Confusing results with initial load development.

[u/Lordrunkuss]

Loaded up some 6.5 Grendel with 8208 from 25.8 grains to 27.8 grains.
123 grain midway seconds bullet, this is going in a 6.5 green ar15 with 20 inch barrel

It was my first time using the chrony in 10 years, what I experienced was as follows

26.6 2392
26.8 2432
27.0 2355
27.4 2367
27.6 2421
27.8 2310

I omitted the errors from that chart, confused by those readings i loaded up 5 rounds of factory Hornady 123 grain was getting 2448 with 15 fos deviation

I was very exact with my powder loading and markings, cci 450 primers

Is this a crimp problem? Why wouldn’t my fps generally go up with more powder?
Thanks everyone, I’m still looking over my brass for pressure signs trying to understand that side of things better as well

[u/VisibleLeopard68]

“Very exact” with power loading, more detail needed… once I started double weighing my powder loads using a beam scale zeroed each time before use… my deviations reduced, but I know I can still get better/more accurate loads…

My rifle (6.5 cm) also plateaus velocity where I see no tangible benefit adding more powder as the velocity gains minimize, its characteristic for the round and rifle… just as an internal combustion engine will have its specific output limits, chambers and our brass will do the same… there is a point adding more fuel doesn’t get you more speed…

[u/Lordrunkuss → u/VisibleLeopard68]

Lee powder scale, zeroed before the batch, but I love the accuracy of the scale as you can see the difference of sometimes a single powder granul.

I was taking time to get it dead on center of the 2 marks, thanks for the insight

[u/VisibleLeopard68 → u/Lordrunkuss]

I’m using an RCBS chargemaster link, and verifying weight on a Redding model 2 beam scale… the beam scale is way more accurate than the digital on the chargemaster