Hornady 123SST and W748

[vaguru]

I have been frustrated trying this combo. Using PPU brass, CCI BR4 primers, and worked up to 30.0 grs W748. Tested COL out to 2.280" which had the best ES of 18 fps, at 2652.8 fps ave. Initial testing over chronograph at 50 yards shows groups ave .276". Going out to 100 yds groups maybe 2" if I'm lucky.

I have a 120 ELDM load that groups consistently 1/2 MOA at 100 yds using same case, primer and powder with different charge and COL, so I doubt the rifle is the issue.

I have also used Hornady brass with this load at factory COL of 2.245". ES was 13 fps at 2614.4 fps but groups still not what I expect.

Is the 123SST that finicky of a bullet that some barrels just won't shoot it well?

Looking for a decent load with a capable deer hunting bullet. Any other hunting bullet I should consider?

[603Country]

Groups at 50 yards are great, but grow to 2” at 100 yards? That seems odd to me. That would suggest a non-stabilizing twist, which seems unlikely. As for the bullet, it shoots quite well for me, using Lapua brass, CCI 450, and H335.

[rickt300]

The 123 gr. SST does not shoot much better in my rifle and I tried several powders. Other bullets shoot much better. Still good enough for average deer hunting. Your speed seems a bit high.

[vaguru]

603Country,
"Groups at 50 yards are great, but grow to 2” at 100 yards? That seems odd to me. That would suggest a non-stabilizing twist, which seems unlikely. As for the bullet, it shoots quite well for me, using Lapua brass, CCI 450, and H335."

What is your powder charge and COL?

[603Country]

The wife is watching a stupid show, so I went out to the workshop and got the load info. The brass is Starline, not Lapua.
H335, 123 gr SST, CCI450. The powder load is 27.2 gr of the H335. Be advised that 27.2 gr is above what my Hornady load book shows as max, so work up carefully. Other load info sources suggests a higher max load. I had no pressure signs with that load.

[CJW]

The 123SST shoots great out of 5 different Grendel barrels……..

I’ve always been able to find a great load well under max………be very careful as you approach max loads.

If a gun is shooting 1/4 MOA at 50 yards & 2 MOA at 100 yards…….something is wrong with your setup….
Scope loose, action screws loose bad bag setup etc……

Get reloading data from a solid source…………

[vaguru]

The 123SST shoots great out of 5 different Grendel barrels……..

I’ve always been able to find a great load well under max………be very careful as you approach max loads.

If a gun is shooting 1/4 MOA at 50 yards & 2 MOA at 100 yards…….something is wrong with your setup….
Scope loose, action screws loose bad bag setup etc……

Get reloading data from a solid source…………

Have loading data from reliable sources, just curious as to what 603 used. I question the new scope, may have to change out to a known good scope. 1/4 MOA at 50 yds for best 4 shots, seems like this bullet always throws one high/low.

[vaguru]

The wife is watching a stupid show, so I went out to the workshop and got the load info. The brass is Starline, not Lapua.
H335, 123 gr SST, CCI450. The powder load is 27.2 gr of the H335. Be advised that 27.2 gr is above what my Hornady load book shows as max, so work up carefully. Other load info sources suggests a higher max load. I had no pressure signs with that load.

603,

Thanks for reply, still curious as to your COL

[natebonebusta]

My bet is if he’s going strictly with the Hornady manual he’s loading a 2.245” or 2.250”.

[603Country]

Oops. I forgot to get you the COAL. Tomorrow.

[Harpoon1]

603,

Thanks for reply, still curious as to your COL

His “COL” is going to be completely irrelevant to yours! Every gun, every barrel, is a snowflake! A one off, unique! Just because his shot one combination well, has nothing to do with whether yours will or will not! Use a reliable source for data, start low and find out what “your” gun likes!

[603Country]

Here it is tomorrow. The COAL is 2.245”.

[vaguru]

603, Thanks for the info. Appreciated.

[grendelnubi]

vaguru,

I experienced similar results with SST and found that the accuracy came back at 200 yards. It could be a stability challenge as indicated by 603.

If you can, try it at longer distances and see if you experience the same and let us know.

[vaguru]

I have more test loads ready, but the temp and wind have kept them in the boxes. Looks like I may have to wait until September before they will be shot.

[vaguru]

Had a little window to test some of the loads I've been waiting to shoot yesterday. Temp down to high 70's, overcast with 3-4 mph wind. Still nothing acceptable. Shot over chrony at 50 yds. Had loads with ES of 7 fps (all loads under 30 fps), 2 shots near touching with one always out about 1 1/2", the best performer was 1/2", most 1" plus. One more test day needed for remaining loads, then forget the 123sst's and hunt with 120 eldM's, or scrap the whole idea! So far this barrel just doesn't like 123sst's with any load I've tried. Will have to get a box of factory loaded just to see what they will do, now that they are available.

[LRRPF52]

What barrel do you have?

Did you adjust your scope’s parallax or eye focus for 100yds?

[vaguru]

This upper is a 20" complete I purchased from AR15Parts.com. I was told the barrel is a Zero Delta manufactured in North Carolina. It is a 1/8 twist SS and bore scoping shows no issues, very clean looking interior.

All initial testing is done at 50 yds over a chronograph, and yes parallax is correct for distance shot, and eye focus is also set correctly. Scope is a 6-24X50 30mm side focus, mil/mil.


I have 3 test loads remaining to shoot with H335 and a reshoot of the best with W748. If I can get something close to 1/2" or less at 50 yds, and close to 1" at 100 yds consistently it would be satisfactory for deer hunting. What really is confusing is that almost every load I have tried has very solid extreme spreads, shot to shot, almost all under 30 fps, with many in the single digits. When I see ES of less than 10 fps I believe that load should shoot accurately, but that has not been the case with this bullet/upper combo, at least not yet with the 123 SST bullet.

I doubt it is a barrel issue as I have a load that shoots the Hornady 120ELDM consistently under 1/2 MOA at 100 yards using W748. Very possible this barrel just doesn't "like" this bullet. Never in 50 plus years of handloading have I not been able to get a bullet to shoot accurately in a barrel, even though it may not be at the velocity I was hoping.

I have a box of factory Hornady Custom 123 SST and a box of Hornady 123 Black on the way just for curiosity.

[603Country]

A couple of years ago, I got a rifle off of a fellow that could not get it to shoot decent groups with his favorite bullet. Lucky for me that his fav was not my fav. With my chosen bullet, that rifle shot really small groups. As for the OP’s rifle, I’d try a different powder or two. If that doesn’t help, try a different bullet. If all that fails, try a different barrel. It’s somewhat like trying to calm an angry wife or girlfriend….money needs to be spent.

[rickt300]

A couple of years ago, I got a rifle off of a fellow that could not get it to shoot decent groups with his favorite bullet. Lucky for me that his fav was not my fav. With my chosen bullet, that rifle shot really small groups. As for the OP’s rifle, I’d try a different powder or two. If that doesn’t help, try a different bullet. If all that fails, try a different barrel. It’s somewhat like trying to calm an angry wife or girlfriend….money needs to be spent.

Or wine needs to be provided.