Hornady 6.5 Grendel Brass, Hornady 123gr A-Max, CCI 450 and IMR 8208-XB, 24" barrel

[dgp1000]

Byron, What COL did you use? What manufacture and length of barrel? I'm working on a 24" LW chambered for 6.5 CSS so that throws in a bit of a wild card.

I've now built 11 sets of 10 rounds with Hornady Brass, CCI-450 primers, IMR 8208-XBR and Hornady A-Max 123gr bullets ranging from 27.8 all the way up to 28.8.

Do you think it's worth going any higher? 28.9...29.0? What with the case separation that txgunner00 and davidj reported, am I tempting fate?! At 28.8 the cases look pretty much maxed out with a COL of 2.260".

txgunner00, What barrel/caliber(grendel/CSS/etc) configuration are you running a COL of 2.265" with? Do you think this COL should run fine in an SAOD 24" barrel as detailed here?

Thanks to all for the fantastic info. I hope to report back after this weekend with some stats on how my new shooter performs.

[txgunner00]

Satern barrel, grendel chamber. Can't say for sure on the COL as I'm not familiar with the SAOD. I would think you should be OK with the 123 amax at 2.260. Cycle a few rounds through the chamber before firing to make sure they aren't sticking into the lands.

[dgp1000]

Satern barrel, grendel chamber. Can't say for sure on the COL as I'm not familiar with the SAOD. I would think you should be OK with the 123 amax at 2.260. Cycle a few rounds through the chamber before firing to make sure they aren't sticking into the lands.

Using a COL of 2.260 cycles fine, no signs of bullets being driven in to the lands.

Thanks

[dgp1000]

Finally got to spend some time at the range over the weekend and work on a load for my 24" LW barrel. Here's how she did.

All results were using Hornady brass (first load), CCI 450, IMR 8208-XBR and Hornady A-Max 123gr bullets. COL was 2.260". 100 yards. Only shot three rounds per load with 11 loads total. I was looking for consistent velocities.

27.8gr 2552, 2568, 2543
27.9gr 2535, 2566, 2543
28.0gr 2561, 2550, 2544
28.1gr 2537, 2561, 2600
28.2gr 2567, 2560, 2558
28.3gr 2578, 2574, 2570
28.4gr 2583, 2567, 2582
28.5gr 2613, 2580, 2617
28.6gr 2584, 2585, 2581
28.7gr 2603, 2590, 2618
28.8gr 2638, 2678, 2582

At 100 yards all of these grouped outstandingly.

The most consistent load as far as Velocity goes seems to be 28.6gr.

Quite a jump in Velocity when I went up to 28.8gr.

No signs of over pressure on any of the brass.

Could you guys give me a hand in deciphering the above? Is it worth trying an even hotter load?

Thanks,
David.

[rasp65]

You would be better off to raise the size of your sample to at least 10 round of each to get a more accurate picture of the consistency of the load.

[dgp1000]

I actually had ten of each with me but was running out of time and only managed to shoot three of each.

Was hoping with a bit of help we might be able to narrow down to four or five sets for my next trip.

What do you think? Need more data or can I narrow down some what?

[killerb]

I have an 18" satern liberty barrel but using a similar load with very good accuracy at 100 yds. Shot 20 rounds in the bullseye this past weekend that i could cover with a 50 cent piece.
28 grains XBR 8208
Hornady 120 grain amax bullets
CCI small magnum magnum primers
Hornady brass
COL .2235

[LRRPF52]

Have you guys looked at the Optimum Barrel Times for your barrel lengths from this table: http://the-long-family.com/OBT%20Table.pdf

It lists the OBT's for a 24" at (all numbers in mS):

0.8160
0.8948
1.0221
1.1016
1.2282
1.3084
1.4343

These are the Optimum Times on the barrel where the shock wave is furthest from the muzzle, meaning a more stable muzzle geometry and more consistent muzzle to resting position, which are the best times for the projectile to leave the muzzle. The shock wave travels from the chamber upon detonation at over 28,000fps back and forth from chamber to muzzle to chamber to muzzle, and there seems to be independently-verified confirmation of this behavior when used to time the exit of projectiles and the correlation to accuracy.

I'm not sure which ones are safe in the Grendel with the 123gr, as they will have to be plugged into QL to find that out theoretically. If you drive the other data based on the barrel time feature, you'll see the pressures, velocities, and charge weights populated into the fields as normal. It can give you your accuracy node areas to play with right off the bat.

[midnight]

Thanks all you guys for the good info. I'll be loading 8208 in Hornady brass with 123gr A-maxes & 123gr. Lapua Scenars. They'll be fired in a SAOD 24in 1-8 barrel. I took note of the OALs suggested. We'll see what max OAL is and work back from there. I'll post accuracy & velocities as soon as we get rid of some of this snow. My range is down a really steep hill and getting back out can be a real bear. I think I have some Nosler Ballistic tips I'll throw in the mix.

Bob

[dgp1000]

I'm going to go ahead and make 4 sets of 20 each using the same data as in my last post with charges as follows:

20 x 28.7g
20 x 28.8g
20 x 28.9g
20 x 29.0g

Has anybody else pushed the 6.5 grendel up to 29.0g of XBR?

I'll get results posted as soon as possible. Wish me luck!