The bow is a 55@28 super mag 48. I want to use a 225 grain broadhead what size and length legacy shaft would I need?

2020 shaft,  what is your draw length? If its 28" I would go 29.5" on the shaft. But this is just for starters. You really need to play around with some shafts to find the best one for you and the bow.

My draw is just a touch over 28 I cant really try to many shafts as I just had my son and I am in college so money is very tight

2117's cut 29"....

If yo want to try 2117 as joe suggests (he gives good advice) I might have a couple you could have.

You could also try a 2018. (nut)

My suggestion would be 2216 at 30"
John

2018, 2020, 2117 all good choices because of higher overall weight

2018 would be no good at 29 or 30"s with that much weight up front. The 2117 and the 2020 would both most likely work for ya I would go with the 2117, start with it at 30"s and cut back a 1/2" at a time until ya get the flight ya want. My guess is 29.5"s will be about perfect with 225 up front. Shawn

I am goin with a 30" 2512...  A 2219 and 2315 will also be close..