My new FP10 in .223, 1/9" twist is on its way back to Savage with only 406 rounds through it.
My loads.
50g Vmax-28g W748
55g Vmax-27.5 BLC2
55g hornady sp w/cann-27gr W748
55g dogtowm SP-27g W748 & 25g H335
55g dogtown HP-27 W748 & 25g H335
These are the same loads my 2 other older FP10s shoot with zero problems at all.

I bought my new FP10 3 weeks ago to replace my 1990 FP10 that has upwards of 37K rounds through it and needless to say Im not a happy camper at this point.
After a good cleaning and taking it to the range my 1st shot tumbles......darn it!!!
I clean & shoot 1 shot at a time till I hit 30 rounds, tumbles 2x in my break in shots. Tumbles 11x out of 89 rounds that day.
Next time at the range it tumbles 22 times out of 208 shots.....Im getting more bummed as my old FP10 outshoots it! I love the accu-trigger and everything else....whats going on here I say to myself.

At 60yds its fine and all my shots are about .300",(nice small holes) soon as I shoot at 100yds I get tumblers and NO group is under 2"......Im not happy especially when both my 1990 FP10s still shoot .560-.750 at 100 yds.
My scope is a new Nikon 6-18x40sf, mounts are tight, nothing is loose.
Upone a close inspection with an eye loupe I can see at the muzzle end machine marks about 1/4" -3/8" inside the bbl. Looks like a thread pitch in easy terms. I take a dental pick with a super fine point and I feel rough edges and what seems like a groove cut along the rifling.
I call Savage and she says no problem send it back....so I do and now I wait and go back to using my high round FP10. I was excited about getting my new FP10 only to be dissappointed right from my 1st shot.