Consistent Gravity Readings, not enough attentuation

[masteroflobsters]

I brewed a kolsch, and the original gravity was 1.056 (maybe slightly higher). Last Thursday, I took a gravity reading, and it was down to 1.017. Three days later, the gravity was the same. The problem is that, according to an abv calculator, the "apparent attenuation" was only 69%, while the yeast I used has an attenuation of 73-77%. Is this a problem? I brewed one gallon of beer, and the instructions from the store said that it should be done fermenting in 5-10 days, and it has been 8 days. I know that that is not very long, but my hydrometer readings have been consistent at 1.017.

Should I bottle now, or should I wait?

 

[TheBrewingBear]

I would wait it out. Time solves many beer issues. How do the samples taste?

Other ideas: temperature correction on readings or slight wort carmelization.

 

[Yooper]

The "average attenuation" is just that- an average. You are below the average, but of course many people are (the definition of "average").

Don't worry about it. Bottle it when it's clear and it will be fine!

 

[fatnoah]

Have you calibrated your hydrometer? Mine is off by 0.004. That could be where your "missing" gravity points are.