Too Hot to Handle

by Bob Londrigan, published in Front Sight Magazine, November 2006

When your game is on, you’re hot.  When you’re shooting your gun like the dickens, it too gets hot.  But have you ever considered that it (your gun that is) may get too hot?  Your gun is very similar to a combustion engine as far as heat and friction are concerned. A bullet moving down the barrel is analogous to a piston moving in the engine block. To make matters even worse, a bullet is a tighter fit in the barrel and it is not lubed like the piston.   In the same way that heat and friction can shorten the life of a car’s engine, they will also shorten the effective life of your gun. So the question becomes, what heat levels are acceptable and what you can do to control heat in order to minimize wear and tear on your gun?

Unfortunately there is no definitive answer as there is no hard and fast data to work from.  The type of damage caused by heat, especially to the barrel, is cumulative over a long period of time.  I did some experimentation to determine what the typical operating temperatures are for a pistol subjected to the stresses of a heavy-duty IPSC type practice session. I also wanted to see if heat levels could be high enough to cause damage in the short term.  I was specifically worried about high temperatures changing the heat treatment of the barrel which could cause a permanent change in the hardness of the barrel. 

To get more information on this I called Irv Stone at Bar-Sto barrels to ask about temperature levels and to find out if he thought excessive heat could cause permanent damage. He told me of situations where he needed to heat barrels to cherry red in order to remove the compensators.  He later shot the barrels to see if there was any degradation in performance and to see if the barrels wore quicker.  He did not find any difference in performance.  He feels that heating your barrel up to about 500 degrees (the point at which it discolors) will not cause any short-term damage. 

However, Irv and I both agree that while this temperature may be OK short term, it will definitely accelerate wear on your barrel in the long term.  You must also consider that when you heat up your gun, its various components will heat at different rates.  The rate of heating will vary based on a part’s proximity to the heat source, the material of which it is made, and its thickness.  As the parts heat up they swell, and they will all swell at different rates.  So once your gun gets really hot, your nice tight fit may now be too tight.  A little of this swelling is a good thing because it allows your parts to rub and break in. However, if you heat the parts excessively you will excessively wear its parts.  And when the gun cools off, it will be just a little looser every time.

So how do you tell how hot your gun is getting?  I did some experiments to see what happens physically as your gun gets hotter.  I began by heating barrels to see what would happen at certain temperatures.  I found that at 500° F, permanent discoloration of the barrel occurred. This gives me a rough idea of how to tell how hot a barrel has been.  I have seen quite a few guns exhibit this discoloration. 

Overheated and discolored barrel

I also found several other benchmarks that can be used to tell how hot a gun is (even if you aren’t measuring its temp).  At around 140 degrees, anything metal on the gun was too hot to touch. At about 200 degrees, the FP10 oil on the barrel started to smoke. When the limited gun in my experiment got to a little over 200 degrees, the fiber optic rod showed no evidence of starting to melt.  I have seen guns with melted fiber optic rod, so those guns had to have been heated to well over 200 degrees.  The loctite that I use to fasten comps to the barrel is rated at 450 degrees.  At that temperature, it starts to break loose.  You can smell it (a kind of sweet resinous order), and it starts to smoke.  Heat also starts to migrate further back on the gun as time goes by.  I have had to stop practicing when the beavertail became too hot to touch. These benchmarks will let you know approximately how hot your gun is getting.

I also did a little experimentation to get a feel for what temperatures occur during a practice session and what maximum temperature you can attain in order to reduce wear and tear on the gun to a reasonable level.  First, I fired 100 rounds of major power factor ammo in a 38 super compensated gun, 20 rounds at a time, pausing just long enough between mags to take the temperature at the front of the barrel.  Following are the results:

# Rounds Shot

Temperature of Gun

0

70

20

109

40

133

60

180

80

196

100

229

I then let the gun cool off at room temperature and recorded the following readings.  The purpose of this was to simulate the pasting of targets and/or letting someone else shoot.

Time elapsed (minutes)

Temperature of Gun

1

187

2

160

3

155

4

142

5

135

10

99

15

90

I repeated the test, only this time I used one magazine and reloaded that magazine each time (adding time between shooting each string). Results were as follows:

# Rounds Shot

Temperature of Gun

0

70

20

110

40

130

60

160

80

173

100

185

I again repeated the test, but before I started I put the gun in an ice chest at 32 degrees for five minutes (starting temperature before going in the ice chest 185 degrees). After five minutes in the ice chest, the temperature of the gun was 112 degrees.  The results follow:

# Rounds Shot

Temperature of Gun

0

112

20

157

40

169

60

173

80

185

100

196

I think I could have continued at this pace, and the max temperature would have remained around 200 degrees. One thing to remember is that I did the test at 70 degrees.  If it had been a summer day at about 100 degrees, the results would be different (the temps would have been much higher).

I performed the first test with a 40 caliber limited gun just to make sure there were no major differences.  The temperatures overall were a little cooler but not so much as to make a major difference. Results were as follows:

# Rounds Shot

Temperature of Gun

0

70

20

109

40

149

60

169

80

196

100

208

So what does all this mean to you… the shooter who wants to maintain your gun in top condition? I think keeping your gun at 200 degrees or less (similar to your car engine) is a good baseline for minimizing long term wear on your gun. In order to achieve that, here are some suggestions:

If you follow these guidelines you should be enjoying your gun for many years to come, instead of spending time and money replacing its parts.

  1911 parts at Brazos Custom