Re: Altitude vs Chamber Pressure
Here is a question and Lindy's excellent answer regarding "Shooting in a down pour".
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Question (editted for personal info):
Lindy,
A buddy of mine was shooting in a practice for a tactical match. The heavens really opened up and everything was soaked. He was not able to keep either his ammo or chamber dry.
His reloads which were specifically loaded for long range accuracy began to blow primers. Those loads were still very accurate, but obviously at much higher chamber pressures.
He has asked me <span style="color: #FF0000">if a milder load would be the answer to not blowing primers - or - will he always have overpressure problems when shooting in a downpour?</span> Waiting for a sunny day is not a viable option as he live in the Pacific Northwest where the rainy season is from 1 Jan to 31 Dec.
His rifle is a 300 Win Mag AI AWSM.
Any help would be greatly appreciated.
Thanks!
<span style="font-weight: bold"><span style="color: #000099">Lindy's Most Excellent answer</span></span>(Key point I was looking for is highlighted in red):
If your ammo and chamber are wet, you're going to have pressure problems. The reason is that water is relatively incompressible, so any water on the ammo and in the chamber takes up space that is not available for the case to expand into.
Less space - more pressure.
<span style="color: #FF0000"><span style="font-weight: bold">Loading down is not the solution. The only solution is to keep your ammo and chamber dry.</span></span>
Shooter's at Bisley in the U.K., where it rains a lot, often tape a piece of Naughahyde or similar heavy waterproof material to the left side of their receiver, then drape it to the right over the scope, sheilding the ejection port from the rain, but still allowing them to reach up under the fabric to manipulate the bolt. And keep the ammo out of the rain.
In combat, of course, you shoot when you have to.
Regards,
-- Lindy
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I hope this helps out!