Rifle Accuracy Issues

[blazin_saddles_lv]

I was hoping to get some ideas on what could be causing accuracy issues with my rifle. It is a Nosler M48 Liberty in 28 Nosler. In the past, I've shot 3/4? groups using factory Nosler ammo. I had it at the range over the last couple days and it would shoot on flyer out of every three or so. The flyer would be 3 to 4 inches away at 200 yards from the group. No apparent pattern. The barrel was given time to cool between shots and didn't feel hot to the touch. It was cold outside, maybe 35 degrees. I also put it on a lead sled and had the same issue which in my mind rules out operator error.
It's been 4 or 5 months since I last had it out and the only change I can think of recently made was a scope upgrade. I went with a Ziess V4. The rings have been lapped and everything seemed tight. I was also adjusting the side focus and wasn?t noticing any problems with parallax movement. It shot well with this scope last time out.
I removed and replaced the bottom assembly to make sure it wasn?t loose, over tightened, or installed incorrectly. I also ran a receipt down the barrel channel and didn't find any contact with the barrel.
My only thoughts were maybe temp sensitive ammo or even a problem inside the scope? Any ideas on what could be the issue?

 

[Hunt_the_West]

Check for a carbon ring build up near the throat. My 28, although not a nosler rifle or factory ammo, requires pretty regular cleaning to keep it shooting well. More so than any other rifle I own.

 

[blazin_saddles_lv]

Thank you. I'm actually in the process of giving it a thorough cleaning now and will be sure to clean the throat. I've read online that some rifles shoot better with what I would consider a heavily fouled barrel. My barrel had probably 20 to 30 rounds through it since the last cleaning.

 

[Cahunter805]

Definitely keep the carbon cleaned out. Give the bore a scrub with JB bore paste or Iosso paste and see what happens. If not a carbon issue then I'd swap scopes and see what happens.

 

[Lhedrick1]

I would think a dirty barrel would cause poor accuracy altogether, not just a flyer every now and then. I would go back to whatever changed in between 3/4" groups and what you are experiencing now. If you removed the gun from the stock at all, you may want to make sure it's fastened tight. If it's a wood stock I suppose it could be climate related (going from possible humid gun safe @ 70 degrees to 35 degrees ad dry) but that seems like a FAR stretch.

I've had 2 similar experiences as you but both were after I free floated or glass bedded the rifles. In both cases, the rifles actually needed a pressure point. So by free floating the barrel, it started throwing shots.

 

[Captain_coues]

Maybe add a pressure point. Also have someone else shoot a few groups to see if it really is the gun. I remember a series of three groups I shot out of my 300 WBY that was the same thing. I shot three shots in each group that were the best of my life and on the fourth, it was 1.5? off. I figured out it was me throwing the shot. I could only guess seeing how good the groups were, it did something to my mind and I either rushed or flinched or something.

 

[RELH]

Before you go to the trouble of adding a pressure point, give the barrel a good cleaning with a copper removal cleaner. I have a 25-06 that will shoot 3/4 inch groups, but when the copper fouling builds up, it starts to open up and will throw a flyer also.
20-30 rounds is enough to cause a copper fouling in the barrel.

RELH