I have a Sako L461 .223. The barrel is 1:12 twist. I went to zero the rifle and shot a locator group of Federal 55gr ball ammo (M198) @ 25yds just to make sure I was on paper. I moved out to 100 yds and got a good 1" group. I used the ball just to get close before I shot my reloads. I then switched to my hand loads: Lapua brass, remington sm rifle primer, 22.5gr Hodgdon Benchmark, behind a Nosler 60gr Partition bullet. The groups went to 3"-4". I never did get anything near 1".

Is this because of the twist rate not stabilizing the longer bullet? Or, is it the load? Both maybe?

Any help would be appreciated. I had hoped to deer hunt with the Partition bullet.

Thanks,

Kevin

First a disclaimer:
I am far from being an expert on the .223 Remington.

I have read in the past that some rifles just would not stabilize bullets over 55 grs. from a 1:12 twist barrel. A 1:10 twist was required.
So yes it is a possibility.
Could you see any evidence that the bullets weren't stabilized on the paper?

It could be that your rifle just doesn't like that powder/bullet combination.

I'm sure someone with a helluva lot more experience with this caliber than I will be along, and can help you get this sorted out.

The 60 gr Partition is not a really long bullet. I'd guess it would stabilize in a 1:12" twist, but I could also be wrong. I'm more inclined to agree with Matt G that the bullet and powder combination just doesn't work in your gun. Try another powder and see what happens.

LWD

Kevin I shoot a Rem. 1 in 12 twist I have tried 40 & 50 vmax 40 Nosler B.T.and 60gr Berger .Using Varget and Benchmark powder ,my best groups by far 1/2 inch 5 shots 100yds are with 40gr.B.T and 26.5 Benchmark . Groups open up to 1 in or so with 50 & 60 gr bullets .This was after I floated the barrel.I hope this helps.

http://data.hodgdon.com/cartridge_load.asp

I would think that most 1-14" barrels would stabilize the 60 grain Nosler, so I doubt that is your trouble. I would definately recommend a somewhat slower powder for this bullet, however. Try something like BL-C2, 4895, 4320, or similar powders.

The 55gr bullets are marginal in the 14 twist, they do better with the 12 twist. The 60 grainers need at least the 10 twist.

both rem and cz put out their heavy bbl 223 with 1 in 9 twist for the heavy bullets anything over 40 if I remember from their paperwork is heavy

That is not unusual as your on the edge with a 1x12 twist and the 60 gr. Noslers..Apparantly your intending to use that heavy bullet on coyotes or deer in which case I would try the 60 gr. Hornady HP ( a great deer bullet that expands perfectly everytime ) as its shape helps stabilize...

I would also try some othe powders..BL-C worked in my present .222 for about 2900 FPS and 1.2" groups.

I have found that even with the wrong twist as long as its not extreme that you can find a suitable load for the heavy bullets. Also you don't need the pinpoint accuracy of the varmint bullet if your hunting the larger animals, I would think 1.5 or even perhaps 2.0 would surfice for deer and coyotes etc.