How hot to shoot?

[Vicodan]

Doing some HVAC work, I picked up both an Infrared thermometer and a Multi-Meter thermocouple. I can use either to get an exact temperature reading on my barrel instantly. So, here's the question- How hot should I shoot my barrels? I would take readings at the throat area, where Temp should be highest. I am thinking 416

The question comes up in multiple facets.

1. During load development, what Temperature will affect accuracy? As in, can I shoot 1 group before cooling, 2 groups, etc?
2. What does the Temperature versus barrel wear relationship look like?

 

[Alex Wheeler]

Your asking questions that I have never seen published data on. Your gonna get a lot of opinions. That said, you have the equipment to do a good test and tell all of us the answers! But in general the answers are going to vary wildly by barrel contour and cartridge I assume.

 

[Vicodan]

My parents always said I had a question for everything.

I'm always trying to break the shooting sport down into it's scientific components.

In this instance, I would need far more equipment than a thermometer to get any sort of accurate data,

 

[Tempest]

Agree with above. I've never checked it (I've thought about it) but I do know my .338 POI starts to walk after 10 shots. Barrel gets extremely hot to the touch. So I typical limit shots to 5 round groups at a time.

Don't have that luxury in F class when you are shooting 20+ sighters. It is, what it is.

 

[wapiti25]

At about 400* powder will ignite. I would not want my barrel to reach 150*, when it is too hot for my hand that is hot enough.

 

[Mozella]

Many people say it's too hot when you can't hold it for very long. Some folks swear that their accuracy goes wacko when the barrel gets real hot. Others claim that their rifle holds zero even when it starts to smoke. Both may or may not be correct. Bottom line: Expect a lot of answers but don't expect to find Nirvana.

Since you have all the fancy equipment, plus an interest in this subject, why don't YOU conduct some scientific tests of your own and report back to the rest of us. Remember, you're looking to find what are likely to be TINY deviations in precision, so you MUST test with the very best ammo you can make under perfect conditions. Then you MUST measure the results carefully.

Use a scanner and On Target software (or some similar system) to measure your groups. Using a coin or a carpenters tape ain't gonna cut it. Then put the results into a spread sheet for further study.

You may possibly come up with an answer, or the results might just get lost in the noise associated with trying to gather data involving a human aiming a gun which delivers a bullet propelled by a cartridge subject to many different possible variations to a target many yards away through an atmosphere full of unknown winds. Teasing the truth out of this kind of situation ain't gonna' be easy, especially if you don't use your very best scientific methods.

Good luck and please report your findings.

 

[Sniper338]

I do this regularly when load developing. I have the infared thermometer, check chamber temps, check ammo temps...

Starting out you want your barrel, and ammo ambient temp... if its 100 outside, I like to let everything settle in to the 100 ambient temp..

Fire a shot, and wait until temps get back to about 100 in your chamber. (since 100 is our theoretical ambient temp) then I shoot again and wait a bit...

When ots 100+ a barrel heats up FAST, so I fire slow strings.. keep the ammo out of the sun too...

Ive shot many .1+- groups doing this.

Going slow and checking temps insures your ammo isnt heating up fast in your chamber... keeps everythin consistant this way..

Then when you got your 5 shot group done in about 10 min.... wait a little bit before starting the next test load, then repeat..

I keep data on it all too when I shoot... at this temp, this load shot this fast... then you know what your load and powder does in different temps down the road when you get several sets of data together in different temps. You can do a muzzle velocity line graph... kinda fun to play with the data...

Thats how I know RL15 is 1fps change per degree up or down in temp

 

[Intheshop]

150 yd range,"out the back door" of shop.Interestingly,because I only shoot cast is that the heat,even with reduced loading of 2200-2800 fps....is still a factor.

I have two distinct methods.

#1,really long cooling periods between shots.Basically catch a calm condition day,work in shop,going out and cut one loose.Back to work...repeat.

#2 Somewhat forget the conditions (up to a point)...send 5 downrange as fast as possible.

Both will work,both "should" teach you something.After 40 years of practice,I prefer #2.Good luck with your testing.

