Green Mountain twist rate?

I bilt a Galil AR using a Green Mountain barrel. The Galil was a kit that was several years old and never completed when I bought it. The rifle will not stabilize a 55 grain flm worth a dar, however it liked the M855 ball ammo.
What is the twist rate of the Green Mountain Galil barrel? I tried the cleaning rod/tape trick with mixed results.

The current barrels Century use for the Golanis have a 1 in 9 twist. Any 1 in 9 will stabilize the 55 grain or 62 grain bullets equally well. My 1 in 7 NM AR shot the 55 grain South African surplus into very small holes at 100 yards. I did have problems shooting 50 grain hollow point bulllets, they started coming apart on me, probably due to being rotated too fast.

The resason I posted was that the 55 grain bullets were like a shot gun at 100 yards. the M855 Ball was shooting 3 shot clover-leaves groups.

Could very possibly be a 1 in 7 twist. Why not just measure it?

-myers