what size arrows would you recommend?

[pj starrett]

I am shooting a martin rebel 50#@28"..I am currently shooting 2313 aluminum..is this the right size or is it too big?

[Hot Hap]

Sounds a little stiff. What`s your draw length?

[Killdeer]

2013 or 2016 to start, tweak with length and head weight.

Killdeer  

[Goose]

I think Hot Hap and Killdeer are pretty much on the money.  IF you are drawing 28" with a 29" arrow, 2313 is way too stiff. Like Killdeer said, try the 2016, and she may also be correct about the 2013.  The 2016 is just a little tougher shaft.  
Good luck.
Goose

[wapiti792]

I second the 2013 or 16. I doot a 51# at 29 CM Hunter 2. 2016s with 125grain head fly great out of it.

[tpoof]

My Bushmaster throws 1916's with a 125gr pt perfect!
bareshaft perfect as well! 281/2' shaft 27"draw

[Gordy]

If your draw and arrow are longer try 2018 or even stiffer.

All depends on your draw on that bow, point weight and arrow length.  I shoot my 51# with 31" 2117's and 145's.  Sounds stiff, but that's just me...with a near 29.75 draw on that particular bow. I'm one of the few guys who the Easton chart works for.