Staball 6.5

[Torque]

I am trying to develop a load for 25 Creed using 120g Partitions. I know these are not the most accurate of bullets, but they are great on game.

I loaded 3 charges 44.5, 45.0 and 45.5, five rounds each to get a starting point.

I shot them at 9:30 am and the temp was 58. I wanted to test the results again. So, I loaded up 15 more of the same charges and shot them again at 5pm. The temp was 84.

The resulting velocities showed a 100fps increase from the morning to evening shots with all powder charges. Nothing else about the brass or reloading process changed. The rounds went from being pressure safe to leaving slight extractor marks for the top load, 45.5.

I do not know if 100 fps differences are normal for temp stable powders, but it rather surprised me.

Has anyone else had this experience with this powder?

 

[Blake C]

Definitely not normal. Maybe the scale doesn't work right

 

[NWBLKTAIL]

Hmm I’ve shot it in those temps and never noticed velocity swings like that, like a few hundred rounds worth

 

[hoooogan]

I just did two temp tests with 6.5CM. 0-100 degrees was 15fps spread with ok SD, follow up in another session tested different load at 0-75 was 19fps with better SD and another load at 0-75 at 15fps ok SD. 5 shots a piece.

I second the scale being the issue. What are you using for a scale and have you confirmed consistency throughout your loading session and even between sessions?

 

[alexnelon]

Scale/measuring problem or your chronograph is lying.

You’re not using a photo sensor chronograph are you?

 

[TravOC]

I had this same problem with h1000 actually which is a pretty well known temp stable powder. I was using a relatively cheap scale. An entry level RCBS scale that was over 10 years old. Bought a nicer OHAUS scale to replace it cuz I had a feeling that was the issue. Never had any problems since!

Also comparing weighed charges with the old RCBS was astounding, the RCBS could be up to a full grain off...

 

[Torque]

I am using a True Ballstics radar chrono which has always been accurate.

I don't think it can be the chrono because there were pressure signs in the second batch that were not present in the first. Logically, I think my chrono wasn't lying.

I am using a RCBS Chargemaster 1500 as a scale. I calibrate it fully before every use, without fail.

I have confirmed the loads vs. a balance scale in the past and it has always been accurate. I will check again to make sure nothing has changed.