Gen5 Glock heat issues

[Clusterfrack]

The open port seems like a likely explanation. The thermal effect of the DLC finish is an interesting idea from a physics perspective, but I doubt there is a significant difference. See Kirchhoff’s law that predicts thermal energy absorption and emission due to radiation.
https://en.m.wikipedia.org/wiki/Kirc...rmal_radiation

At only 150 deg F, emission is largely in the IR, and most objects are nearly black bodies at that wavelength. However, polished teapots retain heat better than black rough ones because a mirror finish’s emissivity is lower, so there could be something to your idea.

[Eyesquared]

If you used an infrared thermometer to take those temperatures, a difference in emissivity between the two slide finishes could be introducing error into your measurements. They could both be the same temperature but due to typical household IR thermometers having fixed emissivities, you would get different readings. I don't have a gen 5 glock so I can't say one way or the other whether it could be hotter.

[farscott]

Nor am I, but the Gen 4 G34 also has the big open port on the slide to dissipate heat and in this case, the G34 is not wearing an optic, like the G17 is, that is also capable of retaining heat.

My understanding of the reason for the slide window on the G34 is weight reduction, not thermal transfer. The G17 slide weighs between 12.6 and 12.7 ounces. The G17L slide weighs 13.2 ounces. The G34 slide weighs between 13.1 and 13.3 ounces. Assuming the steel is the same (may not be), I would expect the G34 to be cooler than the G17. But this is not simple as the G34 has a longer, heavier barrel, so the bullet is in the bore longer and has more metal to heat and more surface area to transfer heat. As such, I am loathe to draw any conclusions without a thermal simulation and a lot of controlled, instrumented experimentation.

[1Rangemaster]

I appreciate the effort, but without identical units-17 to 17, 34 to 34, I can’t see a valid comparison. It might be interesting for a comparison between Gens 3,4 and 5. That would be Tenifer, nitration and nDLC finishes if I’m recalling my Armorer course correctly. It seems one would have to figure out how to measure the temp inside the battery compartment.
I understand the appeal: how long will a critical system (sight) function? Mine is about two months on with the issued battery. I plan to change it on July 4th, and see if it goes to New Years Day. On mine, I go up one intensity level; certainly all eyes are different, and it’s also situational. If I’m out in AZ in that sun, that will be different than woods in the SE.
Given the low expense of the CR1225 battery, I could make an argument for change every 3 months in “duty” use. Heck, that would at least get officers to handle the weapon on that schedule. Sadly, my observation is that many do not.
No news to anyone here, but I am committed to this sight. Time will tell.

[JTQ]

My understanding of the reason for the slide window on the G34 is weight reduction, not thermal transfer.

I agree with you 100%.

I didn't say it was designed to dissipate heat, but having the opening does seem to me as if it would allow heat to escape better than a closed slide.

[farscott]

I agree with you 100%.

I didn't say it was designed to dissipate heat, but having the opening does seem to me as if it would allow heat to escape better than a closed slide.

I am not sure as the metal slide should be a much better heat sink than the air exposed by the slide opening. The air between the barrel and the slide (and between the barrel and frame) is an insulator as it resists the transfer of heat from the surface of the barrel to the top inner surface of the slide (or frame). I did look at the thermal conductivity of some of the Ionbond/DLC variants, and some have high thermal conductivity and some have relatively low thermal conductivity. DLC is a pretty broad family of finishes with vastly different properties, depending upon the needs of the application, So it is possible the surface treatment plays a role in the observed temperature differences.

[Clusterfrack]

Thermal conductivity is limiting if the heat transfer mechanism is conduction. I’m betting that under most conditions, the primary mechanism is radiation, so it is the emissivity that is the key parameter. My understanding is that conductivity and emissivity are not always congruent in metals.

[MistWolf]

The important thing to look at are the barrels. The thicker the barrel, the more heat it takes to reach the same temperature. If the Gen 4 Glock has a thinner barrel, gonna get hotter with the same rate of fire.

