66fps swing! WOW

[Mxracer532]

Swapped back to my PRS BRA barrel and hit the range with my normal load. I was BLOWN away at the 66fps swing from 90° to 25°.
H4895
I also tested some RG4895 that I got traded some bullets for. .4g more gives the same velocity as the H4895. I ran it from 29.1g all the way to 31.0. 31.0 resulted in 2927fps.
At 30.4-30.6g resulted in 2856fps and 2857fps. This was all with Virgin Alpha Brass.

 

[xswanted]

Are you blown away “good” or blown away “upset” about the 66fps?

 

[Mxracer532]

Are you blown away “good” or blown away “upset” about the 66fps?

I wasn't expecting 66fps. I expected some speed loss but definitely didn't expect 66fps.

 

[xswanted]

I wasn't expecting 66fps. I expected some speed loss but definitely didn't expect 66fps.

Yeah that can be shocking sometimes but that’s a big temp swing. I wouldn’t sweat it too much.

The air density between those two temperatures would be much more concerning.

If your ballistic solver allows you to, enter your speed and temp at 90 degrees and 25 degrees and it should account for different temps as the temp heats up and cools down.

 

[varget204]

Figure 1 to 1.5 fps Drop every degree below 70 Degrees

 

[RAG]

Figure 1 to 1.5 fps Drop every degree below 70 Degrees

I even get closer to 2 fps/deg on my high vel varmint rigs with ball powder.

What about above 70s deg, do you get different swing per degree?

 

[JFrank]

I would not be concerned until the brass was fully fire formed and the load was stable.