- Thread starter M40_A1
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No first hand experience, but I do have a temperature sensitivity chart.
Over a range of 125 degrees F RL-15 came in at 50 fps and IMR 4064 at 46 fps, so about the same.
To put this in some perspective, H4350 was 4 fps, best and IMR 4895 was 166 fps, worst.
Unfortunately I have lost the date and source of these data.
Over a range of 125 degrees F RL-15 came in at 50 fps and IMR 4064 at 46 fps, so about the same.
To put this in some perspective, H4350 was 4 fps, best and IMR 4895 was 166 fps, worst.
Unfortunately I have lost the date and source of these data.
I've used RE15 in an AR from 27-93F.
Never missed a target from the temperature change.
Never missed a target from the temperature change.
Interesting find on the h4350. I had a 12# lot and it was about 1.25 fps\*. It was weird... It really wouldn't change alot until it got into the lower 40's. after that it was like somebody sucked the life out of it. My buddy had the same lot and it was the exact sme
Have used RL-15 for years in my AR (have tried to replace it mutiple times, but nothing hits as many targets at RL-15 does!). I see about 50fps change from 90* to 40*, or about 1 fps per degree of temp change. This is across multiple lots and many different chronos. No experience with IMR 4064 however.
Thanks for the replies so far. The reason I'm asking is that I'm switching from RL-15 to 4064 since Alliant is ignoring us. Years ago I came up with equivalent velocity loads using RL-15, Varget, and 4064. I'm into a new batch of 4064 and I'm working on matching the velocity of my RL-15 load (FGMM equivalent) again, but the temperatures now are about 25 degrees cooler than last time. If the temperature sensitivity characteristics of both powders match closely enough, then I should be able to match them side-by-side at any temperature and be close enough at any other temperature (within pressure limits, of course).
FGMM uses IMR4064 as their powder of choice. There are a few threads on here about that load.
I am right there with you. I was using Winchester 748 for years but have not seen it for sale in quite a long time so I changed to IMR 4064. Although it is a pain to load, as it is an extruded powder, it seems to be very temp insensitive and has gained me some fps in my rifles. I used 44GR of 4064 in a Lake City LR brass and was getting 2650 with a 175 Sierra out of a 20" barrel and just under 2750fps out of a 24" barrel. I happened upon it because it was available and have been pleasantly surprised.
During these times you better have multiple loads from different powders to keep shooting.
During these times you better have multiple loads from different powders to keep shooting.
Back in the 1990s I determined that 4064 was basically the powder used in 168 gr. FGMM. That was before the 175 SMKs came out. I don't know what Federal is currently using in 168 gr. GMM.
A few years ago I determined that Federal was using what was basically RL-15 in their 175 gr. GMM, definitely wasn't 4064. I found information that confirmed that. However, the powders they use are not necessarily the exact same that we can get.
There is no one definitive load, as the load has to change from lot to lot of powder in order to maintain the same velocities. That's basically what I'm doing. I found 41.2 grains of 4064 to equal 175 gr. FGMM factory loads, and so did 42.8 gr. RL-15. But, that was only for the lots of powder I had at the time, and at that temperature. Now I'm changing from RL-15 to 4064, and a different lot of 4064 at that.
I was using Re15 in my 308 until I ran out. Accuracy was great, but I was having to swap out my FDAC cards due to the velocity variations as the temp changed. I switched to 4064 last fall, and have used only the 2600 fps card since. FYI I used the same chrono for all loads, fired from the same rifle, and I didn't consider the velocity changes to be a deal breaker but it was definitely something to be aware of.
