280 AI weird groups??

[Texis]

Getting strange groups, 2 touching.. next shot 1/2"-1" away. Repeat the best load, .350" and then get a 1.5" group.

Background:
I built the rifle, Remage 700 with a 22" 1:8 twist Criterion barrel. HS stock, Trigger Tech, NF SHV 5.5x20. Scope mounts are tight. I've owned this NF for years, it has been rock solid.

To start, I love the round, smooth, no pressure signs pushing 160gr AB or LRX at 2900 with 58.7 gr 4831SC. COAL at SAAMI.

I'm an experienced hand loader, I've tried moving the COAL in .010 increments in both directions, shoots the best at SAAMI lenght. I've tried working the load in 1/10gr increments, 58.7gr works the best.

I use RCBS dies and Whidden bushings and mandrel, bump the shoulder back .004-005 (it's a hunting rifle) Redding scales. I have been seeing 9-15 SDs, all good there.

I keep round counts, currently at 143. My next move is give the barrel a deep cleaning then lead it with dozen rounds or so, and try again!! This is about the point I typically deep clean, but it hasn't degraded in accuracy.. it's shot like this since I started.
Any ideas are appreciated.

 

[nwmnbowhunter]

Two together and one out has meant one of two things to me...

1. Need to go up in powder charge....flirting with next node.

2. Ignition issues and inconsistent firing pin fall.

 

[Texis]

Pin and spring are new, primers all look the same.. hitting deep and hard. I did go back with the higher rate spring… could that be a negative?
Flirting with the next node makes sense, or maybe moving up and out of a node. I have considered graph plotting a ladder to see where the nodes fall.

 

[nwmnbowhunter]

Pin and spring are new, primers all look the same.. hitting deep and hard. I did go back with the higher rate spring… could that be a negative?
Flirting with the next node makes sense, or maybe moving up and out of a node. I have considered graph plotting a ladder to see where the nodes fall.

Check overall pin fall

I had one that was only .220 and it wasn't enough to have consistent ignition.

 

[Texis]

Shot this today, all the same load but 3 different primers. CCI BR2, REM 9-1/2M, Fed 210M.

 

[Texis]

All deep, Minor flattening but no ejector marks or sticky bolt.

 

[Texis]

Btw.. Peterson brass, on the second firing.

 

[Koda_]

To start, I love the round, smooth, no pressure signs pushing 160gr AB or LRX at 2900 with 58.7 gr 4831SC. COAL at SAAMI.

So which bullet is walking to 1.5moa?
Are you shooting the monos before the cup and core or vise versa?
Are you using these bullets interchangeably?

 

[Texis]

I've tried both. Both seem to behave the same, inconsistent. Yes.. I am using them interchangeably, but never in the same set. I've tried monos one day, ABs the next, then try the monos again a few days later.
Could the differences in alloys be causing it?

 

[Brathany]

If it's a light contour barrel then that's the norm. Heat affects the groups after two consecutive shots.

 

[Texis]

Heavy, varmint profile. 3 shots, wait 10 minutes. I try to keep it a consistent temp. But, your right sporter profiles start throwing rounds quickly.

 

[manitou]

I have a rifle (280ai also) that does that. Driving me nuts for two years.
I have yet to figure it out... and I have tried everything but hiring a magician.

 

[Brathany]

Heavy, varmint profile. 3 shots, wait 10 minutes. I try to keep it a consistent temp. But, your right sporter profiles start throwing rounds quickly.

Shoot 10 round group and see what happens. Criterion heavies have been fantastic shooters for me, up to 20rnd groups.

 

[cajun]

Is the recoil lug bedded?