Testing loads in the heat of sumer

[Mark in Mo]

What effect does the heat of summer have on working up loads? I have been trying to work up loads in temps of mid 80's and seem to have inconsistent results. I have been working with 3 shot groups waiting about 2 min between shots and 7-10min between groups allowing the barrel to cool. Seems that when a load shows promise the next time out the load opens up

Do you guys find that your hunting load used in colder temps shoot well in the hotter temps of summer?

Any input would be great

Thank you

 

[davkrat]

You run the risk of being over pressure depending on the powder you use when taking a cool weather developed load and shooting it in summer heat. Some have posted on here to test loads by placing a few in an ice chest to cool them way down and compare the velocity and pressure signs you get. Another tip I plan to incorporate I read on here is to use some sort of CO2 compressed air or a battery powered inflatable pump to push cool air down your barrel. I've rubbed wet rags on the outside of my barrel to cool it in extreme heat. Seems when temps are in the high 90's plus you cannot cool down a barrel in any reasonable time. I shoot lots of .22 in between shots of centerfire but that can take a long time and with rimfire being so hard to find these days it's nearly impossible.

 

[USCGLongBow]

Re: Testing loads in the heat of summer

What chamber? I know in my experience, anything hotter than a .243 Win I need to space my 3-shot strings over a minimum of 15 min to get ANY kind of consistency. My .338 RUM and some of my bigger guns I need to give 15 mins between shots when temps get above 85, so during hot weather I typically will only shoot one string a day. Another thing I avoid is artificially cooling the barrel, I.E. setting it in front of a fan, setting it on the front seat next to a running AC, wetting the barrel. For me, this seemed to make my groups more inconsistent than letting the barrel air-cool, so I avoid doing it. If I am in a hurry I will take it into a range office with a cooler temp as long there are no felt air currents, or I have set a rifle in the backseat or trunk of a hatchback to cool away from any air vents. Just my .02, I'm sure you will hear a lot of different opinions.

 

[FearNoWind]

Some powders are more temperature sensitive than others. But 80 degree ambient temps. shouldn't make that much difference. Everything you do in load development (position, rest, gun handling discipline, weather, wind, etc.) effects both accuracy and precision. It may not be the load.

 

[idaho elk hunter]

I use compressed "AIR?" made for blowing off electronics such as computer key boards. I blow it down the barrel quickly after each shot an leave your vehicle running AC on high. This works best if your testing 3 firearms in one session and rotate between shots. This should cure it. If it does not then buy a Weatherby.

 

[Mark in Mo]

I think I need to quit until it gets cooler out! Just seems to be a PIA and a waste of components lol!

 

[FEENIX]

I think I need to quit until it gets cooler out! Just seems to be a PIA and a waste of components lol!

There you go! I shoot for fun (.22s, .223/5.56s) on hotter part of the year and normally under the shade and in the AM.

I do occasional load development but fine tune it when it is cooler and getting closer to hunting season.

Check out #2 of this thread >>> http://www.longrangehunting.com/forums/f28/powder-temperature-sensitivity-31096/

Good luck!

 

[SAM1980]

I'm currently doing load development for my 30.06. Have been for the past few months. Something that I am banking on for this years hunt is using powders from Hogden's extreme line of propellants. They claim to be less temp sensitive than other powders. That's my plan anyway. And we all know what they say about plans! That and never pee into the wind!

 

[AZShooter]

Testing at 80? Heck that is the temperature when we start. We often get into the mid 90s before we quit around 10 am.

If you use extreme powders it will help. I have used Varget in temps up to 103 and never saw a difference down to 30 degrees at the 200 yd range with a 22-250.

IMR 8208 XBR their description says: "The ballistics group at IMR has tested this powder from -40 to +165 degrees Fahrenheit with virtually no performance variation. " I use this in my 308 and am very happy. Untitled Document

Naturally I also test my loads in cooler temperatures to check the performance. I have a few rifles that aren't shot in the summer.

I have used wet rags, and even ran water over the barrel with synthetic stocked rifles. We used to have an refrigerated water fountain. Nothing was faster.

I have heard that running water through the barrel is a way that several gun writers used to do it. Rick Jamison used a hot water bottle hung high with a clamp on the hose which fits into the chamber. He would keep the bottle in an ice chest till he used it. All it took was a few patches through the bore and he would shoot again.

I currently use a CO2 tank.

 

[dig]

Re: Testing loads in the heat of sumerpp

I work up loads in our Arizona summer all the time. The big issue is cooling the rifle. Placing it in an A/C vehicle between strings helps. It heats up quick and as soon as you load the case absorbes that heat. I load singles and try to shoot fairly quickly As for pressure, yes it may rise slightly, I have experienced this way more with factory loads, Weatherby to be precise. And we are talking 90 plus. Hand loads I get about 40 fps difference between 100 degree temps and 70's with magnums using Retumbo and H1000. As for 80 degree temps, I would not worry to much about pressure. You may experiance a velocity drop if you go down 30-40 degrees but it will be minimal. Kee thing unders shade and just check them in the winter months.

 

[Mark in Mo]

Thanks guys...Think I will practice a little more patience or wait till cooler weather!