Re: 6.5 Grendel OAL Issue AR-15
Thanks for all your responses. All good comments. I will expand a little. I understand measuring the ogive with the comparator, with each bullet in each gun/chamber, etc.
The significance of mentioning OAL is simply to honor the 2.260-2.265 OAL restriction of the AR magazine.
All the load data I have seen, Alex Arms data on their website, the Hornady Data on their 123, load data on the 6.5 Grendel website, etc., all give OAL of 2.245, 2.260, 2.250, 2.255. I am sure you all are familiar. I will give you one example of what I discovered, and I agree powder has no relavance here.
(After extensive load development with Nosler 100 gr BT starting at 25.5 grains of BLC-2 steping .3 grains per 5 rounds loaded I settled on 26.5gr BLC-2, giving me .375" at 100yards. I used an OAL of 2.258, just like all the data showed, and no pressure signs at all.)
So what's the problem? The problem is:
While firing this excellent load at the range I had a misfire/light hit. Waited 2 min and attempted to eject the live round. The round was hard to eject. Finally, it popped out, and the bullet was way out fo the case neck. There were land marks on the bullet as if it had been driven into the lands. The 2.258 cartridge I loaded into the chamber was compressed/jammed/slammed to about 2.220, the bullet stuck in the lands, and upon manual ejection came out of the case neck far enough to be quite noticable. I found the same to be true then with 120gr BT Noslers and Hornady 123s that I had loaded to 2.260, the maximum magazine case length. Therefore, I can not load these bullets in this AR-15 Carbine anywhere approaching magazine length, in an 18" AR Stoner .264 LBC AR barrel. That is my question. Anyone else shooting this combination experienced a problem like that?
Finally, for the technicals, here are some detailed numbers to perhaps help explain. Just for 100 BT Nosler bullet. Ogive measurement is 1.694 minus .020-.040 for "jump" to lands [although Noslers like to be "snug" to the lands], puts my fully reloaded bullet length at 2.193. The maximum measured OAL in this chamber with a Nosler 100gr BT bullet is 2.233, measured about 50 to 60 times. I can not load this bullet longer than 2.233 when all the data I read says I should be able to go to 2.25-2.26.
When I measure the Hornady/Hornady 123 bullet in my chamber, the maximum OAL is 2.240. When I load the Hornady Factory 123, OAL of 2.245 and manually eject it, I have land marks on the bullet. It is jammed into the lands, albeit only .004-.005.
Anyone experience similar problems reloading for the .264 LBC AR, that is the question. Thanks again for your interest.