Cooling handgun barrels during load testing

[barnfrog]

Posted a similar question in another forum but don't see any responses and I'm an impatient fellow.

When reading posts or articles about rifle load tests, one almost always sees notes about how long the barrel was allowed to cool between shots and groups. When reading about handgun load testing, there is rarely if ever any mention of letting the barrel cool. Does barrel temperature, and changes in that temperature between shots and groups, not affect group size and/or POI in handguns as much as it does in rifles?

 

[EricBu]

I have 3 rifles that I cool the barrels when doing load testing...because they are for long distance shooting, and barrel temp makes a pretty big difference. My Barrett 338 LM, my Savage 308 in an Oryx chassis, and my no name cheapie 22 inch AR 15. 2 reasons to cool it, one is that the groups change and POI change, which is annoying when working up a load, or when shooting 1/2 mile plus, and 2...the barrel heat (and if equipped, the suppressor heat) start causing a real mirage problem real quick. You can mitigate the mirage a bit with wraps. I will generally shoot 3 rounds with the 338, and 5 with the 308 and 223, then pull the suppressor, drop it in a cooler (not touching the ice, I wrap it in an oven mit), then hang wet rags on the barrel, move it off the line and set up my next gun or let the next guys in the group go while the can cools off.

 

[barnfrog]

I have 3 rifles that I cool the barrels when doing load testing...because they are for long distance shooting, and barrel temp makes a pretty big difference. My Barrett 338 LM, my Savage 308 in an Oryx chassis, and my no name cheapie 22 inch AR 15. 2 reasons to cool it, one is that the groups change and POI change, which is annoying when working up a load, or when shooting 1/2 mile plus, and 2...the barrel heat (and if equipped, the suppressor heat) start causing a real mirage problem real quick. You can mitigate the mirage a bit with wraps. I will generally shoot 3 rounds with the 338, and 5 with the 308 and 223, then pull the suppressor, drop it in a cooler (not touching the ice, I wrap it in an oven mit), then hang wet rags on the barrel, move it off the line and set up my next gun or let the next guys in the group go while the can cools off.

Yup, totally understand all that. The question is do people do the same with handguns? Why or why not?

 

[AJC1]

The volume of powder makes a huge difference.... 300wn vs 9mm powder volume

 

[mdi]

For load testing, I normally shoot no more than 10 shots per round, then either load magazines, a quick check of the gun, or retrieve targets. Barrels rarely get too hot to touch (even with my extra heavy 44 Magnum loads)...

 

[Ethan Verity]

Non of my sub-magnum handguns get very hot (380, 38Spl, 9mm... even 45), so I would imagine it's not as big a deal with them. My 44 Magnum definitely heats up quick though, so if testing a magnum load for accuracy I would give it a few minutes between cylinders to cool back down. When rapid firing my 44 Mag in bear-defense drills, it will become hot enough that you can see heat waves coming off the barrel!

 

[EricBu]

Yup, totally understand all that. The question is do people do the same with handguns? Why or why not?

I could see it maybe with a magnum caliber in a carbine application? For standard handgun stuff, I just don't see the heat generation being enough to really be an issue. If I was doing 50 or 100 yard testing with a TC in 44 Magnum and pushing it hard...yeah, maybe I'd cool the barrel. But a handgun with a 5 inch barrel, there's barely any retained heat there. Less powder volume, and most of the heat is dissibated in muzzle flash. You pretty much need to mag dump a 9mm to get the barrel too hot to touch....and if you're doing mag dumps, you're probably not interested in perfect accuracy.

 

[barnfrog]

That all makes a lot of sense. There's a whole lot less energy being released in handgun loads.

My Blackhawk was getting uncomfortable to touch after three or four cylinders this weekend. Didn't take as long to cool as the bolt rifle does, obviously.

So, in theory, if you were shooting enough to heat up the barrel to the same temps as rifle loads reach, would it affect handgun accuracy like it does rifle accuracy?

 

[.38 Special]

I don't think I've ever intentionally given a handgun barrel time to cool off. I suspect that a handgun barrel, being so short, doesn't significantly change vibration nodes with temperature shifts, and so doesn't show the kind of POI shifts that rifles so often do. Beyond that, I suspect that handguns (and their owners) typically aren't accurate enough for relatively subtle effects to show up on target anyway.

Now, I have heard of handguns that start to foul when very hot, and I suppose I can accept that as a true possibility. I haven't experienced it myself, though.

<edit> And yes, I get handgun barrels too hot to touch on a regular basis.

 

[Blue68f100]

A lot of that depends on the powder and caliber your shooting. TG has a history of heating up a barrel where you can not touch it without burning your self. Most powders run cooler so don't present the same problem. I normally having the barrel cool during mag changes, while I change my target. But I'm setup at my own place and time normally is not an issue. But in general if the barrel is to hot to touch you need to let it cool. I have not noticed any POI shift in my guns. Most of my POI is all shooter related.

 

[Walkalong]

I can’t shoot a handgun well enough to tell if a hot barrel has an affect.

