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Discussion Starter · #1 · (Edited)
A couple of questions if you please.

I've been off shooting service rifle for a while and my 6.8 (Bison 18" upper) has been getting lonely. I just helped a friend
with a build to hunt hogs with (ARP 18", rifle gas (unfortunately)) so it's time to get back on the 6.8. I managed to
get some H322, Re10X, Hornady 120SSTs and Barnes 110 TSXs locally. I loaded 25 each with the H322. With the 120SSTs I started
at 27gr and went up in .5 increments to 29. With the 110TSXs I started at 28 and went to 30 in .5 grain increments.
If either starts showing pressure signs I'll stop there when we chrono them hopefully later this week.

All new SSA brass, TULA SRM primers and no crimp (RCBS seating die).

On the Barnes 110 TSX I seated them to top of the top grove and they sure seem short. I just couldn't bring myself to leave
a grove exposed. Any issue with the loads I put together at that length or should I leave a grove exposed...??
Some of the posted data I've seen have a length of 2.30....which would have a groove above the case mouth.

The 120SSTs are at 2.285. From the data I've read these load ranges should be in the ball park. I haven't loaded up any
with Re10X.
 

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i shoot H322 and with the 110 Hornady OTM 29.5 is max for me. it gets 2670 fps out of a 20" ARP TC. and 2600ish out of my 18" Bison. I've never shot the TSX bullet with that loading.
For the 120 SST 28.0 of H322 is max. in my Bison bbl. and gets about 2430 fps out of the 18". the 120SST doesn't get much velocity with H322.
 

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1bayouboy, strongly recommend you do not shoot the 110 TSX at a short COAL as you are reducing case capacity which will result in higher chamber pressure. The ogive on the TSX doesn't reach full bore diameter until the back of the first groove (blue arrow). I shoot them at 2.410" COAL in one of my rifles and I'm still 0.050" from the lands. Loading to full-mag-length will also allow more powder capacity and higher mv with less chamber pressure. I load with H322 as it is a very stable powder over temperature changes. Found it worked best with 110gr bullets in 6.8mm. I have not used with 120 nor R10x with TSX/SST. I load long and use a drop tube to get enough H322 powder in the case but my data does not apply at mag length COALs. TSX has lower internal friction than 120 SST so loads should be significantly different.

Recommend you shoot a single charge weight velocity ladder to determine your performance boundaries. Watch velocity progress to make sure it doesn't jump or flatten. Mark impact of each bullet. If 3 in a row group inside 1 MOA, pick the middle charge weight and test there to see if that is the accuracy node. Might save you some bullets.

 

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Discussion Starter · #4 ·
Xman,
Thanks! I've never loaded Barnes grooved bullets. Two hits on the kinetic bullet puller
and re-run through the seating die and they are now all below the first groove at 2.290 COAL.
I expected higher pressure with the shorter COAL, but wasn't sure how short was too short. Thanks a ton for those pics.
The 120SSTs I seated at just below the
cannelure at about the same COAL.

I pulled the H322/110TSX load range from here and why I stopped at 30gr max.
http://personalpages.tds.net/~beebew/68spc/6.8 SPC Hand Loading Data.pdf

I see a pro chrony in the pic. Tip on that...they have a 2mm jack on the left side that is wired in parallel with the button on the front. You can get a 2mm jack and
a length of two conductor wire with a momentary switch and you'll be able to press the button on the chrono from the bench....if you don already have it set up that way.
 

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I pulled the H322/110TSX load range from here and why I stopped at 30gr max.
That really isn't validated published load data. Best to use as a guide. When reloading for max performance in the 6.8mm, just got to do your own. Brass, primer, COAL, temp, etc all make a difference.

Thanks for the tip on the chrony. I will have to make one up.
 

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I've shot 10x with the 120...... I believe you will be seeing pressure signs at 28 grs, at least I do.
Use caution when shooting 29 grs.... I don't know, maybe you can shoot that charge, my experance tells me not too.
I found a sweet spot at 27.3 - 27.5, with a reduced OAL 2.250 .....
 

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Discussion Starter · #7 ·
Thanks cag.... I revised a little and I haven't loaded anything with the 10X yet. I unloaded the 120SST loads over 28grains of H322. I also lengthened my 110TSX/H322 loads
out to about 2.285. I will also load a couple of rounds with intermediate charges...maybe .3 and .7
 
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