280 AI weird groups??

[Teekerguy]

My hunting distance is 550 on game, out to 1,000 on hogs. 2 firings on the brass, the behavior hasn't changed.
Temp stable powder is mandatory, I shoot / practice in the heat and hunt in the cold. I've seen enough exploding ELDXs to stay away.. no hate, some people love them but I don't care for the terminal behavior
I did hunt with VLDs for a couple of years with my 708, they shoot very well. I prefer a pass through with blood trail.
I like a Barnes, BCs are low and the throat is too short for LRX.
My pickiness about terminal performance has me in a pickle
I guess the main dilemma is " another $400 on components… or another barrel?"

If 550 on game is your distance I'd go with the slower node that's more accurate. I know it's not the speed you want but at the end of the day that if that's what that gun likes then that's what it likes. My 280ai also is laser beam with the 162 eldx but it's also slow as well around 2740 with H4831 with a 22" bbl. It hammers steal at 600 no problem. But I totally understand where you come from wanting the more FPS. Another thing to consider try is Dan newberrys OCW tray . You just might be a little bit out of the sweet sport for that charge

 

[Texis]

I think I will continue experimenting with on-hand stuff. I have plenty of 6.6 StaBAL, H1000, 4831SC, 140 & 168 VLDs, 150 NABs, misc Barnes and 150 ELDX… "if" it shoots with any of it.. that would mean the barrel is fine, just picky.
If nothing shoots… I'll spring for a barrel.
My 708 loves the StaBAL.. pushed the 140VLD at 2850 and ragged holes at .010 off jam. (26" barrel)
Stay tuned

 

[xr650rRider]

I have a 280AI made by Alamo Precision 1:9 twist. Never got 160 grain AB's to shoot well. It shot < 1" with 150 Nosler BT's, shot well with 175 LR Accubonds. Throated it for the 175 LRAB with pressure ring just above the neck junction and it consistently shoots 0.5" 5 shot groups. 60.5 H-1000, 2750 fps average.

 

[AussieWriter]

UPDATE:
Still well below my expectations. I was able to use the rifle and take a mule deer and spike whitetail, the groups were "good enough" for that BUT this rifle refuses to shoot well consistently.
The rifle still throws weird groups beyond 2-3 shots that are not acceptable and often 2".
After 200+ rounds, dozens of test trips to my range, trying 4831SC & H1000.. charge ladders, jump testing, bedding, etc, etc. I'm beginning to think the barrel has issues. I think this because it will drive tacks, BUT only going slow! Slow as in a 160gr at 2740 fps.
In starting over on testing, again, I learned it will put 5 in a 1/2" (ragged hole) but only on the slow end of the ladders. My 708 can do this … didn't build a 280AI to do what my 708 already does.
The barrel is a 22" 1:8 varmint barrel and it will hit 2900fps with the 160s without pressure. The load I hunted with ran 2900, so it has good speed.
Every time I try to speed it up, it starts spraying and double grouping. I would be satisfied with 2850. BTW the SDs are great, 10-16. Using Peterson brass and Nosler 160 Accubonds (on my 4th box attempting to tune )
My expectations are realistic, 5 shot groups in .750" or even consistently 1" will do for my hunting distances, but not going to accept 1.5". I own 2 Shilens in 308 and 708, both are capable of this. This barrel is my first from McCowen.
At this point I'm considering just ordering another Shilen vs continuing to pour money into powder and lead. At some point I have to ask myself "how much time and money do I keep dumping into components?"
What is the definition of insanity?

Thoughts?

I had a similar issue and found my barrel didn't like those 7 Remington powders with heavy bullets.

Try some H4350, R17, or even some 760, something in that range.

 

[slikmrc]

Sounds like you've checked all the usual problem suspects on this gun. One other thing to check would be that the guard screws have clearance and aren't causing stress in the action. You are at the point were I would try and smooth up the barrel with JB bore paste. I'd also run some Tubbs Final Finish lapping bullets through it. Depending on how rough the barrel looks would determine if I'd use the throat maintenance kit or use the full 50 lapping bullets. Had good results on several barrels using these bullets. StaBall 6.5 has worked good for me on cases in the 06 range of capacity. Case fill can be an issue seeing how dense 6.5 is. seems to like 90% or more case fill for good ES.