Any down side to a 9.4 twist vs a 10 twist in the .338? 210 TSX/TTSX and or 210 Partitions would be the bullets of choice, possibly the 185 TSX/TTSX. Got a .338-06 (non-AI) build in mind.

Don't know if the 9.4 twist will hurt but I can't see the need for it especially in a 338-06. A 1 in 10" twist will stabilize up to the 300 gr Sierra Match King in the 338 cal. I'd just stick with the standard 1 in 10" twist.

I've not had great luck with the 300gr MK in a 10" twist .338WM. I'd go 9" if it were me and I wanted to shoot long, heavy bullets...

1-10 will stabilize the 300 SMK

at 338-06 velocity?

It will at 338 Lapua AI velocities, but wont in most that are 338-06 velocities

For grins I shot a 300 gr Sierra MK from a 338 RCM recently. Twist is 1 in 10. It shot a nice tight group at 200 yds. Velocity was 2550. FYI this RCM has a slightly longer OAL of 3.050"

Even though the above test worked, I am going to be using a 1 in 9 twist barrel for a long throated 338 RCM with intentions of shooting the Berger 300 gr hybrid. I figured that is a very long bullet and why chance it?

Thanks for the input. Besides having a 338-06 build on my mind, I've run across 2, .338 barrel blanks lately, and both were 9.4 twist. I suspect one was ordered/cut with the end result being a .338 Lapua (#4 fluted, stainless, 5R, 28" unfinished). The other was at best a #3, closer to a #2 and would have just finished at 24".

According to Sierra the 300 SMK will stabilize in a 10 twist at 2400 FPS comfortably. The tech that I spoke with stated that the 300 SMk at a muzzle 2000 FPS would have a stabiblity factor 1.25

9.4 in my 338 Lapua works great with the 300gr SMKs.

I put this question to Dan Lilja when I built my 338-06 Imp. He suggested a 1:12 twist based on my desire to use the 210 Partition. It was a good call for the lighter bullets as I get consistent groups of 3/4" & under with the 210 Partition and 200 BT's. The groups open to 1-1/4 or so with heavier bullets like the 250 Partitions. I do not get the same level of accuracy with the longer 200 E-Tip & 210 TTSX's or 210 Scirocco's as I do with the shorter, more conventional designs but 3 shot groups in the 3/4" to 1-1/4" range are still the norm. Rifle is a Model 70 Classic with a 23" #3 Lilja barrel.

The 1-10 twist will stabilze the 300 SMK even in a 338-06. One would have to shoot much farther than 1,000 yards before needing more twist

I built a 338/06AI on a L61R SAKO action. I used the Shilen barrel with 1in10 inch twist. I shoot only 210 Nosler Part. bullets in it. I shoot clay pidgons setting on boulders at 300 yards hardley a miss. When I miss its my fault not the guns. Never shoot any heavier bullets than that. Maybe need faster twist for heavier and longer bullets, learned that with my 2, 6.5 x 55's trying to shoot light bullets. It has a 1 n 8 twist and loves 156 round nose bullets! They look like they are 1 & 3/16th" of an inch long!

While I agree that this should be the case, I have seen where it is not. for example a friend of mine has a 338WM that is very accurate with the 225gr Accubond. he wanted to shoot the 300gr SMK that I shoot out of my 338LapuaAI. this gun went from shooting 1/2" group's with the AB to 1/2 foot group's with the 300gr SMK, and yes it was checked at being a 1-10" twist

How do you accurately check the twist in-order to differenciate between a true 1-10 tist and a 1-10.4 twist for instance.

Were the holes in the target round of oblong? SOmetimes a load just isn't correct for a particular rifle

Just curious.

I tried some 325 grain Wildcat bullets in my 338 Lapua and I know that others were shooting them from a 1-10 twist with good resuslts. The bullets were key holing from my rifle and even broke the middle shade arm on my Olher 35, yet every twist calculator calculated them to stabilize in a 1-11 twist but for some reason I could not get them to in my rifle, so yes it can happen