Accuracy or temp sensitivity

[Dadof4girls]

I ran a ladder test with 2 different powders. H322 & CFE223. The cfe had a better grouping than the 322 but I have seen a diagram showing 1.7fps per degree. I had a 1.03moa across 3 charges with 2 being .32 while the 322 was 1.07 with 3 and the closest 2 being .97. The charges are in .3grn steps. Velocity is a wash between them. So my question is would you give up the potential .6moa for temp stability or just build dope cards for several different temps. My temp range will be 20-90 but would mostly be around 30-60. It was around 25 when I tested the loads.

[Texas]

Regardless of the powder,temperature is part of the formula for trajectory. Temperature affect air density which affects friction.

[StoneHendge]

I have found CFE to be more around 1fps/degree. Accuracy seems to hold down into the mid 40s with a load developed in the mid 70s. The problem your going to face is increased pressure as it warms up with the CFE.

[biodsl]

So my question is would you give up the potential .6moa for temp stability or just build dope cards for several different temps.

Only you can answer that question.

Here's a drop chart I did for my load of 31.2gr of CFE over a 123gr Amax. I used the JBM calculator and have verified some, but not all, of the velocity numbers in the field. Still some work to do there.
DropChart.jpg

https://www.youtube.com/watch?v=711L4ezpuCw

Here's the video and template to help. It seems like a lot of work but is actually kind of fun and rewarding when you get to use them in the field.

[NugginFutz]

You didn't mention the bullet weight, but with respect to the rest of your information, consider the following.

I've shot both powders to great success. H322 seems to really shine with the lighter projectiles, whereas the CFE223 appears to prefer the heavier pills. In my experience, H322 is extremely consistent over a wide variety of temperatures. CFE233 noticeably less.

You've just shot groups with both powders at the low extreme of your projected temperature range, and presumably have data for a series of velocities at that temperature.

Further, you are presuming that the accuracy of both powders will remain consistent at the those same charge levels when the temperatures rise to the upper extreme of your projected shooting temperatures.

Finally, you appear to be willing to extrapolate your anticipated velocities at those temperatures based on the temperature sensitivity data from the chart to which you referred. Those temperature variances in that chart are likely an average of different sources, and may or may not accurately relate to your particular weapon.

In my opinion, other reloaders' experience not withstanding, unless you reshoot groups when the temperatures are higher, you are only speculating on the performance of either powder across that wide of a range.

[Dadof4girls]

[LR1955]

This is with 107 smk. I realize that temp has to be figured into the drop regardless just was thinking having to figure the change in powder and temp would add some difficulty to it. Just having trouble getting past the possibility of giving up .6moa. Looks like I need to load and shoot a few groups with both powders. I’ve also wondered how far you would have to be below max with the cfe to be safe during the summer. I know that I can go at least .7 higher without getting pressure signs.

DOFG:

You need to test both loads at 300 and see which one shoots better. The one that shoots better at 300 is your choice, no matter what its theoretical temperature sensitivity may be. If you can't get to a 300 yard range (or longer) then go with the one that shoots the best. You see, if you can't practice at distances where you think such minor things will bother you, then you are only taking a guess if you have to actually shoot that far. And at the distances where the change in velocity due to powder temperature makes a difference are so far that the low velocities of the Grendel combined with things like haze, mirage, and dust, plus winds will wash out any change in velocity due to powder temperatures as a factor in your success.

LR55