I am looking for some new arrows. I have used the Carbon Fury 4560 from Bass Pro. My opinion..... Eh. So / so. I broke allot of them (well, almost all of them)

Anyway, I am shooting 55lbs and my arrow length is 27.5. I am a little confused about selecting an arrow that is right on the border. Any ideas??

Don't make the same mistake I made and get the wrong arrows. You are right on the edge, so go with the 5575 (stiffer spine) for sure. It will also be a more consistant arrow spine for you and increase your accuracy some. I'm on the edge of a .340 spine and a .300 spine. I look forward to getting my .300 spine arrows. Always favor the stiffer spine, I learned this the hard way.

I agree with Mildot,if you are borderline,always go with the stiffer spine.

Isn't the spine stiffness based on the arrows "original" length of 30" or 32"?

I think you'd have to figure in arrow length too. If he has a short draw length he could cut the 4555's down to the "correct" length and stiffen the spine that way.

However, if he has a longer draw length 29 or above, I'd say the 5575's would be better.

my 2 cents

I just learned a few days ago that thearrow spine is based off of 28 inches of arrow length, not 30-32 material length. He stated 27.5 inch arrows, so I trusted that he already had them cut at the length he was happy with. I think that we can all agree that the 5575's are the better choice.