Gen5 Glock heat issues

[JodyH]

It was 103F under a white hot 3PM sun when I hit the range Monday, my 19X became uncomfortably hot AIWB in horsehide within 50 rounds.
Me and two other shooters were doing some 8 round drills from the holster on steel and the turnaround was quick enough that the 19X never cooled, it just kept getting hotter and hotter.
To finish out the day I'd shoot 17-20 rounds or so and then lock it open and pour ice cold water all over the slide and barrel before loading up and reholstering.
In all I shot 300 rounds in about 2 hours and went through 4 or 5 bottles of ice water.
High volume range sessions are a bitch withe the new finish.

[Tyrok]

First of all, I want to say that this thread has been a fascinating read, kudos to everyone providing such interesting information.

I'm not sure if Cerakote's new hi temp coating is available for purchase yet, but these guns sound like prime candidates for it.

https://www.youtube.com/watch?v=FzHJLf2kPqo&t=508s

Thoughts?

[JodyH]

Teaser....

Gens 2, 4 and 5 and a Flir E95

Attachment 41535

[WDR]

Teaser....

Gens 2, 4 and 5 and a Flir E95

Attachment 41535

Now we are getting somewhere...

[JodyH]

Very not surprising results.

First let's talk emissivity.
Definition cut/paste:

What Is Emissivity?
Emissivity is a measure of the efficiency in which a surface emits thermal energy. It is defined as the fraction of energy being emitted relative to that emitted by a thermally black surface (a black body). A black body is a material that is a perfect emitter of heat energy and has an emissivity value of 1. A material with an emissivity value of 0 would be considered a perfect thermal mirror.

For example, if an object had the potential to emit 100 units of energy but only emits 90 units in the real world, then that object would have an emissivity value of 0.90. In the real world, there are no perfect "black bodies" and very few perfect infrared mirrors so most objects have an emissivity between 0 and 1.

Some cut/paste on what emissivity does to heat transfer and surface temps (to save me some typing)

How Emissivity affects Heat Transfer and Surface Temperature

A reader writes:
"I know the higher the emissivity a surface has the greater its ability to absorb heat (IR), however, is a painted surface able to reject or shed heat better? An example would be does a painted engine run cooler than a unpainted metal engine or hotter or the same temp?"

If an object has a higher temperature than its environment, then increasing its emissivity will certainly lower its temperature. As an example, lets look at the motor in the illustration. It has a cover made of stainless steel and is very shiny. Let's assume its emissivity is 0.1. We have measured its steady state temperature at 150 F. The rate of heat generation of the motor has to be exactly balanced by the rate of heat loss from the motor. So, in this case for simplification, we will only consider convection and radiation. The numbers are shown in the illustration.
Attachment 41543
Now, if we painted the motor with flat paint, the heat transfer will change. We still have to get rid of the 63 Btu/hr being generated by the motor, but if we assume a new emissivity of 0.9, then the huge increase in the radiation loss will reduce the surface temperature to 118 F as shown.

(L to R) Gen2, Gen4, Gen5-19X
Apparent temperatures are wildly different, yet the slides are all within a degree or so of each other in reality.
Attachment 41540

(L to R) Gen2, Gen4, Gen5-19X
Spots 4, 5, 6 are on Scotch Super 88 electrical tape applied to the slides. Super 88 tape has a known emissivity of 0.95. Notice that all three slides are actually within 1 degree of each other (compare that to the uncorrected temperatures of spots 1, 2, 3).
Attachment 41541

After determining the emissivities of the three slides here's what I came up with.

Gen2 - 0.93
Gen4 - 0.62
Gen5/19X - 0.05

Gen2 is a pretty good emitter, pretty much as good as it gets in the real world.
Gen4 is a fair emitter, about like oxidized copper or hardwood.
Gen5/19X has a ridiculously low emissivity value on par with polished aluminum or polished copper.

All this to say... yes the Glock 19X is going to have a significantly higher surface temperature than a Gen2 or Gen4 for the same amount of energy input.
Science bitches.


Long term effect of high volume shooting is the polymer parts are going to get hotter faster as well with possibly detrimental effects.
The super low emissivity of the Gen5 coating makes me question whether Glock thought things through with this coating and if they did choose it on purpose... why?

[JodyH]

Next order of business is to shoot a lot and really heat things up.

[RJ]

@JodyH thank you for this assessment and evaluation.

That is some pretty conclusive data.

[JodyH]

One last thing I observed is that the Gen5 barrel has a high emissivity value.
Looks like the Gen5/19X might be the worst of both worlds when it comes to slide temperature.
Not only is the barrel radiating heat exceptionally well, the low emissivity slide is retaining that heat exceptionally well.
The flip-side is that if you lock the slide open where more of the barrel surface can radiate its heat off into space then it should shed its heat pretty fast.

[MRW]

That's good stuff. Thanks for the research. Does anyone know of there is something like an industry standard for this type of heat retention? It would be interesting to see what the data is for other pistols too. H&K, Sig, etc.

[spinmove_]

When I took CDR’s Tests and Standards class in July I ran it with a G19.4 in a JMCK IWB holster. The takedown lever on that thing got HOT on a 92F plus day during some high round count strings. It got legitimately uncomfortable to keep it holstered after a while. I can’t imagine what a Gen5 would feel like during a similar class.


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