 

[kalielkslayer]

Just my thoughts, no science here.

My rifles are tools I hope to only pull the trigger 1 time. So I want to work up a load that shoots as accurately as possible from a cool barrel. So I try to bring 4 rifles to the range with me. 1 round, take gun off of line, set 2nd rifle up, adjust the Lead Sled, bang and repeat. By the time I get back to the 1st rifle, it’s cool.

For handgun, I don’t know any scenario where I’ll only be firing one shot, at least not very often. So cooling the barrel isn’t replicating what the gun will be used for so IMHO it would be a waste of time.

That said, I try to avoid “mag dumps” to avoid excessive heat. For accuracy tests, I’ll usually Fire 5-6 rounds, slow fire, as soon as the sight picture is right, another round sent towards the target.

Like I said, no science here, just my flawed reasoning.

 

[edwardware]

Does barrel temperature, and changes in that temperature between shots and groups, not affect group size and/or POI in handguns as much as it does in rifles?

Yes, provided you account for shorter barrels.

Why or why not?

Because "as much as it does in rifles" is nearly invisibly small in pistol shooting.

I have to go to some length to notice a 0.5 MOA shift in a hunting rifle barrel due to heat. In a pistol, I couldn't detect a 3MOA shift, and likely wouldn't notice a 6MOA shift, and definitely not if I was shooting fast enough to heat the barrel up that hot.

The effect is mostly the same, but your sensitivity to the effect is far lower.

 

[EricBu]

That all makes a lot of sense. There's a whole lot less energy being released in handgun loads.

My Blackhawk was getting uncomfortable to touch after three or four cylinders this weekend. Didn't take as long to cool as the bolt rifle does, obviously.

So, in theory, if you were shooting enough to heat up the barrel to the same temps as rifle loads reach, would it affect handgun accuracy like it does rifle accuracy?

In theory, but it would be within the scale of accuracy comparitively. I mean, you're going to notice a decrease in accuracy of a 2600 fps .24 caliber bullet from a 20 inch barrel at 100 yards before you'll notice a .35 caliber from a 4 inch barrel at 1100 fps at 10 yards. I'd suspect that what you have for lunch will affect accuracy far more than barrel temps on most handguns most of the time.

 

[LaneP]

I suspect heating must have some effect on handgun groups but shorter ranges and the generally lower group expectations relative to what is expected of longer range rifle shooting, makes it less of an issue. Perhaps in precision bullseye competition.

 

[King Medallion]

I'm usually testing 3 different guns at a time, 5 shots each. Then go change targets, write down conditions on each target, (I don't have a speed checking machine, so I just kinda gauge recoil) Then I clean each barrel. After only 5 shots, barrel wasn't really hot anyway, but after all the above and the bore cleaning, barrel is cold and ready for next test load.

 

[AJC1]

What people shoot and why they are letting the gun cool matters as well. I can shoot my plinking 4227 loads in 308 as fast and long as I want. A box of 50 barely warms it to the touch.... shooting 48 grains of a slow powder makes it hot after a slow fire string of 10.... accuracy is not effected either way, but I try and take care of the throat as barrels aren't cheap. I never mag or cylinder dump, it's just not my game...

 

[Soupy44]

I've been shooting Bullseye about 4yrs now, zero mention of this. The most obsessive folks will only shoot new brass at 50y, but still load on a progressive press. This creates groups from 1911s in the sub 2in range, but has more to do with the gun than the ammo.

I was at the range today testing my revolver cylinders out of a ransom rest. Made 120 each of 3.0, 3.1, and 3.2gr under a 158gr RN in Starline brass. Shot 20 shot groups for each load out of each cylinder. Best group was about 3in. I'm told I'm doing pretty good to be under 3in at 50y in a revolver. I shot the 20 shots loading them one at a time. Didn't see any deviation between the first shots in a colder barrel and the later shots in a hotter barrel (72deg overcast day, hard to complain).

 

[The Glockodile]

None of my sub-magnum handguns get very hot (380, 38Spl, 9mm... even 45)...

...My 44 Magnum definitely heats up quick though, so if testing a magnum load for accuracy I would give it a few minutes between cylinders to cool back down. When rapid firing my 44 Mag in bear-defense drills, it will become hot enough that you can see heat waves coming off the barrel!

Same here.

I notice a bit of “binding” at the end of a box or so of continuous shooting.

Haven’t quite gotten to the bottom of it...

As far as groups are concerned, I have doubts there’d be any significant difference.

 

[GeoDudeFlorida]

Well,since you’re specifically asking about testing, the thing is, if you’re shooting high enough volume, fast enough with a “hot” powder, then I kinda have to question the testing methods. When I test handgun loads I’m shooting and reloading so slowly nothing has a chance to get hot.

 

[barnfrog]

Well,since you’re specifically asking about testing, the thing is, if you’re shooting high enough volume, fast enough with a “hot” powder, then I kinda have to question the testing methods. When I test handgun loads I’m shooting and reloading so slowly nothing has a chance to get hot.

