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Rifles, Reloading, Optics, Equipment
Reloading
Retumbo and temps
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<blockquote data-quote="MagnumManiac" data-source="post: 1227577" data-attributes="member: 10755"><p>Temp sensitivity is blamed on so many events in shooting that quite possibly are caused by other factors, such as AIR DENSITY. I have a pressure trace also, it appears to me that air density will change a known load without there being any change in temperature. I can go from my house in the city, to my rural property, and have a gain in velocity, simply due to the higher altitude and lower air density. Air density changes throughout the day, it generally thins as they day goes, but, will thicken in the afternoon within an hour before sunset, this changes how your rifle drops, simple fact.</p><p></p><p>Darrker,</p><p>Your example of a powder cooking off in a hot chamber is not what temp stable powders are DESIGNED to withstand. They are designed to be stable in varying ambient temps, this includes being exposed to sunlight and freezing conditions. A flash over event in a cartridge is not the same as a cartridge firing at a normal temperature. There are limits to what temps a powder can withstand.</p><p>Also, lately you keep reporting that powder burn rates can vary by 10%, this is simply misleading and untrue.</p><p>By law, canister powder MUST stay within 3% of the very first batch of whatever powder was first sold as. If it doesn't meet this criteria, is blended and sold as a commercial powder. Canister powders are not blended, this has also been reported, not by you, but, needs to be cleared up.</p><p>The reason that it is recommended to start 10% below a listed max is due to the fact that a simple change in COMPONENTS, cases, bullets or primer, can change pressures by 5%, or thereabouts, which means a 10% reduction will still be safe with a load that raised pressure by that amount which can be compounded by all those changes. Also why it is suggested to ONLY change ONE thing at a time.</p><p>I have seen 8,000psi difference with just a brand change with a primer, not a type change either.</p><p></p><p>Temp sensitivity is a subject too many worry about. My best loads for my 1000yrd rifle use RE25, it is meant to be 'touchy', but, I have never seen it, even over the chrony or on the pressure trace. I've seen bigger swings from primer changes than any other factor.</p><p>I also run H1000 and Retumbo, they appear to swing with elevation and air density just as much as other non temp sensitive powders.</p><p>I have had problems in high temps with both ball and double base powders going overboard and popping primers, I learned, if you up your loads in hot temps, you won't get surprised when you switch from cold temps to hot temps, I know I no longer have to worry. </p><p>I just don't think that the temp stable thing is what is occurring in most of the so called troubles people blame it on.</p><p></p><p>Cheers.</p><p>gun)</p></blockquote><p></p>
[QUOTE="MagnumManiac, post: 1227577, member: 10755"] Temp sensitivity is blamed on so many events in shooting that quite possibly are caused by other factors, such as AIR DENSITY. I have a pressure trace also, it appears to me that air density will change a known load without there being any change in temperature. I can go from my house in the city, to my rural property, and have a gain in velocity, simply due to the higher altitude and lower air density. Air density changes throughout the day, it generally thins as they day goes, but, will thicken in the afternoon within an hour before sunset, this changes how your rifle drops, simple fact. Darrker, Your example of a powder cooking off in a hot chamber is not what temp stable powders are DESIGNED to withstand. They are designed to be stable in varying ambient temps, this includes being exposed to sunlight and freezing conditions. A flash over event in a cartridge is not the same as a cartridge firing at a normal temperature. There are limits to what temps a powder can withstand. Also, lately you keep reporting that powder burn rates can vary by 10%, this is simply misleading and untrue. By law, canister powder MUST stay within 3% of the very first batch of whatever powder was first sold as. If it doesn't meet this criteria, is blended and sold as a commercial powder. Canister powders are not blended, this has also been reported, not by you, but, needs to be cleared up. The reason that it is recommended to start 10% below a listed max is due to the fact that a simple change in COMPONENTS, cases, bullets or primer, can change pressures by 5%, or thereabouts, which means a 10% reduction will still be safe with a load that raised pressure by that amount which can be compounded by all those changes. Also why it is suggested to ONLY change ONE thing at a time. I have seen 8,000psi difference with just a brand change with a primer, not a type change either. Temp sensitivity is a subject too many worry about. My best loads for my 1000yrd rifle use RE25, it is meant to be 'touchy', but, I have never seen it, even over the chrony or on the pressure trace. I've seen bigger swings from primer changes than any other factor. I also run H1000 and Retumbo, they appear to swing with elevation and air density just as much as other non temp sensitive powders. I have had problems in high temps with both ball and double base powders going overboard and popping primers, I learned, if you up your loads in hot temps, you won't get surprised when you switch from cold temps to hot temps, I know I no longer have to worry. I just don't think that the temp stable thing is what is occurring in most of the so called troubles people blame it on. Cheers. gun) [/QUOTE]
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