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Cold weather Chronograph results.

 
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  #1  
Old 12-18-2012, 09:31 PM
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Join Date: Nov 2012
Location: Copper Basin, Alaska
Posts: 682
Cold weather Chronograph results.

As it turned cold again I was staying home today to keep the house warm. I figured it would be a good time to do a little Chronographing. I put the rifle and ammo outside for 45 minutes with the bolt open. I got the chrony ready and went out in the yard with chrony and rifle. Set chrony down, turned it on backed off 18' and commenced fire.
Temperature -40f
Rifle, Ruger M77 Hawkeye Stainless
Cal. 6.5 Creedmoor
bullet, 110 gr Barnes Banded Solid moly tumbled
Powder, Varget. 39 grains
Primer CCI 200
1, 2931 . 2, 2931 . 3, 3007 . F. P. S .

I have chronographed this load at 40f and got
1,3040
2, 3020
3. 3034 .
Same distance to chrony.
I didn't have any high pressure signs and I don't think I'm at Max.
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  #2  
Old 12-19-2012, 01:29 PM
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Join Date: Oct 2007
Location: Tillamook, Oregon
Posts: 381
Re: Cold weather Chronograph results.

It appears that you are experiencing powder temp sensitivity. I don't have experience with the powder you are using, but with 100fps difference between the 40 and -40 this is probably what you are running into.
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  #3  
Old 12-19-2012, 02:20 PM
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Join Date: Dec 2010
Location: West Texas
Posts: 74
Re: Cold weather Chronograph results.

Interesting. Thanks for sharing the results, I've been curious about how much the temperature swing will affect muzzle velocities myself lately. I assume that the 3007 fps was either after the gun warmed up the powder a little or you had it in your pocket or something different? Seems like a bit of an outlier..

Your -40 comments are making me not dread +20 as much now (where I'll be heading in a couple weeks). I just thought I got cold around here when it starts dropping below 45 or so.

Quote:
Originally Posted by Cold Trigger Finger View Post
As it turned cold again I was staying home today to keep the house warm. I figured it would be a good time to do a little Chronographing. I put the rifle and ammo outside for 45 minutes with the bolt open. I got the chrony ready and went out in the yard with chrony and rifle. Set chrony down, turned it on backed off 18' and commenced fire.
Temperature -40f
Rifle, Ruger M77 Hawkeye Stainless
Cal. 6.5 Creedmoor
bullet, 110 gr Barnes Banded Solid moly tumbled
Powder, Varget. 39 grains
Primer CCI 200
1, 2931 . 2, 2931 . 3, 3007 . F. P. S .

I have chronographed this load at 40f and got
1,3040
2, 3020
3. 3034 .
Same distance to chrony.
I didn't have any high pressure signs and I don't think I'm at Max.
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  #4  
Old 12-19-2012, 03:34 PM
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Join Date: Nov 2012
Location: Copper Basin, Alaska
Posts: 682
Re: Cold weather Chronograph results.

Yes, the 3rd round was in the chamber for close to 1 minute. It took me a short time to check the chrony to make sure there was no error. Plus as it was in the bottom of the mag I think it hadn't got quite as cold as the 2 above it.
Some may think the 100 fps velocity drop is significant. And in some ways it is, but lots of other powders will loose 200-400 and more fps of velocity drop and will blow so much unburnt powder out the muzzle that a Chronograph will always show an error unless it is put ay 25-30 yards from the muzzle.
RL 15 is pretty bad in the cold (-20 and colder)
I've had hang fires with BLC2.
For me as a hunter, 2900 fps is still very useful velocity.
My goal is to record the real velocity drop so that I can figure the poi drop and wind drift. At the different temps.

And a guy told me that some of the custom barrel makers won't ship stainless barrels up here because they say they will shatter in the cold.
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  #5  
Old 12-19-2012, 08:49 PM
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Join Date: Oct 2007
Location: Tillamook, Oregon
Posts: 381
Re: Cold weather Chronograph results.

FWIW, this is the reason I switched to Hodgdon's extreme powders a few years ago. They are probably the most consistent powders when exposed to large temp swings like what you are talking about. I have been very pleased with H1000 and don't see myself changing powders again, very consistent.
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  #6  
Old 12-20-2012, 12:41 AM
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Join Date: Dec 2010
Location: West Texas
Posts: 74
Re: Cold weather Chronograph results.

Are either of you familiar w IMR 4831 and how it handles extreme cold?
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  #7  
Old 12-20-2012, 01:20 AM
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Join Date: Oct 2007
Location: Tillamook, Oregon
Posts: 381
Re: Cold weather Chronograph results.

Quote:
Originally Posted by Huntin Fool View Post
Are either of you familiar w IMR 4831 and how it handles extreme cold?
No, the only IMR powder I've used has been 7828SSC that I used in a friend's 300 Win. I have not tested the velocities at extreme temp changes.
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