Hi i got the following bow
2004 bow tech liberty
28 draw
wisker bisket
70 pounds
tube peep
string loop
string leeches

I shot 550 grain arrows and just got 220 feet per second i just bought 390 total with field point. What should i get now for fps?

anyone

I think your arrow weight is incorrect for the first, heavy arrow. A 2004 Liberty is rated around 308 fps IBO, and according to my calc's you would shoot a 550 grain arrow at:

308 IBO
- 66.6 (for 200 grains over IBO)
-15 (for tube + string leeches)
-20 (for 2" under IBO)
= 206 fps

For a 390 grain arrow you'd get approximately:

308 IBO
- 13.3 (for 40 grains over IBO)
- 15 (for tube + string leeches)
-20 (for 2" under IBO)
= 259.7 fps.

what arrows do the liberty or whats the recommended weight or arrow for my bow tech? What does 308 mean, a grain arrow?

The 308 means feet per second.

what weight did they use to get 308

30" draw......350 grain arrow.......oh yeah....nothing on the string!

At 28" and 390 grains and a nock set, and small peep sight with no tubing, you'll probably get 265 to 270

GoodLuck!