My barrel changed its' mind?

[Chris Butler]

After going through the break in process with my 111 Savage Long Range Hunter 300WM I tested a bunch of different factory ammo with different bullets.
I settled on 200gr Eld-X. The worst 5rd group I shot was a .738
Fast forward about 220rds through the barrel and I'm no longer getting groups from the Eld-X's. In fact I'm not even getting a consistent POI. Like I suddenly forgot how to shoot a rifle.
I clean it, check the bedding, action bolt torque, shoot different rifles first, dry fire, etc.....
I tried some of the other ammo I had left over. Now the rifle is grouping 210 VLD's and and 215 Hybrid's. It groups Hybrid's best.
I ordered enough factory 215 Hybrid's for what's left of elk season.
Today I shot a cold bore zero. Dialed the correction then confirmed at 200 and 300yds.
I ran 10rds through the Magnetospeed, entered the data in my phone and confirmed DOPE out to 1109yds.
Anyone else have a barrel change bullet preference after putting a couple of hundred rounds through it?
FTR - I have enough Norma brass for the life of the barrel and a couple of boxes of 215 Hybrids ordered.

 

[boltfluter]

Chris,

That's a new one on me. Since this is a factory barrel, the break in period may make a much bigger difference in bore condition versus a custom barrel that is lapped during production. Purely speculation on my part. Looking forward to the other replies.

Paul

 

[FURMAN]

In my experience somewhere around 100-150 rounds speeds of a known load increase and I have to back the charge off to get the load to shoot again. It usually takes .5-1 grain less to get the same velocity which is where the bullet wants to shoot. Sometimes once fired brass vs new will cause the same issue.

 

[KMart]

Back about 8-10 years ago I bought a Savage VLP in 308. Most everything I read back then, indicated that it would take about 200 rounds down the barrel before the barrel settled down. Sure enough, about 200 rounds and the barrel stopped copper fouling badly and started to shoot differently.
At this point, you will need to go back through your factory cartridge selection for the best shooting one or reload for it.

 

[Prose]

Carbon ring?

 

[dkhunt14]

Different lot of bullets? Matt

 

[Texas10]

Throat erosion?

Or less likely, but i have to ask, have you developed a flinch? 300 WM in a light rifle

 

[ckaberna]

Same scope?

 

[BIG D]

Sounds like the bullets are jumping more than they like. 220 rounds I’d guess .005-.010 throat erosion would cause that.