Quick way to measure temperature of round for chrono assessment

[Clint007]

Would those IR thermometers be a good way to measure the temp of rounds before chrono-ing?   For my thermometer, at 8 inches the manual suggests the target should be at least 1 inch in size, so I plan to pour a bunch of rounds into a styrofoam cup so the thermometer only 'sees' the rounds (not any background item). Some will have been kept (for many hours to ensure equilibrium) at 40 degrees, some at 70, and some around 100 degrees.  Chrono those quickly.   Then see the temp influence on velocity.  I've had some annoying variations recently and wonder if it's temp (being summer in Phoenix)....my reloading room is 74, my car is at 110 during the day, and the mornings at some matches in CO and such in the fall can be 40-50s.....plus I'm just really curious about this with Titegroup, N320, HP38, etc.

C

[Bossgobbler]

I have shot from 28* - 98* with my N320 loads I have not seen that much of a change in PF. If you run your loads on the low side it could be a problem. When I do my chrono testing I am looking for about 130 PF -132 PF

[Wobbly]

Would those IR thermometers be a good way to measure the temp of rounds before chrono-ing? 

I've used those IR thermometers in several industries now, and although they can be handy, I don't believe that's what you need. They work by reflected light, and so the quality of the surface reflecting the light has a great deal to do with the accuracy of the temp reading.

In your instance, all your brass would need to be tumbled to the same shine factor. And if some cartridge cases were matte finish and some slick.... then that would also have a bearing.

No, if it's really a concern then I think the easy way is the best way for you. Buy a cheap thermal "cooler" (aka ice chest) and fit it with a thermometer. Pile all your ammo in there before you leave the house (maybe the night before). The individual rounds will start to change temp when you load your mags at the shoot, but the powder's temp probably won't change more than a few degrees in either direction before being shot.


Just my 2 cents 

[Clint007]

I've used those IR thermometers in several industries now, and although they can be handy, I don't believe that's what you need. They work by reflected light, and so the quality of the surface reflecting the light has a great deal to do with the accuracy of the temp reading.

In your instance, all your brass would need to be tumbled to the same shine factor. And if some cartridge cases were matte finish and some slick.... then that would also have a bearing.

No, if it's really a concern then I think the easy way is the best way for you. Buy a cheap thermal "cooler" (aka ice chest) and fit it with a thermometer. Pile all your ammo in there before you leave the house (maybe the night before). The individual rounds will start to change temp when you load your mags at the shoot, but the powder's temp probably won't change more than a few degrees in either direction before being shot.


Just my 2 cents 

Very good, thank you

C

[M1A4ME]

A white pipe will read a different surface temperature and than a stainless steel pipe which will read a different surface temperature than a galvanized steel pipe which will read a different temperature than a rusty steel pipe - even if all the pipes are exactly the same surface temperature.

A good IR unit is adjustable for (darn, word slipped away on me, as things do these days).  You have to do some preliminary work to measure surfaces with a contact thermometer, the read with the IR unit, then make an adjustment to the IR unit to get it to read the correct temperature and then record you settings so when you read that surface again you can make the correct adjustment to your IR temp. gauge.

I used to cheat.  I carried a can of flat black spray paint around with me and I'd make myself a black circle on the pipes I wanted to routinely measure the temperature of.  Every so often I'd hit the same black spot with another quick coat of fresh paint to correct for the fading, the dust, the bird poop, etc.  AHH!!!  I think it (the word) is emmisivity.   Different surfaces (textures/colors) emit temperature differently, affecting your fancy high dollar IR temp. ga. readings.

The scientific guys would get all upset at my numbers/figures/calculations, especially when I'd tell them whether the temperature was really 280F or actually 260F, the issue is that normally it was 30F lower so therefore something was affecting my process which was affecting the product - whether they could test for a difference or not, it was there.  Scientific guys and practical guys don't always work well together.

[1SOW]

Test your chrono results "using 10 or more rounds each test from the same batch of loads" in the summer heat, winter cold and maybe one temp in between the two extremes.  Like Bossgobbler said,  I haven't seen a significant change using n320.  Other powders may vary .

  Might be an interesting test with winter coming up.

[newageroman]

my amp meter came with a thermo testing leads, I wonder if that would be any better/help.
Its hard to imagine that anything could be better than chilling with a cooler and old style thermometer though. I read a recent article on rifle powder tests with regards to temperature and they vacuum sealed bags of 5 or 10 rounds, kept them in the cooler and gently warmed them up with containers of water before shooting.

Another thing to consider if you do use the IR gun is just to take the temperature of the gun as it heats up. That might be more repeatable/comparable figure.

[Clint007]

But it?s primarily the temp of the POWDER that drives this variation, right?

I am now just going to have two small coolers, one with ice packs and one without, in my car for 4-6 hours, just before I shoot them. With thermometers in the cooler measuring air temperature. While it won?t necessarily be super accurate on the true powder temp, the delta-T [change in temperature] should demonstrate a difference if there is one.....


[Mods added clarity]

[Wobbly]

But it?s primarily the temp of the POWDER that drives this variation, right?

If you truly want to know what effect the change in temp has on the powder, then 'Yes' "cold soaking" one mag of ammo to 40?F, while you allow another to reach a high ambient (of say) 110?F is the most expedient way to proceed.

The idea of stretching the test out over 6 months has several flaws...
? Some variations may creep in due to the effect of temperature on the chrono (or other test items)
? The exact same chrono may not be at the Club when you go back in 6 mos, so gaining the exact same "base line" would be impossible
? Notes or other necessary information may be lost in the intervening time
? Painter might shoot one or both chronos 

You might not end up knowing the exact temperature difference, but then the real question was about changes in powder over wide temperature ranges, not what did the powder do at exactly xx?F ?

 

[Clint007]

Plan to do them both on the same test. I'll have two coolers one with ice, the other with  a couple of bricks as a temperature buffer. I'll put a sheet of styrofoam over the ice/brick, set the MTM box atop that. Let them stay that way for 6-8 hours in my car to equilibrate, then test them within 20 min using my LabRadar.

C

But it?s primarily the temp of the POWDER that drives this variation, right?

If you truly want to know what effect the change in temp has on the powder, then 'Yes' "cold soaking" one mag of ammo to 40?F, while you allow another to reach a high ambient (of say) 110?F is the most expedient way to proceed.

The idea of stretching the test out over 6 months has several flaws...
? Some variations may creep in due to the effect of temperature on the chrono (or other test items)
? The exact same chrono may not be at the Club when you go back in 6 mos, so gaining the exact same "base line" would be impossible
? Notes or other necessary information may be lost in the intervening time
? Painter might shoot one or both chronos 

You might not end up knowing the exact temperature difference, but then the real question was about changes in powder over wide temperature ranges, not what did the powder do at exactly xx?F ?