 

[Joe Salt]

I know after shooting 18-20 rounds in 1000 yard matches the barrel on my HG. which is 1.45" gets worm enough that you don't want to keep your hand on it for any length of time. My LG. with the barrel at .900" at the muzzle you do not want to grab with your hand after that many rounds. But let me tell you this my buddy has a Palma Barrel on his LG. and shoots as many rounds as I do, and I know I wouldn't touch it. But that Damn thing is kicking A$$ at 1000 yards, so as far as heat goes other than Maybe wearing the barrel out a little faster I don't know what temp. to keep them at. Oh and my buddy's rifle is on its third year and it's a Dasher. And the match before last he beat me out of HG. group and score for the day with a 4.5" 100 so if you come up with the answer to heat I'll listen.

Joe Salt

 

[Vicodan]

I can't wait until winter. Load development takes 1/10 the time.

 

[Milo 2.0]

I can't wait until winter. Load development takes 1/10 the time.

Load dev in the winter time can seriously bite your butt come hot days, even with temp stable powders.

 

[LCazador]

Doing some HVAC work, I picked up both an Infrared thermometer and a Multi-Meter thermocouple. I can use either to get an exact temperature reading on my barrel instantly. So, here's the question- How hot should I shoot my barrels? I would take readings at the throat area, where Temp should be highest. I am thinking 416

The question comes up in multiple facets.

1. During load development, what Temperature will affect accuracy? As in, can I shoot 1 group before cooling, 2 groups, etc?
2. What does the Temperature versus barrel wear relationship look like?

There are too many variables involved to answer your question. Here are some factors involved: ambient temp, barrel steel, barrel weight, grains of powder, and even bullet seating depth can come into play. Bullet seating depth creating higher pressure and in turn higher temp. I did a test years ago using an infrared thermometer. Two barrels in 6.5/284S, average of 50gr. of 4831SC. One barrel a straight taper 1.250", the other a heavy Varmint, both 30inch. I shot the heavier barrel hotter, thinking it would dissipate heat faster. While the heavier barrel seemed to run cooler on the outside, the internal temp was very similar on both barrels. Heavy barrel went out at 900 rounds, lighter barrel ( shot at much cooler temp, 5 shots max before cool down) still shooting at 1200 rounds. Monitoring groups between the two was very difficult. Changing wind conditions and temp had too much effect to prove a scientific outcome. Some barrels shoot better as the bore heats up, heat expands the bore. The big question is; how hot before the projectile starts deforming? A temp over 130 is too hot to hold in your hand, a temp over 150 degrees Fahrenheit can burn and can damage your barrel much quicker!

 

[Sniper338]

Allowing the barrel to cool down to ambient temperature is a "cold bore shot". Doing so each shot as you suggest may be effective for single shot scenario's (like hunting, etc.), but in my experience will not provide intel for string/group shooting and would grossly be an inefficient method for load development to any thing other then single shot desires.

In my experience, how the barrel will react and what the loads accuracy potential to a string/group, are better found by simulation of nearer the same barrel heat and round counts to what they will be used for. Shooting a test string fast will not heat a barrel all that much more then single shot/slow methods, since barrels heat up more after sitting for a bit. Very dependent on barrel contour and testing ambient of course, but short strings of 5 to 15 shots fired in say 1-minutes time or less in match barrel contours, is the most efficient and effective way to load develop and "beat the heat" in my experience.

My match barrels are never fired at "cold bore" temperature during the record strings, there for in load development I also want to simulate and pre-heat the barrel to an "operating temperature" with X amount of sighter's immediately before the string test. After each string test and those preliminary sighter's , I then allow the barrel to cool down to near ambient before starting the next string/group test.

My 2-Cents,
Donovan

Honest I havent found it to be a problem. After load development the way I do, I shoot strings, and they all hammer even when the barrels hot. I just try not to heat up a barrel as much when its not necessary.. I havent gone over 20 shot strings such as in a match though... just aint necessary

 

[Sniper338]

Allowing the barrel to cool down to ambient temperature is a "cold bore shot". Doing so each shot as you suggest may be effective for single shot scenario's (like hunting, etc.), but in my experience will not provide intel for string/group shooting and would grossly be an inefficient method for load development to any thing other then single shot desires.

