as well try and do it to load in the most consistent way possible.

 

[FLIGHT762]

This is why you trim after F/L sizing. That's the only way to trim to get a consistent length. Before F/L sizing, your case mouths can be out of round, bent etc. giving inconsistent lengths even if you trim that extra .005"-.007". What tool are you using to trim? You can trim before F/L sizing if you are using a Dillon trimmer since it has a die that sizes the cases as they go into the trimmer.

You said you set your F/L die by screwing it all the way down to a slight cam over. How do you know you're not over or under bumping the shoulders on your brass. Are you just guessing? How are you measuring shoulder bump?

 

[James87adams]

I'm using a forster case trimmer.

I set the depth of the die by checking a once fired case in a gage, trimming to 1.750, sizing, and then checking in the case gage again. If I dont have the die set deep enough then the case extends above the case gage. I dont think this is a great way to figure out die setting since I'm only going to be bumping the shoulder back a couple thou at a time when I size, and it seems to be pretty inconsistent, as in, if I resize a handful of brass of different lengths, some will pass and some wont via the gage.

So basically I know I'm doing something wrong in terms of sizing but I'm not sure what I need to be doing to avoid breaking out of the progressive press in the middle of the cycle.

 

[Supersubes]

If im understanding you correctly, you're confusing two different results from the sizing operation. What case gauge are you talking about, youre vague about this? In the case of a wilson case gauge, its showing you both headspace and overall length tolerances. So which end of the case is sticking out, the case head, or the neck?

Cases will grow in overall length when full length sized, no biggie, deal with it as needed.

You didnt mention headspace though, which is half the purpose of a full length die. To push the case shoulder back to a proper location. “Proper” depends on your goals.

 

[James87adams]

Sorry, I'm using a Dillon headspace gage. Theres a notch showing the min/max length from base to shoulder.

The base sometimes extends above the notch occasionally, and almost randomly, by a few thousandths. The mouth never extends past the gage. So I am pretty sure this means that my shoulder to base length is set too high and I need to run my die down lower to set back the shoulder so that the case fits deeper into the gage?

 

[FLIGHT762]

The one caveat on using a drop in gauge like the Dillon is you can occasionally get a bent case rim and the rim will not go into the gauge, giving you a false reading, even though the case has been properly sized.

 

[James87adams]

I dont think I'm getting bent rims, just occasionally the rims are a few thou proud from the surface and I'm wondering if it is a result of my die set poorly.

 

[rustyinbend]

I've found (for me at least) the only way to make an accurate trim decision, is (a) after FL sizing, and (b) with calipers to measure case overall length.

 

[remaction]

Brass grows in length when full length sizing. The brass has to go somewhere when squeezed. Its confined on all sides except the top when full length sizing so some of the excess brass gets squeezed upward, it doesn't all simply compress to the inside of the case.

It sounds like you are thinking that if you set the shoulder back more, then your growth in length will be negated. Forget that notion. 1) once again, some of that squeezed brass will flow upward and 2) you will likely be creating excessive headspace and may see case ruptures near the case head down the road from a repeated firing/excessive resizing process.

Get a pair of calipers and a Hornady Lock-n-load headspace comparator. Using the correct insert in the comparator, measure your length from mid-shoulder to the base on a fired case. Next, run the case through the sizing die and once again check the length. Is it .001" or .002" shorter? I set my sizing to be about .001" on bolt guns to minimize the growth/excessive resizing to extend the brass life and also have a case that fits like a glove in the chamber.

Lastly, with tapered cases, you will have to trim after a few reloadings. This seems to depend on the case size and the case taper. My brothers .25-06 cases need regular trimming. Case length growth is one reason I have not made the jump to a progressive press for my rifle cartridges. Just a personal choice, not right or wrong.

 

[rustyinbend]

Brass grows in length when full length sizing. The brass has to go somewhere when squeezed. Its confined on all sides except the top when full length sizing so some of the excess brass gets squeezed upward, it doesn't all simply compress to the inside of the case.

