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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
RL33 Temperature Regression Thread
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<blockquote data-quote="jmden" data-source="post: 947362" data-attributes="member: 1742"><p>There has been talk of RL33 perhaps showing less temp sensitivity with minimum bullet jump. Do a search or two on this site as there was a really good thread or two that seemed to show this fairly prominently. And, many have found this powder to be very temp insensitive in their load/rifle and others just the opposite. What's the difference? One aspect could be seating depth. Other aspects could come from the variables we may be inadvertently introducing to our testing as mentioned below possibly resulting in worthless or next to worthless data. Food for thought...</p><p></p><p>I've come to realize lately that having your ammo at a certain temp and your gun at a certain much different temp (how often does that happen when hunting anyway?) potentially introduces all kinds of variables when checking velocity to the point that the data may be irrelevant. What we may need to do is have both ammo and rifle at the same ambient temp and test in warm and then in cold ambient temps. Otherwise, with expansion and contraction of bore and bullets in different temps we may just be producing worthless data as bore and bullet dimensions change in different temps. If you've got a warm bore (possibly small amount of expansion) and a cold bullet (possibly small amount of contraction compared to what to it would be if it was at the same warmer temp the bore is at), we may be causing pressure differences simply based on the physics of metal contraction/expansion that messes with the pressures in the bore and the resultant velocity creating useless data. Guys blowing primers in cold temps or just seeing higher velocities at cold temps, the latter of which is apparently not unusual, could simply be from a slightly contracted/smaller bore due to cold temps. That'll raise pressure fast. Some barrel metals/alloys may be more affected by temps than others? I don't know, I just think that instead of trying to isolate the variable of powder temp by warming or cooling ammo (something I'd done for years), we are actually increasing the variables in the system and in an artificial, arbitrary manner likely resulting in bad data.</p><p></p><p>I understand the idea of trying test what the powder does in different temps, but that's just one variable in the entire system and trying to isolate that may not be realistic or give usable data. This was hashed out on another site lately and I had my ideas about this changed.</p><p></p><p>Shoot at ambient cold and hot with rounds and rifle at same temps (as would most likely be the case in a hunting situation) and see what happens. It may not be as convenient as simply putting rounds in a cooler, but I believe the resulting data will likely be more accurate and realistic and perhaps actually show what the entire system is doing. </p><p></p><p>Not sure I've done a good job of trying to explain this. If so, I apologize.</p></blockquote><p></p>
[QUOTE="jmden, post: 947362, member: 1742"] There has been talk of RL33 perhaps showing less temp sensitivity with minimum bullet jump. Do a search or two on this site as there was a really good thread or two that seemed to show this fairly prominently. And, many have found this powder to be very temp insensitive in their load/rifle and others just the opposite. What's the difference? One aspect could be seating depth. Other aspects could come from the variables we may be inadvertently introducing to our testing as mentioned below possibly resulting in worthless or next to worthless data. Food for thought... I've come to realize lately that having your ammo at a certain temp and your gun at a certain much different temp (how often does that happen when hunting anyway?) potentially introduces all kinds of variables when checking velocity to the point that the data may be irrelevant. What we may need to do is have both ammo and rifle at the same ambient temp and test in warm and then in cold ambient temps. Otherwise, with expansion and contraction of bore and bullets in different temps we may just be producing worthless data as bore and bullet dimensions change in different temps. If you've got a warm bore (possibly small amount of expansion) and a cold bullet (possibly small amount of contraction compared to what to it would be if it was at the same warmer temp the bore is at), we may be causing pressure differences simply based on the physics of metal contraction/expansion that messes with the pressures in the bore and the resultant velocity creating useless data. Guys blowing primers in cold temps or just seeing higher velocities at cold temps, the latter of which is apparently not unusual, could simply be from a slightly contracted/smaller bore due to cold temps. That'll raise pressure fast. Some barrel metals/alloys may be more affected by temps than others? I don't know, I just think that instead of trying to isolate the variable of powder temp by warming or cooling ammo (something I'd done for years), we are actually increasing the variables in the system and in an artificial, arbitrary manner likely resulting in bad data. I understand the idea of trying test what the powder does in different temps, but that's just one variable in the entire system and trying to isolate that may not be realistic or give usable data. This was hashed out on another site lately and I had my ideas about this changed. Shoot at ambient cold and hot with rounds and rifle at same temps (as would most likely be the case in a hunting situation) and see what happens. It may not be as convenient as simply putting rounds in a cooler, but I believe the resulting data will likely be more accurate and realistic and perhaps actually show what the entire system is doing. Not sure I've done a good job of trying to explain this. If so, I apologize. [/QUOTE]
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