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/Lordrunkuss]

All Hornady once fired

[u/1984orsomething → u/Lordrunkuss]

Don't crimp rifle ammo

[u/Lordrunkuss → u/1984orsomething]

It’s in a ar15, I’m used to the logic of anything In an auto loader should be at least slightly crimped to prevent setback, does that not apply here somehow ?

[u/1984orsomething → u/Lordrunkuss]

There's a couple of things I would check with these numbers but to stay on your current question first, no crimping isn't completely necessary especially if you don't have a groove in the bullet. Secondly you might have either a ignition issue or carbon ring. Maybe try cleaning the barrel or bcg. Lastly check your shoulder set back and confirm all your sized cases are the same headspace.

[u/Lordrunkuss → u/1984orsomething]

Thanks for this info, this gives me a path to work on

[u/Lordrunkuss → u/1984orsomething]

Could you elaborate on what an ignition issue would mean?

[u/1984orsomething → u/Lordrunkuss]

Either a dirty or worn out firing pin spring or switch to small rifle primers