The Easton charts are notorious for being wrong with traditional bows. Being that your arrows are cut to 27.5",I'm guessing you're drawing 26"...maybe 26.5". The 2115 has a deflection of around .460" whereas a 1916 is about .620"...big differance. And that's with 28" shafts. Cut them shorter than that and the spine increases...alot. If the 1916's are cut to 27.5",that'll stiffen them up a bit to shoot good. You're most likely drawing about 50-52lbs so with a good release,you're getting good flight. A 2016 would be a good choice(better than the 2115).