The heat will soak into the slide, but inside the barrel is where the heat is generated.

[TCinVA]

If you used an infrared thermometer to take those temperatures, a difference in emissivity between the two slide finishes could be introducing error into your measurements. They could both be the same temperature but due to typical household IR thermometers having fixed emissivities, you would get different readings. I don't have a gen 5 glock so I can't say one way or the other whether it could be hotter.

There was most certainly a significant difference in temperature to the touch.

Keep in mind, fellas, I've been shooting handguns seriously for 20 years. I've done multiple 5 day classes where we fired 1,000 rounds per day with a number of different handguns. I've owned Glocks off and on more than 20 years.

The heat in the Gen5 is significantly more than what I have experienced with any other handgun save for the P7 series.

Tom Givens has put a round or two through Glocks over the years and as a sanity check I had him touch my slide after a very small round count and he, too, was surprised at how hot the thing was getting.

Whether the IR thermometer is giving an exact temperature reading that is accurate to a hundredth of a degree I can't say. What I can say is that they are used pretty extensively to measure the surface temperature of pans used for cooking and they reputedly work pretty good on metal surfaces that are not highly reflective...like the slide of a Glock pistol. I'm looking for a general trend and so if the measurements are off by a few percentage points from what some other measuring device would show that's not really impacting the result. Even if it was 10 degrees off, it's still putting some numerical quantification to an observed phenomenon that has been verified by multiple people with my particular sample: It gets a lot hotter than other guns. And it does so more quickly.

The impulse to put a thermometer to the gun came after spending a day with the muzzle of the fucking thing burning my crotch. I've shot a lot of high round count days with a lot of different handguns in the last couple of decades and I'm telling you this is either noticeably different or I'm suffering the weirdest form of neuropathy known to man.

Something else worthy of note is that the barrel of the Gen5 G17 read a temperature that was significantly lower than the slide, which I thought was crazy...but it was also cooler to the touch.

I don't know for sure what's causing it.

We do know for sure that Glock has made several changes to the Gen5 guns including rifling in the barrel and the finish on the slides. It's possible the metallurgy of the slides has changed. It's possible that the contact between the barrel and slides on the Gen5 guns has changed.

Whatever the cause, the thing gets fucking hot. I'm not the only person who has observed this, but as far as I know I'm the only one who has attempted to put some data to it. The numbers are easier to grapple with than me reporting that having fired both guns back to back the Gen5 gun is hot as balls, hot enough to feel like it's burning you through a holster and the Gen4 gun isn't.

Like I mentioned earlier, I'm going to try and do a simple measurement of a Gen3 G17 before and after 6 magazines fired as rapidly as possible and the Gen5 G17. I doubt it will make a significant difference in the observed results because I've spent a minute or two shooting the Gen3 G17 and it's never gotten as hot as the Gen5 gun. It will certainly heat up, but not as hot as the Gen5 gun will get. I will also let the guns sit in the open air for the same length of time to see which one cools down faster.

I cannot construct a truly scientifically valid test because, among other things, I don't have a statistically significant number of guns to perform a test on.

[psalms144.1]

TC - thanks for the info, I haven't noticed a difference in my Gen5s, but, sadly, I've RARELY had the chance to get them really worked out on a range - a couple hundred rounds in a day is a "heavy" shooting day for me now, due to ammo and range constraints. I appreciate your efforts, even if the thread reads like this to me:

TC - "Gen5s are hot as balls"
A bunch of other people - "Yeah, like, science, and blahblah, blah blah blah, science"
TC - "Fucking thing burns my fucking balls in the holster after shooting it a bit"

Seriously, I will be interested in your admittedly non-scientific results shooting a 3rd Gen G17 side-by-side with a Gen5 G17. For the aforementioned sciency-fuckers, please note that there was never a "Gen3" or earlier Glock pistol, they're properly referred to as 1st, 2nd, and 3rd Generation guns. Only with the Gen4 and later did Glock attempt to become hipster in their labeling.