It sounds like you are thinking that if you set the shoulder back more, then your growth in length will be negated. Forget that notion. 1) once again, some of that squeezed brass will flow upward and 2) you will likely be creating excessive headspace and may see case ruptures near the case head down the road from a repeated firing/excessive resizing process.

Get a pair of calipers and a Hornady Lock-n-load headspace comparator. Using the correct insert in the comparator, measure your length from mid-shoulder to the base on a fired case. Next, run the case through the sizing die and once again check the length. Is it .001" or .002" shorter? I set my sizing to be about .001" on bolt guns to minimize the growth/excessive resizing to extend the brass life and also have a case that fits like a glove in the chamber.

Lastly, with tapered cases, you will have to trim after a few reloadings. This seems to depend on the case size and the case taper. My brothers .25-06 cases need regular trimming. Case length growth is one reason I have not made the jump to a progressive press for my rifle cartridges. Just a personal choice, not right or wrong.

Great perspective ... agree 100%. Only added suggestion would be to anneal before re-sizing. Getting my AMP and annealing everything before sizing, has made noticeable improvements in my accuracy.

 

[remaction]

One step at a time. Just trying to get him up and running right now. Then he can start spending more money down the road on all the enhancements.

 

[rustyinbend]

One step at a time. Just trying to get him up and running right now. Then he can start spending more money down the road on all the enhancements.

My strategy was to spend big money early and often, and then sell unneeded stuff "used" at a big loss. The lessons learned were "priceless".

 

[James87adams]

Haha yeah, this is already a money pit.
I'm only reloading the 223 for plinking.

I get the concept of growth. I think yall are right that im just overthinking it. I read through my x-sizer die instructions again, it says to trim to .020 below max, for the first sizing only, and then basically run the mandrel down on a correctly sized case, and then your .020 undersized cases should butt up against the mandrel on the following sizing and stop/limit growth close to there.

What's really messing me up is that I've got about 2k twice fired brass, and they range from 1.730-1.765 in length, all were fired in the same AR for their last firing. So I basically separated them into undersized brass (under 1.750) and oversized, which I trimmed to be consistent, sized, and then reloaded.

I suppose I need to take the oversized to 1.740, set my x sizer die correctly per instructions, and then trim everything to 1.740 and go from there. I know the x sizer doesnt get great reviews, but it's what I've got.

I was getting lots of bulged necks from my seating die, so I backed the crimp off and haven't had any since, but I'm kind of worried the x sizer will bulge necks if the case lengths get close to the mandrel.

 

[James87adams]

Basically it sounds like I probably have all my dies set poorly. My big issue was I was thinking my sizing die body was not low enough due to inconsistent results with a chamber gage, but that's probably also due to inconsistent cade lengths.

So I'll probably run the mandrel down on the sizer, and then leave the crimp off on the seater like it is now. Should result a bit better with more consistent case lengths

 

[James87adams]

And my other big thing I dont understand-
How far I screw in my die dictates my shoulder bump right? And if I have my shoulder set to bump back slightly, it will only bump back a couple thousandths each time I size my brass right? So how do I figure out if my sizing die is deep enough?

 

[remaction]

And my other big thing I dont understand-
How far I screw in my die dictates my shoulder bump right? And if I have my shoulder set to bump back slightly, it will only bump back a couple thousandths each time I size my brass right? So how do I figure out if my sizing die is deep enough?

Re-read my post regarding the Hornady comparator. Adjust in or out depending on the caliper measurements from before and after sizing. Use a fresh case for each time you measure (i.e. do not keep resizing the same case to measure your shoulder bump). Invest in one of those comparators, I use them a lot for headspace and also seating depth measurements with the appropriate inserts.

 

[remaction]

Also, there is another way if you are reloading for a bolt gun and can remove your firing pin assembly. Are you loading for an AR? If so, I would recommend the comparator?

