Twist and subsonic .22's

[shooter58]

I shoot air rifles and am looking for a .22 barrel that will stabilize a 44 gr .22 soft lead boolit at 1000 fps or a bit less. The online twist calculators that let you input a speed variable either tell me I'm shooting too slow, or recommend a 1 in 10" twist. My present barrel is a 1 in 17 1/2" twist and will group boolits in an inch at a bit beyond 40 yards. The targets show some yaw at 40 yards, and at 60 yards the boolits still don't keyhole but groups open to two inches.
I am thinking of getting a Green Mountain barrel for a .22 mag with a 1 in 14" twist. I don't want to lose the ability to shoot regular waisted pellets if I can help it, so I'd like to stay away from a larger bore center fire barrel. The basic Greenhill formula makes it look like a 14" twist should work for me, but before I spring for a barrel, I want to dip into the knowledge base here.... experience trumps theory in my book.
If I need a dedicated "boolit barrel" in a 10" or 12" twist, so be it, but I'm hoping the .22 mag barrel will work in both worlds... pellets & boolits. Any advice ya'll can offer is welcome. Thanks... Mike

[runfiverun]

you will be duplicating 22 lr velocities with a slightly heavier boolit.
i'd look at thier twist rate and possibly go one turn faster for the heavier projectile.
i doubt that a little overstabilization at the velocities you are using is even going to show up.
the 17 twist does show unstability issues and a 14 twist would certainly improve on that.
however if you decide at some point to use a lighter boolit or go for less velocity will it be enough?
if you are going for the one projectile at one velocity the 14 should be fine.

[Doc Highwall]

If you look at the Wolf and Eley target ammo they are shooting at 1035 fps with a 1-16" twist and either CCI or Federal made a 22lr silhouette round with a 45 grain bullet.

[HORNET]

Winchester Super-Silhouette's were 42 grains. They weren't known for extreme accuracy in 16"twist rimfire barrels but sure worked good on tree rats. I finally ran out last year (shucky-darn).

[Artful]

Well for what little I know.

http://www.guns.connect.fi/gow/aquila.jpg
For Aguila's 60 grain SSS Sniper Sub Sonic's it's recommended at least a 1:12 twist rate in rifles shooting it at mid 800's with some selling as fast as 1:9 replacement barrels for 10/22 Rugers on shorter barrels going as slow as low 700's fps wise ... your bullet is lighter at 44 grains, but it's the length of bullet not the weight that matters.

Standard 22LR 40 grain work fine with subsonic speeds with barrels 1:14 to 1:16 -
If it was me I'd go for 12" to hedge my bets... Have you asked green mountain what they think? and is the barrel .2205" for 22LR or .224" for 22 WMR?

Have you got a length for this 44 grain boolit?

[shooter58]

They mic at .499" / .500" length, .219 dia, and are hollow points. I borrowed an older AR6 from a friend and found that it had a 1 in 14" twist barrel as factory original. The weather isn't working for me here, rain and wind today, but an initial check still showed a bit of yaw at 40 yards. It looks like it's gonna take a centerfire barrel to get the twist required to stabilize these. That's ok, it's a learning experience, if it comes to naught.

[Artful]

Miller Stability factor calculations
1:10 @ 900 = 2.911 green stable
1:12 @ 900 = 1.917 green stable
1:14 @ 900 = 1.485 green stable
1:16 @ 900 = 1.137 barely stable

1:16 @ 800 = 1.037 yellow marginally stable
1:14 @ 800 = 1.354 Barely stable
1:12 @ 800 = 1.843 green stable
1:10 @ 800 = 2.654 green stable

Miller suggests 1.2 and above as stable but my experience is 1.5 and above to be sure.

greenhill formula suggests 10.3 twist as optimum
http://kwk.us/twist.html

but again real life beats the calculations... if the 1:14 didn't stablalize go quicker