OCW test in cold weather

[bstomper]

I have my OCW rounds made and will head out this coming weekend. It -20c out right now and have a question about the temperature. Should I let my gun and ammo adjust to the outside temperature before doing the test or keep them warm (in the truck) in between shot groups or will it make a difference.

 

[Rich Coyle]

tag

 

[bstomper]

tag

???

 

[dsculley]

It may/probably make a difference depending on how sensitive the powder is to temperature. If these are going to be hunting rounds to be used in similar cold weather, I would just test in ambient temperature. You just need to be aware that the pressure will probably increase if you then use this load in much warmer temperature.

I live in the Southeastern U.S. and we can have wide temp swings in the winter. May be near freezing today and near 70° F tomorrow. I always try to test in warm weather so I don't have to worry about over-pressure from temperature changes.

If your powder is very temp sensitive, then you want to KNOW they will group in the temp you expect to use them. Even the "Temp Stable" powders can be affected by wide temp swings.

FWIW

 

[bstomper]

The temps I hunt can vary from 15c (60f) to -25c (-13f) depending on what I am hunting, elk, moose ,deer. I also do some shooting in the summer. I am using hodgdon H1000 for this load development and from what I found in my research, it is suposed to be fairly temperature stable. Would it make sence to keep the cartrages warm in the truck the best I can, at least till I see if there are any pressure issues,. Once I find out the max load ( because of pressure issues) I can let thing cool down to ambiant temps and finish the test. Does this make sence??
I'm new to this stuff and trying to learn.

 

[dsculley]

That would be an acceptable method. Where you get into trouble is testing in cold weather, working up a load near published max and then shooting that load in much warmer weather.

Your method will work based on what you described. I would probably put the rounds in a small cooler when I left the house. I would have about 4-6 fouling rounds to get the chamber up to temp, then test. You might consider letting the rounds sit in the heated chamber for a minute or so as well. Common sense goes a long way in this hobby. Sounds like you have a good dose of it and are trying to apply sound reasoning.

Even though H1000 is considered to be temp stable, that is a large temp swing (40° C or 73° F) so you can probably expect some difference in pressure/MV going from one extreme to the other. The only way you will know is to test at each extreme, however you should be able to get a satisfactory hunting load with the method you described.

 

[Dosh]

tag

When someone "tags" a thread, they have an interest and are "tagging" along to learn info on the subject. It's like marking a page in a book, you know where to find it.

 

[bstomper]

Good to know. Thanks guys

 

[Rich Coyle]

When someone "tags" a thread, they have an interest and are "tagging" along to learn info on the subject. It's like marking a page in a book, you know where to find it.

Every time someone posts on this thread I receive an email alerting me. I click on the email and it takes me here.lightbulb

 

[bstomper]

Cool. How do you tag a thread. Would come in handy.

 

[philipbrousseau]

by making a post on the thread of interest. now that i've posted this i'll get an e-mail every time someone posts on your thread.

 

[Hawk in WY]

Others posted before I got this together thinking I would be the first to reply. Some redundancy, but you might as well hear another voice.

All powder is temperature sensitive to some extent. Lower velocity at lower temperatures. Some more so than others.

The answer to your question depends to some extent on the powder you are using.

In general developing a load at -20 and expecting to shoot at +60 is probably not a good idea.

If you plan to shoot at -20 leave the gun and ammunition outside for awhile.

If you plan to shoot from your truck, leave both in the truck.

Interesting to observe bench rest shooters storing their ammunition in small coolers during matches on hot days.

Good luck.