I was testing .357 mag loads of 2400 from 13.5 to 14.9 grains with Hornady 158 grain XTPs. I shot one cylinder at a time, and I would estimate probably 5 to 10 seconds between shots. (Perhaps this provides some insight into the disappointing groups; maybe I should be taking longer between shots to get a better, more consistent hold.) Then I'd eject the empty brass, watching for signs of hard extraction, and go take a look at the target. Then back to the bench, load another cylinder and start again. Probably 3 to 6 minutes between cylinders.

One thing did occur to me: I left the cylinder in the gun with the loading gate open. The barrel would have cooled more quickly if I took the cylinder out while I was looking at the target. It was also 90 degrees, which likely didn't promote cooling much.

The barrel didn't get hot enough that I couldn't hold it, but let's just say I wouldn't put anything that warm in a crib with a baby. At least not if I gave a hoot about the baby.

 

[GeoDudeFlorida]

I was testing .357 mag loads of 2400 from 13.5 to 14.9 grains with Hornady 158 grain XTPs. I shot one cylinder at a time, and I would estimate probably 5 to 10 seconds between shots. (Perhaps this provides some insight into the disappointing groups; maybe I should be taking longer between shots to get a better, more consistent hold.) Then I'd eject the empty brass, watching for signs of hard extraction, and go take a look at the target. Then back to the bench, load another cylinder and start again. Probably 3 to 6 minutes between cylinders.

One thing did occur to me: I left the cylinder in the gun with the loading gate open. The barrel would have cooled more quickly if I took the cylinder out while I was looking at the target. It was also 90 degrees, which likely didn't promote cooling much.

The barrel didn't get hot enough that I couldn't hold it, but let's just say I wouldn't put anything that warm in a crib with a baby. At least not if I gave a hoot about the baby.

Hmmm. Well, I’d have to say it really doesn’t sound like the barrel got hot enough to change POI vs POA. With a rifle length barrel, a .1mm shift in the point of exit (muzzle) vs. POA is exaggerated by the difference between the aiming device and the muzzle. Whether you’re using a scope or irons will probably make a difference in the result, too. Obviously the difference in barrel length is going to be a factor.

 

[ballman6711]

When I load test for a pistol, I will shoot five shots, taking my time, usually about 1~2 minutes. Then I leave the slide locked open (ejection port up) while I load the next magazine, check the target, make notes, etc.... Usually about 4~5 minutes. Then I repeat this process with the next charge, and continue doing the same until I'm finished testing. Usually takes about an hour, give or take a few minutes. For a revolver, I basically do the same thing, the difference being to leave the cylinder open. Sometimes I'll do a six shot string with the revolver, but it's still usually five. Once I've decided on a load, I'll make fifty more at that charge and shoot to verify the load.

I know you didn't ask about rifle loads, but I do them the same way unless it's a hunting load. For hunting loads, I will shoot 1 shot, wait a few minutes for the barrel to cool, then repeat for a total of three shots. I want the barrel cold since that's the way it will be when hunting.

chris

 

[LiveLife]

rifle load tests ... barrel was allowed to cool between shots and groups ... handgun load testing, there is rarely if ever any mention of letting the barrel cool.

The question is do people do the same with handguns? Why or why not?

When I am testing rifle loads, I allow the barrel to cool enough so I could touch the barrel. This is done more so to remove the hot barrel variable if heating the barrel changes the barrel harmonics to increase group size. Depending on the barrel type, some AR15 barrels can become a wet noodle and really increase group size, even after shooting one 30 round magazine.

When testing pistol loads in carbines/PCCs, I considered barrel heating up as a variable but have not seen much barrel harmonics change from heating up enough to increase group size. But then again, I have not shot enough rounds during load testing to get the barrel sizzling hot.

When testing pistol loads in handguns, I don't worry about barrel heating up to change barrel harmonics enough to increase group size. If you do, then perhaps you should let your barrel cool off.

When I load test for a pistol ... I leave the slide locked open (ejection port up) while I load the next magazine, check the target, make notes

Since many pistol powders are temperature sensitive (Velocity increases with higher temperatures) and some are reverse temperature sensitive, I do not allow chambered round to get heated up as velocity variation/group size can be affected - https://www.thehighroad.org/index.p...s-and-discussions.778197/page-7#post-10117881

On really hot/cold days, I will store the test rounds inside a box/small ice chest to keep the temperature stable during the testing process as mere sun shining on the brass cases can heat up the powder charge.

 

[GeoDudeFlorida]

On really hot/cold days, I will store the test rounds inside a box/small ice chest to keep the temperature stable during the testing process as mere sun shining on the brass cases can heat up the powder charge.

I confirmed long ago the inside of my jeans pocket stays at or very close to 98F despite the outside temperature (it's Florida, we never get THAT cold or THAT hot) so I keep my next five rounds for pistol in my front left jeans pocket. Rifle is totally different: in cartridge boxes, in a cooler, only on nice days... If it's "nasty" outside and I'm not testing a hunting load, I just don't test.