30 Cal 240 SMK and 1:10 Twist

Jon A

Well-Known Member
Dec 28, 2001
Mukilteo, WA
Sorry guys, I know this has been discussed here before but damned if I can find it!

Anyway, I want to try the 240's in my 1:10 twist 300 RUM. Hopefully velocity will be somewhere north of 2900 but I won't know for sure until I try.

Will I have any problems stablizing them?

The program I used to figure it sayes a 9 twist at 2900 and 10 twist at 3000 fps is required. It lookes borderline so I'd do some more research, again, if it were me.
I have a 1 in 10 twist on the Tomahawk and it works fine.

Most people shooting the 240 Gr 30 Cal MK do it in a 1 in 10 twist.

Less pressure and it is very accurate.

Darryl Cassel
Thanks guys. I was thinking they might be a bit borderline, but then I kept thinking of all the times I've read, "A bullet will be most accurate when just barely stabilized."

I think I'll give them a try.

10 twist will work just fine for the 240 gr bullet.

I would however, stick with the 220 gr in the 300 win mag. with a shorter barrel.
If your barrel was 36" I would say go with a 240 and see how it does.


[ 05-28-2002: Message edited by: Darryl Cassel ]
Darryl, would a 10 twist be okay from a 300 Win Mag or would it only work if velocity were higher? I can get the 220MK going 2900 safely but best accuracy is coming at 2850 or so from my 26" barreled 300 Win Mag. I imagine I could get the 240 going 2750 but accuracy may not be best at max velocity. Rufous.

Here is something very interesting I saw on accurate reloading.

Accuracy with 240gr SMK from a 7.62x39mm 1-10" twist. Muzzle velocity between 1790-1900 fps and accuracy from .245" - .872" at 100 yds with 5-shot groups.

These results kind of lead me to believe just about any .308 bore cartridge with a 1-10 twist will work with the 240gr SMK.

Maybe the real issue is: at what velocity will a 240gr SMK become unstable if spun at 1-10. Maybe before going subsonic?? I don't know.

I believe the 300 Whisper uses a 1-8 twist to shoot the 240gr SMK accurately at subsonic velocities.


[ 06-08-2002: Message edited by: MontanaMarine ]
Interesting, the program I have says 8 twist all the way to 2500 fps. before even a 9 twist will work. Must not be too terribly unstable, maybe just asleep, but with one eye still open.
Jon A, could you please post your accuracy evaluations regarding the 240gr smk in your 300RUM based on the 1-10 twist. Mine has a 26" tube and would be very interested to hear how well it performed for you...

Thanks in advance...

I'm gonna check with my buddy who just bought that LRP-1 in 300 RUM with the 1-10 Walther on it. He said he was going to handload some 240 MK's. I want to see how they do too. I want to find a 1K or 1.5K place to shoot if they work out good.
I'll post it at S.P. and here when I get some results.
Celt, what part of Indiana do you live in? I live in extreme southwest Indiana. A friend of mine has a 300 RUM A.I. He shoots the 240 MK in a 1-10 twist 28" long Hart barrel. He has gotten hits on 18" steel plates out to 2268 lazered yards. He uses H50BMG and pushes the bullet to 3000 fps with very good E.S. and accurcy in the 1/4 MOA range. I am lucky, my freinds and I can shoot out to 2500 yards from my back yard into one of the many ditch banks here in southwest Indiana.

Shoot Safe, Shoot Straight.....RiverRat
Jeff, good to go, would love hearing the results you get. Am also waiting to hear about your sucessful start up, as I have 2 candidates for make overs with your name on them...

Gary, that 300RUM AI sounds like a scorcher, keep knocking them down...

'Squatch........charlie mike

Glad to see you made it over here! I talked to Geoff last week, sounds like your new .308 is almost done. Getting close to a keeper load on the RUM. My regards to Steve & Saint Rita.
I should be up and ready to go after the zoning gets squared away. Late August.
Although I do have some news. Email me we can talk.

I live in North western IN about 30 min south of Valparaiso. or about an hour south east of Gary. Out in the farm country.
I have a 450 yd range at the shop / clubhouse. But it is hard to get any of the farmers to let us shoot 1K on the ditch banks.

My email is
[email protected]
Feel free to get ahold of me. I would love to shoot some looong range stuff.

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