Bullet jump 123 gr. SST in 6.5 Grendel

Hey Guys - doing some load development for my sons 6.5 Grendel (Howa Mini) and until now we have just been seating them all to Saami specs 2.250 COAL.
However, we measured the "lands" today with our comparator (to the best of our ability) and it would seem at 2.250 we are around 0.050 off the lands.
We do have a bit more room in the magazine and loading a dummy round we can squeeze 2.290 into the mag and that would put us right on 0.010 off the lands.

New rifle and we have only done our first batch of testing and so far it's been shooting ok with the best load just under an inch with my young fella shooting.
Questions - we are about to load up some more to test / verify so would you stick to the Saami COAL 2.250 and adjust seating depth later or run this test batch closer to the lands ?

The bullet testing is the 123 gr. SST over various charges of ADI 8208.
Thanks in advance.

"just under inch" leave it alone......

First of all find the best load at the length you are using now and then try varying the OAL and see if there is any improvement. I run the same bullet powder combo in my Grendel (Sako) at 2.297" (58.36mm)

Do some of both in the one batch and let us know the outcome....

I am working on a similar question myself... so your effort and results may be of benefit to me..

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Originally Posted by Mathias

First of all find the best load at the length you are using now and then try varying the OAL and see if there is any improvement. I run the same bullet powder combo in my Grendel (Sako) at 2.297" (58.36mm)

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Thanks - do you know how far off the lands you are at that length ?

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Originally Posted by Pete_D

Thanks - do you know how far off the lands you are at that length ?

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Sorry don't have it listed in my load book. This length works best in my mag too. There are a few different specs for the Grendel chamber, mine will be different to yours.

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Originally Posted by Mathias

Sorry don't have it listed in my load book. This length works best in my mag too. There are a few different specs for the Grendel chamber, mine will be different to yours.

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No worries - out of interest what's your powder charge with 8208 - there seems to be quite a bit of variation amongst published data for 123 gr. bullets.

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Originally Posted by Pete_D

No worries - out of interest what's your powder charge with 8208 - there seems to be quite a bit of variation amongst published data for 123 gr. bullets.

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The sweet spot it seems, with the Grendel and this powder is in the 28-28.5gr with 123gr Hornady's. I'm at 28.2 with Lapua brass and a 17" barrel for an average of 2422fps. I use a CCI BR4 primer.

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Originally Posted by Mathias

The sweet spot it seems, with the Grendel and this powder is in the 28-28.5gr with 123gr Hornady's. I'm at 28.2 with Lapua brass and a 17" barrel for an average of 2422fps. I use a CCI BR4 primer.

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I run a very similar cartridge in that its a 6.5mm and holds around the same powder charges.
Mine has 24 inch barrel. I get slightly more velocity (150fps) than you with 27.5gns 8208, its my most used rifle by a long long way. Had a Factory Grendel bolt action been available at the time I would have gone that way.

FWIW 123gn Eld-M's loose their accuracy past 700m but pretty good till then, Laupua 123's are good to 900-1000m (shooting steel) and my self imposed limit on game is 300 or less (this seems to be about normal for 6.5 shooting 120-123gns projectiles around these velocities as my good mates Grendel is very similar / same

Thanks guys - I'm figuring the 123 Gr. SST is designed as a hunting round, so assuming Hornady deigned them to not be too fussy on seating close to the lands.
I'll load next batch all at standard COAL 2.250 but test up to 28.3 grain of 8208. So far we have been loading mild only up to 27.0.
Cheers for the input.

My Grendel has a real tight chamber.
Factory 123gn SSTs are seated into the rifling.

I've seated my hand loads back more (0.25mm from the lands) and am now using 30.5gn CFE223.
27.5gn CFE was more a little bit more accurate, but glacially slow.

Well I've just loaded up the rounds tonight from 26.8gr - 28.3 of 8208 in 0.3 gr increments (max load listed by ADI is 28.5) and as noted by ADI 28.3 would appear to be slightly compressed. Just a tiny bit of crunching as I seated the bullet and after re-checking overall length, the bullet seemed to creep back 2-3 thou or so. I ran them back through the seating die to make sure they were fully seated. I've never loaded compressed loads before so just wondered is there anything else I need to be aware off ? Cheers

I just loaded to mag length in mine 0.005 of mag length
And done ocw testing there

My pet load though was a 100gn varminter Sierra which is a
Short stubby bullet and i had to load that at 2.200 to clear the lans
I was running that with 32.3 gn of cfe223
In lapua brass with cci br4 primer
Shooting .4 inch groups (factory howa mini) apart from a trigger job and a shorten to 20in and dpt

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Originally Posted by dogmatix

My Grendel has a real tight chamber.
Factory 123gn SSTs are seated into the rifling.

I've seated my hand loads back more (0.25mm from the lands) and am now using 30.5gn CFE223.
27.5gn CFE was more a little bit more accurate, but glacially slow.

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Your chamber might be the original stepped throat (compound) design that Alexander Arms used when designing this round. Some later designs of throat allow a bit more room for the 123gr. I used CFE223 for a start and ran into pressure before any decent velocity, so I took on board comments from other Grendel users and switched to 8208 and picked up improved accuracy & speed for less pressure.

That makes sense, as it’s an Alex Arms barrel.

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Originally Posted by dogmatix

That makes sense, as it’s an Alex Arms barrel.

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Original development was around the 108gr Scenar. The 123gr came along later, hence the move away from the compound throat by some barrel manufacturers. Mines a 264 LBC variant.

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