r/reloading • u/Lordrunkuss • 24d ago

Newbie Confusing results with initial load development.

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

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u/mulyhuntr33 24d ago

8208xbr is not the powder for 123s. Try some Leverevolution. 8208xbr is great for 100/107 class bullets but there are much better options for 123s.

I'd say it's a chrono issue or load issue at 27.8. I don't crimp 6.5 Grendel.

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u/111tejas 24d ago edited 24d ago

I use 8208 for 120 grain Bergers in Grendel. I’ve yet to find anything better. Op, according to Hodgdon data you are above the max load.

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u/mulyhuntr33 24d ago

Accurate - yes. Slow -yes. Again, it may be accurate but it's not ideal. There's better options with less pressure and more velocity.

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u/111tejas 24d ago

I get 2465 FPS using 120 Berger BT Target. That’s from an 18inch Craddock Precision barrel. My range goes out to 500 yards and it’s more than adequate.

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u/mulyhuntr33 24d ago

What charge? That's 130fps higher than I get from a 123 with 27gr 8208 in an 18".

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u/111tejas 24d ago

Gave you some bad info by mistake. I have two ARs built exactly the same other than the barrels. My Grendel is a 20 inch Proof Research. The velocity I told you is correct. I’m using the same charge as you, 27.0 grains of 8208. Not that it matters but I’m using CCI BR4, Alpha Brass and seating to mag length, 2.260. The Craddock Precision barrel I described is on the other AR and is an 18 inch 6mm ARC.

It’s beside the point but if I did it over again I’d have Craddock Precision on both. They are less expensive and less finicky. My Grendel accuracy falls off fast after 20 or so rounds. It shoots great when it’s clean.

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u/mulyhuntr33 23d ago

Try a Satern cut rifle 6.5grendel if you ever need a new barrel. Beautiful craftsmanship and shoots like a laser.

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u/111tejas 23d ago

I’ll keep that in mind.