 

[spife7980]

And my other big thing I dont understand-
How far I screw in my die dictates my shoulder bump right? And if I have my shoulder set to bump back slightly, it will only bump back a couple thousandths each time I size my brass right? So how do I figure out if my sizing die is deep enough?

The comparator like was mentioned above.
How do you measure consistently on a coned surface? You use a datum, aka a hole that sits evenly down on the cone across a plane.

 

[James87adams]

I looked those up today. I suppose I'll have to get one!

 

[James87adams]

Ok so I picked up a comparator.

I'm trying to figure out what I need to do so I'm all over the place.

Most of the ammo I had loaded for loads dev/ladder was right at 1.625. A couple measured over by about 15 thousandths. I set those aside.

I measured a handful of once fired brass, two were 1.640 +/- .002 and the other five were 1.624 +/- .002. After resizing as i had the dies set, all sized 1.624-1.625, including the ones that were sitting at 1.623. (So I'm confused how a couple of my loaded rounds were 1.640, maybe I ran the press too fast or didnt dwell at the top, or maybe I messed with my dies.)

I measured my factory unfired FGMM 168 smk and they all came out to 1.6205 +/-.0003. This ammo fires under 1/2 moa in my rifle so I'd like to replicate it with the 169 smks I've got.

My brass is all hornady and FGMM once fired, with a few pmc match (I know, it was cheap). Most was fired through my savage that I'm working this load for, and I'm guessing that the few 1.640 were fired through a r700 that I used to have.

So, being that SAAMI above says min length to datum is 1.6272, it's interesting that all of the FGMM I measured were consistently 6.7 thousandths under.

So basically, if I'm doing this right, I want to make sure the length of my fired brass to get my chamber size (I'm guessing its 1.624) and I want to set my dies to set my shoulder back on those about .002?

I wonder if there is a small radius on the comparator tool that is a few thousandths and throwing all my measurements off?

Am I thinking about this right?

 

[James87adams]

And I know my original post was about 223. I'm loading both, but only plinking ammo for 223 at the moment and trying to work up a load correctly for the 308.

 

[6.5SH]

Ok so I picked up a comparator.

I'm trying to figure out what I need to do so I'm all over the place.

Most of the ammo I had loaded for loads dev/ladder was right at 1.625. A couple measured over by about 15 thousandths. I set those aside.

I measured a handful of once fired brass, two were 1.640 +/- .002 and the other five were 1.624 +/- .002. After resizing as i had the dies set, all sized 1.624-1.625, including the ones that were sitting at 1.623. (So I'm confused how a couple of my loaded rounds were 1.640, maybe I ran the press too fast or didnt dwell at the top, or maybe I messed with my dies.)

I measured my factory unfired FGMM 168 smk and they all came out to 1.6205 +/-.0003. This ammo fires under 1/2 moa in my rifle so I'd like to replicate it with the 169 smks I've got.

My brass is all hornady and FGMM once fired, with a few pmc match (I know, it was cheap). Most was fired through my savage that I'm working this load for, and I'm guessing that the few 1.640 were fired through a r700 that I used to have.

So, being that SAAMI above says min length to datum is 1.6272, it's interesting that all of the FGMM I measured were consistently 6.7 thousandths under.

So basically, if I'm doing this right, I want to make sure the length of my fired brass to get my chamber size (I'm guessing its 1.624) and I want to set my dies to set my shoulder back on those about .002?

I wonder if there is a small radius on the comparator tool that is a few thousandths and throwing all my measurements off?

Am I thinking about this right?

Some key concepts to keep in mind.

