Do you bother considering powder temperature shift?

[Zigjib]

I do quick little tests, usually 15 to 20 rounds, to check powder sensitivity to temperature.

After I went back to factory ammunition, i figured it's important to start doing this again as the proprietary powders ammo manufacturers use is generally not that temp insensitive compared to Hogden extreme powders.

I just chuck the info into the kestrel app for the kestrel5700 and let it sort itself out.

I recently did this for FGMM with 185gr Bergers out of my MRAD and just casually shared my results to some mates.

The response i got was "why bother when you're not really getting the temperature of the powder, just the temp of the case." Fair point but i figured convection would do its thing and i always thought SOME estimate of powder sensitivity is better than none. Attached is the data.

I just did it without really thinking about it, is this worth doing?

Cheers
Carso

Edit: to clarify, 2.72fps per °C is = to 1.51fps per °F

 

[RegionRat]

The "why bother comments" may be based on the difference in temperature of the ammo versus the shooting conditions, but that doesn't make the basic ballistics idea wrong.

If their whole point is something along the lines of popping out of a climate controlled vehicle on a hot/cold day and not knowing if their ammo temp is as hot/cold as the outside air, then I get their consternation. That doesn't mean we can ignore the problem or we shouldn't try.

If I were you, I would keep shooting and keeping notes of your DOPE and climate. It is the only way to get better at compensating for first shot DOPE in different conditions. If you want to get better at this, you have to be tenacious. YMMV

 

[MarkyMark007]

Edit: to clarify, 2.72fps per °C is = to 1.51fps per °F

I think you cant do math like this from d°F to d°C.

you must calculate how much is 5, 18 and 30°C in Fahrenheits, and than calculate velocity difference vs °F difference.

 

[diggler1833]

I certainly consider temperature sensitivity. Doing load development with a sensitive powder during the winter can get you into pressure problems in a hurry in the summer. Certain powders like CFE-223, RL-15, TAC, and AA2520 I will do the bulk of my primary load development with once it is 80*+ outside, and then tweak as necessary when it is 30* outside. I'm pretty sure my notes indicate that every one of those powders gives me at least 1.5 FPS per degree F of ambient temperature.

This is also the reason why I started migrating to powders that were significantly less sensitive years ago.

 

[ZA206]

I think you cant do math like this from d°F to d°C.

you must calculate how much is 5, 18 and 30°C in Fahrenheits, and than calculate velocity difference vs °F difference.

OP’s math is correct. In deg F, it’s a 1.51 fps/F shift rate.

 

[JerkyFreak]

I think you cant do math like this from d°F to d°C.

you must calculate how much is 5, 18 and 30°C in Fahrenheits, and than calculate velocity difference vs °F difference.

Yeah, no.

Do the conversion yourself then you'll see he is correct.

 

[Zigjib]

The "why bother comments" may be based on the difference in temperature of the ammo versus the shooting conditions, but that doesn't make the basic ballistics idea wrong.

If their whole point is something along the lines of popping out of a climate controlled vehicle on a hot/cold day and not knowing if their ammo temp is as hot/cold as the outside air, then I get their consternation. That doesn't mean we can ignore the problem or we shouldn't try.

If I were you, I would keep shooting and keeping notes of your DOPE and climate. It is the only way to get better at compensating for first shot DOPE in different conditions. If you want to get better at this, you have to be tenacious. YMMV

Yeah 100% agree and I accept that there's going to be alterations in ambient vs ammo temp, your example is a really good one - my line of thinking was some is better than none.

The temp test was just a quick and dirty for the Kestrel to start (new gun, new ammo), but absolutely agree that it doesn't stop there, i keep records.

I'm going to notch your vote as "do it, but don't stop there", which aligns with my beliefs.

Thanks mate

Carso

 

[Zigjib]

I certainly consider temperature sensitivity. Doing load development with a sensitive powder during the winter can get you into pressure problems in a hurry in the summer. Certain powders like CFE-223, RL-15, TAC, and AA2520 I will do the bulk of my primary load development with once it is 80*+ outside, and then tweak as necessary when it is 30* outside. I'm pretty sure my notes indicate that every one of those powders gives me at least 1.5 FPS per degree F of ambient temperature.

This is also the reason why I started migrating to powders that were significantly less sensitive years ago.

Agreed.

We had this issue with Mk248 Mod0 ammo. Winter and Autumn were good, summer was time to get the mallet lol.

 

[diggler1833]

Agreed.

We had this issue with Mk248 Mod0 ammo. Winter and Autumn were good, summer was time to get the mallet lol.

20-some odd years ago I had a laser of a .223 round (69gr SMK, LC brass, CCI 400, 25.5gr RL-15 @ 2.280). Developed it in February. Flattened and cratered primers a bit then. Like a moron I shot that same load in August. Significant burrs raised up on every piece of brass to the point that I junked them out of caution. It was a good lesson learned, and I am grateful that I still have my face.