New Posts New Posts RSS Feed - Pressure below -20 F
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Check GunBroker.com for SWFA's No Reserve and No Minimum bid firearm auctions.

Pressure below -20 F

 Post Reply Post Reply   Topic Search Topic Search  Topic Options Topic Options
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/26/2007 at 23:06
helo18 View Drop Down
Optics Jedi Knight
Optics Jedi Knight
Avatar

Joined: December/02/2006
Location: Montana
Status: Offline
Points: 5431
I have been reading and looking around a little, but haven't found an answer yet.  Figure you guys will know.  Why does the pressure in bullets rise dramatically below -20 F?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/27/2007 at 04:50
tahqua View Drop Down
MODERATOR
MODERATOR
Avatar
Have You Driven A Ford Lately?

Joined: March/27/2006
Location: Michigan, USA
Status: Offline
Points: 8045
Hi Helo,
Where are you getting this information? As temperatures decrease so do pressures. You've got me on this one.
 
Doug
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/27/2007 at 06:27
pyro6999 View Drop Down
Optics Retard
Optics Retard
Avatar
OT TITAN

Joined: December/22/2006
Location: North Dakota
Status: Offline
Points: 22024
doug is correct, this also explains why its a good idea to use a magnum primer when you know its going to be -20 or more to help things along a little
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/27/2007 at 07:48
Bigdaddy0381 View Drop Down
Optics God
Optics God
Avatar
Georgia peach

Joined: February/27/2007
Location: Georgia
Status: Offline
Points: 12818

I agree.the temp drops so dose the pressuers,But it still isn't a good idea to up the powder.i would do what pyro says and use a magnum primer to help things out.but i would shoot a few test loads  with the temp low to see if the POI stays the same.

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/27/2007 at 08:03
Blackbird View Drop Down
Optics Apprentice
Optics Apprentice


Joined: February/10/2007
Location: United States
Status: Offline
Points: 279
helo18, does your question have anything to do with the stainless steel Sako barrels that were blowing up a few years ago, while being shot in cold weather ?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/27/2007 at 10:49
helo18 View Drop Down
Optics Jedi Knight
Optics Jedi Knight
Avatar

Joined: December/02/2006
Location: Montana
Status: Offline
Points: 5431
I actually came across this info in an old speer reloading manual (1979 or something like that).  Made no sense to me.  Everything I have learned is what you guys are saying.  I did make me wonder though because a couple years ago I went coyote hunting at those temps, and every shot showed signs of high pressure.  Crushed or disintegrated primers and such.

The only thing that I can think of is if at those temperatures, the metal of the gun is shrinking enough to cause a tighter barrel.  My thinking may be off, but wouldn't this cause there to be more pressure created for the bullet to get pushed out the barrel.

Also how much does pressure really react to temperature?  Seems to me that it shouldn't too much because if it was really drastic, you would need different loads for different temps.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/27/2007 at 12:45
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087
different loads for different temp is a good idea, depending on your dedication level. the reference you talking about, as I recall, is the warning about using regular primers with certain ball powders, H450, and at that time ww 785. in some of the super capacity cases. supposedly the combination was causing pressure peaks. my opinion is that the deterents sprayed on the powders where "shrinking" leaving exposed particles of the faster burning nitro mix. another popular theory at that time was the slower primers where only causing a small amt. of powder to push the bullet into the lands, then as pressure built it did so abruptly rather than smoothly. something to this if you have ever had a hangfire in a 44 mag using 296.
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Similar Threads: "Pressure below -20 F"
Subject Author Forum Replies Last Post
swfa 5-20 vs minox 4-20 jladams Rifle Scopes 12
20 in barrel for 1000 yards?? bigpapa4045 Firearms 55
Hawke 20-60x85 Frontier ED ahiaring Spotting Scopes 0
Burris xtr ii 3-15 or 4-20 Oklahoma Man Tactical Scopes 3
Scope Rail 20 or 0 MOA SamC Rings and bases 22
BARSKA Blackhawk 20-60×60mm Spotting Scope johnandersonm777 Spotting Scopes 6
New 20" AR Build - Need Scope squee116 Tactical Scopes 9
Options for upgrading from a Zen Ray ED2 20-60x Marine24 Spotting Scopes 16
Bushnell Excursion 20-60x80 VS Vortex Skyline 20 rkidsfive Spotting Scopes 0
VX-3 6.5-20 VRS VX-3L 6.5-20*50 Ant264 Rifle Scopes 3


This page was generated in 0.344 seconds.