280 AI weird groups??

[Montana'eer]

I have a fairly new .280AI. 700 trued action mated to a Brux barrel, heavy contour and in a McMillan Rem hunter stock. I had the same problem. I had found a couple powders that worked using Peterson brass and Federal TA 155 bullets. However same as you- 2 touching one flyer. At about the sane round count as you- I cleaned the barrel down to zero (completely) and took it to my gunsmith. He scoped it and about 3/4 towards the muzzle end there was a mar down the rifling about 3"-4" in length. We sent it back to Brux and apparently they failed to do the final lapping. Got it back and it's better- but not bug hole better. Sub moa at 100yds.

Check your barrel would be my advice.

 

[Jeremy Henderson]

I had the same problem with my 6BR. What I found was measuring each case I had a few that were.002 longer trimmed to the others and the flyer stopped. Hope you get it figured out.

 

[Rem81]

My 25-06ai has similar problem. First shot be the odd one. Tried all kinds of bullets and switched to hammers and problem fixed!!! Rifle only likes hammers, that's ok cause they shoot little bug holes.

 

[Texis]

Update…
I pulled the rifle apart, bedded the recoil lug and also found that the stock had some paint from the OEM slightly over the aluminum frame at the rear bed points. This was enough to keep the action from making solid contact with the frame. I removed the paint with the tip of a small sharp knife. This allows the receiver to make solid contact with the aluminum frame.
Also discovered the trigger was making very slight contact with the bottom metal.. fixed that.
I changed out the firing pin spring back to the original, removing the 18lb spring.
I believe I'm on the right path based on the first group. First shot was out (arrow). This was to be expected as the action settled in. Then fired 5 shots. The 5 shot group printed 1.100, not a great group… BUT very spread and nothing weird! It produced a nice dispersed group.
I feel like I will be able to now tune the load as it's has different harmonics properly bedded.
Very encouraged to NOT get another weird group.

 

[Texis]

BTW I decided on using the 160 ABs that were running 2900. I'll do a ladder in 1/10gr increments moving up from 58.7gr.

 

[Texis]

Gentlemen,
Thanks for all the inputs, the rifle is shooting. Deep clean, lug bedded and other bedding cleanup.
Just put 6 shots in .750" with 160 AB at 2900 and nothing weird! Certainly not bench rest and I will be validating with larger sample size groups.. I'm happy, more than capable to 500yds on the upcoming mule deer hunt if I can do my part.

Again thanks for the inputs, doubt I would have explored the bedding issues without the suggestions.

 

[memtb]

Gentlemen,
Thanks for all the inputs, the rifle is shooting. Deep clean, lug bedded and other bedding cleanup.
Just put 6 shots in .750" with 160 AB at 2900 and nothing weird! Certainly not bench rest and I will be validating with larger sample size groups.. I'm happy, more than capable to 500yds on the upcoming mule deer hunt if I can do my part.

Again thanks for the inputs, doubt I would have explored the bedding issues without the suggestions.

Good news, Congrats……love it when a plan comes together!

Now, go forth and slay deer! memtb

 

[Texis]

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?

 

[Texis]

BTW my previous 6 shots in 750" apparently was a fluke, as it wouldn't do it again!

 

[Teekerguy]

BTW my previous 6 shots in 750" apparently was a fluke, as it wouldn't do it again!

How far are you shooting for your hunting purposes?

 

[manitou]

I have a custom 280ai that hated Accubonds. It'll shoot 1/2" with 168 Berger VLDs and 7828 or re23.

Another 280 ai prefers ELDx over Accubonds, but the same brand and model rifle in .280 Rem shoots 160 NABs sub 1/2"!

7828 SSC is magic in all four .280 flavors that I shoot. Switched to re23 only because of the wide temp swings I hunt in. The 7828 is the most accurate in 160g+ bullet weights.

 

[Rflshootr]

Just a thought.......how many firing on the brass?
Have you ever annealed the necks?

 

[Texis]

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?"

 

[Josh06]

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 would try a different powder. I have a 20" 280ai and have had good luck with Ramshot Hunter and Staball 6.5 for good velocity and groups. I used 4831sc with 180 eldms and found accuracy but it was slow like you experienced.