In my experience, how the barrel will react and what the loads accuracy potential to a string/group, are better found by simulation of nearer the same barrel heat and round counts to what they will be used for. Shooting a test string fast will not heat a barrel all that much more then single shot/slow methods, since barrels heat up more after sitting for a bit. Very dependent on barrel contour and testing ambient of course, but short strings of 5 to 15 shots fired in say 1-minutes time or less in match barrel contours, is the most efficient and effective way to load develop and "beat the heat" in my experience.

My match barrels are never fired at "cold bore" temperature during the record strings, there for in load development I also want to simulate and pre-heat the barrel to an "operating temperature" with X amount of sighter's immediately before the string test. Then after each string test and those preliminary sighter's , I allow the barrel to cool down to near ambient/cold-bore before starting the next string/group test.

My 2-Cents,
Donovan

And you are right, it does help with cold bore shots. As I like accurate cold bore shots too, gives you a secure feeling hunting...

 

[Medic505]

I havent gone over 20 shot strings such as in a match though... just aint necessary

I'm curious, how many F class matches have you shot?

 

[Sniper338]

How do you deal with condition changes and the allotted time needed to single shot develop?
More so in summer months, but it could literally take me hours to conduct a single test utilizing your single shot + wait method, that could easily be plagued and scrutinized by condition changes.

Each to our own and maybe just me, but I don't get the why or the inefficiency to such a method.
Especially for competition shooting, as is the OP's question.
Donovan

After I find a load, I shoot and chrono year around in different degrees... 30-110 degrees usually.. i record the daya from the chrony in a spiral notebook for each rifle I have. With that data I have excell programs I can enter the data into and get muzzle vrlocity curves, drop charts, everything... so I know when I go out what 40 degrees will do to ambient ammo and barrel on a cold bore shot, vs 85 degrees, same deal... yes it does take lots of time... no arguement there. But its pretty neat to have accuurate charts for long range steel and hunting...

The charts help some for a competition match, to get dialed in, but sfter that its sighters... not really competition useful for f class, agree there too.

 

[Medic505]

I havent gone over 20 shot strings such as in a match though... just aint necessary

Again, how many F Class matches have you shot? Dodging my question?

 

[Milo 2.0]

After I find a load, I shoot and chrono year around in different degrees... 30-110 degrees usually.. i record the daya from the chrony in a spiral notebook for each rifle I have. With that data I have excell programs I can enter the data into and get muzzle vrlocity curves, drop charts, everything... so I know when I go out what 40 degrees will do to ambient ammo and barrel on a cold bore shot, vs 85 degrees, same deal... yes it does take lots of time... no arguement there. But its pretty neat to have accuurate charts for long range steel and hunting...

The charts help some for a competition match, to get dialed in, but sfter that its sighters... not really competition useful for f class, agree there too.

For 700 bucks you could crumple paper from that notebook and use as fire starters and be 10 times better off. I honestly think this was the smartest money I've spent since getting into LR shooting.

 

[Sniper338]

For 700 bucks you could crumple paper from that notebook and use as fire starters and be 10 times better off. I honestly think this was the smartest money I've spent since getting into LR shooting.
View attachment 1019197

I have a kestrel, just not the one that hooks up to everything... lol. Working with what I got!! Lol

 

[T-shooter]

I can't wait until winter. Load development takes 1/10 the time.

If you can, it's good to use a barrel cooler. In 90* weather I can cool the barrel on a .308 in 60 seconds or less between shots, vs 5-10 minutes. My temp gauge is if I can hold the barrel without being too uncomfortable, maybe 100 ° to 105°. Use a high volume / low pressure 12v air pump and a piece of 1/2" soft thick walled plastic tubing, run it into the chamber and it blows the hot air out through the muzzle cooling the hottest portion first. Any 12 volt power source that you can plug into will work. You could also adapt a small filter on this blower if you are in a dusty area.


Another power supply that would work.