280 AI weird groups??

[Texis]

Gentleman,
My other hunting rifles, 708 & 308 both with Shilen barrels will consistently print 1/2 MOA, I've printed tighter. I have attached a 400 yd target I shot with my 708 for your approval that I can shoot adequately. It measures .375.
As for tune… we are WAY past that . After 250 rounds of speed graphing for nodes, SD graphing and seating depth test and graphing and going on my 4th bullet and 3rd powder. If this were a tuning issue it would be over long ago.
"It's not a bench rest rifle"… must not have read the thread. .750-1.00 consistently is acceptable on this rifle.
I understand most are trying to be helpful, keep in mind if this was a simple issue, or I couldn't shoot I would not be posting on this forum.
Most inputs have been helpful and I appreciate them as they give me some interesting options I had not considered.

 

[Texis]

All your suggestions are getting me closer and closer. After bedding the recoil lug, checking all the tolerances, opening up some action landing areas, what I know so far.. it doesn't like 150 or 160 NABs, 160 Barnes LRX. It prefers H1000 over 4831SC and likes VLDs at .010 off jam. 60.5gr going 2756 with an SD of 16.
If I can just get it to stop throwing the first d### round… it will be a tack driver.
Fired 5 today. Overall .880". Making good progress. I have some 180 VLD coming, maybe they will finish this puzzle.

 

[Texis]

Also reduced neck tension by .002 BTW.

 

[Mike Matteson]

In reading back from the start of this. You have a 22" barrel which generally doesn't work as well with slower burning powders. I would suggest H 4350, and Fed 210M or Fed 210. You might step up to Fed 215 primers being a shorter barrel. You will have to work up your loads again. Being H4350 is a faster powder burn rate. I nornally don't use Fed 215 primers, but I use 26"+ barrel lengths.
I did see mention earlier about annealing the neck and part of the shoulder. That should be done after each firing. That set up better consistence tension with each case, If you haven't done that before, you'll need to read up on it. Bumping the shoulder back only .002 to .003. Check your case lenght too. A few .000th can create problems too. Finally I don't see where you using a mandrel to set you neck tension, nor straighten the neck out. Or are you cutting your necks for thickness with new cases unfired.
I may have missed it, but after cleaning your barrel are you using a fauling shot to start with. Then wait for the barrel to cool off completely. So you have a cold bore shot to start your group. It a must for me to be able to place a shot where it's aim on a cold bore shot.

 

[Texis]

Thanks for the productive inputs. I have wanted to add 4350 to the list. I did notice listed velocities are lower with 4350, so it was last on the list.. but the temp stability is the best. I'm going to try it, as it's fantastic powder.
I do use mandrels, Century 21is great, also use Whidden bushings for measurements. I reduced tension by .002 on the most recent test. The last test was set up at .001-.001.5 (depending on spring back).
I am not cutting the neck OD, have to draw the line somewhere lol. The AI case has yet to reach max SAAMI length, hasn't really grown so I haven't had to trim yet. I had heard this about AI cartridges / brass.
I love 26" barrels, my other rifles have them, free speed! I wanted the 22" on this one for convenience of carrying and storage while hunting. 22" + 4" Apollo brake and I'm still fighting gun cases on the 4 wheeler. 26" + 4" brake wasn't working for me in the field.
I did tightened up on the shoulder bump to .002 on the most recent loads.
As I increase round count on my best loads now, it's starting to look more like a cold bore issue, throwing the first round high and to the left by .500-.750. Currently researching this.

Thanks

 

[Texis]

Sorry I missed the question, yes I foul with 10-12 rounds after cleaning, before shooting for accuracy. Currently I'm cleaning between 110-130 rounds.