Re: 1:8 or 1:9...
The perils of buttoned barrels. I normally expect to see as much as +/- one inch from the stated twist in buttoned barrels. Unfortunately, it's sort of a crap shoot as to whether the variation will be on the "fast" or "slow" end of the listed twist.
Always opt for the faster of two twists if you think it's anywhere close to being marginal. Too fast a twist (even when it's a bunch too fast) will almost never cause a prblem; too slow a twist will ALWAYS case a problem.