anybody ever measured sizing die temperature?

"...not using lube on the cases..." Unless you have carbide dies, sooner or later they'll get stuck. Regardless of the source.
There isn't enough heat generated to matter.

Very interesting question. I wonder how much heat would be needed to change the diameter of the die?

Rather than grabbing a torch and heading down to the basement, I'll check around the electronic digital communications array tonight for the type of steel Hornady uses for thier sizing dies. I will then find the thermal expansion rate of said steel.

I doubt your thoughts were of them sticking. Were they more along the lines that the die may expand and cause sizing variation, resulting in chambering or setback problems?

I don't know about heat but I learned to reload in my neighbors shed in the winter and it got pretty cold sometimes. Both of us came up with some pretty tight groups using cold dies and nothing changed during the summer months.

Walkalong said:

Never really noticed, I do runs up to 500 at a time.

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Neither have I. I don't think I ever touched the die itself to know if it's hot.

taliv said:

for those with high volume progressive presses, have you ever measured the temp on your sizing die? how hot does it get?

i tend to load in small batches. i.e. load 100-200 rounds and then head to the range. so during the 3-6 minutes that takes, my die gets warm to the touch, while all the other dies remain a cool ambient temp. i'm just wondering if those of you who load 1000 rounds at a sitting or something have ever needed to manage the heat.

fwiw, i'm not using lube on the cases. we're talking 9mm range brass.

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I have noticed brass becoming warmer as one resizes.
FWIW, I do not think temperature of the die is going to make enough of difference that one would notice, whether by measurement or performance of your load. It may be measured, but the end result would be negligible IMO. Not a physicist, just going on experience....YMMV!

Walkalong said:

Never really noticed, I do runs up to 500 at a time.

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Same here.

I resize and neck expand on the progressive by itself. Since things are simple, no powder charge or bullet seating, rates get up to 1000-1200 cases per hour. Frequently, I pull the sizing die immediately after I've completed the last case and I cannot say I have felt the die being warmer.

But, my fingers are not calibrated either.

In theory, the friction involved with dry resizing even with carbide dies should add some BTUs to the die.

9mm with its tapered walls may generate more friction as more of the die may be in play sizing the case over a greater length inside the die than with a conventional straight walled carbide sizing die. (Hope that made sense).

Well, I didn't find anything about Hornady's sizing dies, but I imagine they are not some super secret formulation.
A file from Bal Seal indicates the coefficients for many types of steel, aluminum and other alloys. As well as plastics.
If I used the equation correctly, between the temperatures of freezing and boiling water (at atmospheric pressures), a seven eighths inch long piece of cromolly steel expands about six and one eighth, one millionths of an inch. Fourty one fourty tool steel expands less, at eleven ten millionths. Of course, only if I understand the formula correctly and I didn't stay at at the Holiday Inn Express last night.

However a sizing die is not seven eighths soild, and the circumference is greater. But how that effects the expansion I am uncertain of. I suspect that heating the die with a torch will cause a size variation from expansion. I will be completely unable to measure it though.

And I don't want to burn the paint off my press either!

I have done up to 3,000 (not a typo) pistol cases in one go on several occasions with no lube (9mm, .38 Special, and .45 ACP come to mind). Never noticed any excess heat or brass that wasn't in spec and usable. I did notice that the next few days I was extremely sore though!

Are any of you loading at the same pace as the OP? That is, 2000 rounds per hour?

higgite said:

Are any of you loading at the same pace as the OP? That is, 2000 rounds per hour?

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He asked about people who do 1,000 rounds in a sitting, but said he does 100 to 200. Unless you are running a Camdex or other fully automated machine 2,000 per hour is a tall order for manual operation. I can fully load up around 400 to 500 rounds per hour on a Dillon 550 and that's really flying. More typically it's far less and that is IMO fairly representative of any progressive platform when you count in restocking primers, cases and bullets.

The 1050 may well skew the numbers a bit, especially with one of those automated setups, but I would think even at that speed if there was an issue, the end user would notice a lot of failures to chamber, etc IF it was that much of an issue. Since there are several outfits that do this very practice with the intent to sell ammo, I would think at some point there would be issues at the customer end. Heck maybe there are!

I had honestly never given it a thought before this thread, but I would be surprised if you could effectively run the press fast enough - that is, still turn out a fully sized case - to make the die change enough to put those cases out of spec.

Not that you shouldn't ask. It's as good a question as any IMO.

I'm no scientist, but being that the die is steel, I would think it would take quite a bit to change to the dimensions, especially with how thick most dies seem to be.

The thicker the steel piece, the greater the expansion. Going from room ambient temperature to just over human body temperature is much less than the one hundred eighty degree change in the example. Both however are very small, very close to zero infact. For my ways and means I will treat it as zero. One less thing to think about!

I use a SS or turret press and size/decap 500 to 2K in a sitting but never even had this on my radar. With an automated press it might be a factor but surely not for me. For the sake of it next time I process a batch I will feel my die and see if there is any difference at all. If so I will comment here.

Never found any need to manage the heat, 100 rounds in 4 minutes then stop for some time to refill before starting. Even my computer controlled machine that loads 1000 rounds in 52 minutes without stopping has never needed a cool down or for that matter sizing and depriming them at over 4000/rounds per hour and that’s as fast as any of my operations run.



The process for me is pretty low energy though, I do lube.

I haven’t seen any liquid cooled (except for lubricants) or air conditioned manufacturing equipment even for case forming and that would be a much more likely place to need it as a lot more energy is needed for the process and it occurs at a much higher rate than 33 times a minute. For rifle case manufacturing there is insufficient heat and they actually have to add more to be able to form them (annealing).


Or about a minute into this one.

jmorris said:

Never found any need to manage the heat, 100 rounds in 4 minutes then stop for some time to refill before starting. Even my computer controlled machine that loads 1000 rounds in 52 minutes without stopping has never needed a cool down or for that matter sizing and depriming them at over 4000/rounds per hour and that’s as fast as any of my operations run.



The process for me is pretty low energy though, I do lube.

I haven’t seen any liquid cooled (except for lubricants) or air conditioned manufacturing equipment even for case forming and that would be a much more likely place to need it as a lot more energy is needed for the process and it occurs at a much higher rate than 33 times a minute. For rifle case manufacturing there is insufficient heat and they actually have to add more to be able to form them (annealing).


Or about a minute into this one.

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That's pretty fast right there. I'd say that would pretty well make it a non-issue.