The first is right in the name of the tool, it is a "comparator". It is not going to provide the same measurement as your noted 1.6272".
Now let's say you HAVE a piece of brass that truly is 1.6272" from base to datum. Your caliper and comparator will give a valid measurement even if it is not the 1.6272" you were expecting. You would note this reference measurement (new brass, fired in a specific chamber etc.). Then "compare" it to other measurements you take with your resized brass etc. The numbers you get likely will not agree with someone else's using a different caliper and comparator. They are yours, for your reference. To keep my historical notes consistent I dedicate a caliper to the task and never move the barrel, just the inserts.

The other item is there is a "feel" that has to be developed to know when you have a good reading. You can measure slightly off axis and not notice unless you practice moving the brass and take a few measurements to know what is consistent. Hornady does make a larger base called an "Anvil" but IMO it is crap. It does not attach square nor stay that way. There is a vendor here on the PX that offers a different design that looks well made but I have not tried it yet.

 

[FLIGHT762]

So, being that SAAMI above says min length to datum is 1.6272, it's interesting that all of the FGMM I measured were consistently 6.7 thousandths under.

So basically, if I'm doing this right, I want to make sure the length of my fired brass to get my chamber size (I'm guessing its 1.624) and I want to set my dies to set my shoulder back on those about .002?

I wonder if there is a small radius on the comparator tool that is a few thousandths and throwing all my measurements off?

Am I thinking about this right?

You have a Comparator, not a SAAMI headspace gauge. It is NOT going to give you SAAMI measurements, get that out of your head. There is a radius on the comparator and that is one reason why you're not getting SAAMI measurements.

Your measurements off of your factory GMM is going to be a couple of thousandths below SAAMI minimum. Your measurement of the GMM @ 1.620"-21" give you that number.

If your fired cases are 1.624", you want to set your die to size @ 1.622". That's your numbers, go with them. Those numbers are about right.

Also, when you measure the datum line on fired cases, the cases need to be deprimed. Primer cratering can show false readings by about +.005".

You should not be getting any measurements of 1.640". That's way out of normal range. Something goofy with those cases.

 

[Kra961]

I'm newish to reloading in a progressive press. I've loaded a little in a single stage, where I just screwed the die down all the way, deprimed, resized, trimmed, primed by hand, etc. I upgraded to a dillon 750xl, and getting into reloading a lot more and have a ton of questions.

I'm primarily loading 223 on this setup, and my sizing die is screwed in all the way to a slight cam-over. I want to trim before I size, that way I can complete all of my actions on the press in one cycle. Clean, trim, lube, then get into the press to deprime, size, prime, powder, and load bullet.

I have been trimming my oversized brass to 1.750, and then when I resize I noticed it can grow .005"-.007". I'm not too worried about the OAL as I'm just shooting in my ARs, but I'm wondering if I need to sand down the bottom of my die so I can ensure I'm actually bumping the shoulder back a couple thousandths. I've got RCBS dies (think the one I've got in my press is the x-sizer).

Am I overthinking this? Or am I missing something? I know it's still within the case oal, but if I'm going through this process, I may as well try and do it to load in the most consistent way possible.

You really want to trim after sizing not before the brass stretch’s after fl sizing, if you swing it I use the rt1500 or some other trimmer mounted on the same head it makes the process a lot quicker.

 

[abn31c]

You really want to trim after sizing not before the brass stretch’s after fl sizing, if you swing it I use the rt1500 or some other trimmer mounted on the same head it makes the process a lot quicker.

It's a year old, he's prolly figured it out by now...

 

[Kra961]

View attachment 7815059
It's a year old, he's prolly figured it out by now...

Lol yup I would suspect so

 

[Steel head]

View attachment 7815059
It's a year old, he's prolly figured it out by now...

Kitty is wise, listen to kitty!

 

[James87adams]

Haha yeah. I got it figured out. There is a lot to the dillon presses, but I'm figuring it out.

I appreciate all of your help. I moved, and just got all set up again and now I just have a whole new mess of issues. I think that's just how it goes with reloading!

Pretty sure this time it's just really really really cheap 223 bullets that are out of round.