Looking for some thoughts on this before I take the action out of the stock….
• Rifle: Berretta .280, Barrel 22”, 1:10
• Bullet: Hornady 162gr SST
• Case: Norma
• Primer: CCI-BR2
• Powder: H4831SC

Started load development on the 162gr SST for a hunt in May. Load profile…
• Starting Load 51gr
• Stop Load 54.5gr
• .3 powder increase at each step
• Never reach any pressure signs

Issue: From 51gr to 52.8gr bullets strike in the relative center of target. Groups are nothing brag about.
From 53.1gr to 54.5gr bullets start working their way down the target and slightly to the right. Condition repeated on a subsequent sequence I fired to retest.
I’ve never seen this during a load workup and no idea where to start looking for the problem. Groups are not tight at all....

Thoughts ?

Thoughts...

Is everything tight? Scope rings, bases, action screws, etc?

Have you used that bullet before? It seems to be a favorite around here, but I tried it in a 7-08 and got terrible groups with many different load combinations.

Is the barrel free-floated?

Trusted scope?

- Scope rings and base (picatinny rail) are solid - torqued the correct amount.
- Barrel is free-floated
- I am new to the 162gr SST, not used it before... but have used the 140gr SST
- The scope is new - Athlon, during sight-in it worked as expected dialing up/down, left/right.... used it at 50yrds, 100yrds and 200yrds..

It might be that 1:10 twist is too slow for the heavier bullets. Maybe your bullets are tumbling. My 7rem mag is 1:9.5 and starts to struggle with 162’s. I had a similar problem on a 1:10 twist 243 wssm with 103 eld-x’s. Took it over to 25 yard range and there it was a perfect outline of my bullet.

It might be SST’s. Some rifles just don’t like them. Were the 140’s SST’s? Did they group well?

Don't believe Hornady makes a 140gr 7mm SST. You mean 139gr, perhaps?

Did the wind pick up? A wind from 7-11 o'clock on a clock dial will push a bullet low right.

I'd check every screw and if everything was tight I'd keep going until I got pressure...there might be a harmonic that is causing a low right and with additional powder, I've seen some come out of it. Meaning I've seen bullets impact lower than others as I was increasing charges for a ladder test but most of the time within a few more charge increases it will come out of it and impact higher than the previous or at the top of the previously shot bullets.

Different charges can go pretty well in different directions. Up , down and side to side.

I wouldn't be worried about the POI moving up or down as the charge changed, but not getting good groups on any of the loads would definitely be concerning. As others have mentioned, you may not be able to run that bullet in that barrel. If I really wanted to stick with that bullet, I think I would pick the load that grouped the best and play with the seating depth and see if that helped.

I’m putting my money on a 10 twist barrel being the issue. If you want to stick with the SST try a 154. If you want to stay in the 160 class try a 160 Sierra GameKing.

Actually, it’s kind of a coincidence this was posted. I currently have two ladder tests loaded for my 7mm Rem. 154 grn SST’s and 162 grn SST’s. I tried to load eld-x’s175 grn with no real luck in my 1:9.5 twist barrel. So I’m working back down the spectrum. I’ll post results if I end up with any decent groups. I’m using RL22 starting near max from the Hornady load book and working down.

My unsatisfactory experience with the 162 SST was with a 1:9.5 barrel. Been poking around on the internet and there seems to be some consensus that a faster twist is required. I believe Fireman JG is a big fan of this bullet. It might be good to get his input. (No offense, Smokey Bear. I think you have the right answer.)

Not speaking for Jason but the SST is not an A-Max or ELD. They have never been known for accuracy although I wouldn’t call them inaccurate.

The SST is a shorter bullet than the A-Max or ELD as well. It should stabilize fine in a 9.5, I don’t know about a 10 though.

My .280 Ackley has a 1:10 barrel. I run 160 Accubonds and use 4831SC. .5 inch groups all day long. When you increase the speed of the bullet the trajectory is going to be affected some. Fireman and Chad have good info regarding such. A bunch of others here too.
I developed my load myself and didn't care about going as fast as I could. Found what worked and stuck with it. The elk I have taken with it didn't seem to care how fast the bullet was that hit them.

I might try the 160 Accubonds if I strike out on the ladder tests. Curious: what velocity are you pushing them at? My first priority is primarily accuracy. Velocity is not as important to me as long as it’s within reason.

I've loaded a shot a metric ton of 162 A-Max and 162 ELD-X in 7mm-08, 7mm-08 A.I., and .280 A.I.

The twists have been 1:8.7, and 1:9. Those twist rates and a 162 just go together.

After reading screws tight, barrel free floated, appropriate components, I think the 1:10 twist may be the problem. The only way to (kind of) overcome lack of twist rate is a stout powder charge. That's not a real fix, but it can make things work, if you're staying inside 500 yards.

I've also loaded 154 SST in the 1:9 7mm-08 and they stacked inside 1 inch at 300 yards. So, the 6mm and 7mm SST bullets have been made to shoot tight for me.

I’ve got a box of the 154 SST I will send you to try.

I was never able to get the .280 chronographed. I use 4831SC. It is now an Ackley. I was able to get 55 grains in the .280. More than 57 in the Ackley. The Ackley was chronoed but I can't recall just what we got. I will do some more looking to see what I was doing with the standard round if you would like to have that.

g

Probably 2900 fps minimum in the A.I.

just do what i do

sell it


start over

I have it somewhere, but I think you are correct Jason. Waiting to see what the 7-08 Ackley does. Got the 162 ELD-x bullets shooting good now.

24" barrel, 2800-2830 fps

The 168 gr Berger Classic works in 1/10 twist and ran 2860 from my standard 280 Rem.
It’s proved itself on several elk.

19" barrel. 41 grains of 4166 (can't get any Varget)

My 17" 7mm-08 A.I. plus suppressor

162 gr at 2640 fps MV

In theory, you should be 50 fps faster.

Good! Thanks

G