ORIGINAL: BGfisher
Pretty good advice above. There is no doubt your arrows are underspined, grossly so. I shoot a 500 spine at 27" (bow is 27" draw) and about 63# is the upper limit even with 80 grain target points.
I'd agree that you should be shooting 400's, and possibly 340's. You're kinda right there where you could make either work. Another arrow you could check out is the Gold Tip Ultralite 22 series. Larger diameter and lighter so a little more speed, plus line cutting ability.
And yeh, personally I'd like a better quality arrow than the Epic if serious about shooting any target venue. If your shop only carries Epic then it must be a very small shop or he's hard headed and brand loyal. There are lots of other choices in the arrow industry.Don't limit your choices because of a shop's proximity. You can do a lot of searching right here on the computer. Frankly I would look elsewhere simply because he set you up with grossly underspined arrows---or you changed something since he sold you those.
Everything he said.
NO LOOP,there is no way you need to shoot the 400's. at your current poundage.
You are slightly weak with 400's and a loop so without it,you are way underspined.
Are you wanting to shoot a hunting class or what.