feet per second on my bow

[j.trevor123]

Hello I have a mathews Fx and am curious as to what my feet per second is. I shoot a 59 lb bow with a 29' draw length. My arrow weight is about 372 grains. Is there a fairly accurate way to calculate FBS or does it change from bow to bow in a way its hard to determine.

[mg66]

Any calculators out on the net give a so-so figure. I took mine to my local pro shop and shot 3 arrows through a chronograph and then took an average of the three. A lot of variables come into the picture:

Do you use string silencing spiders?
What kind of peep sight?
New or old stings (is there any string stretch)?

All the above and other factors take fps off the arrow speed.

At a guess yours may be around the 240 to 250 mark as you are only shooting a 59lb draw weight but only a chrono will tell the actual figure.

The results for my Mathews Ultra2 is:

Arrow and Speed Specs using Gold Tip 5575 XT Hunter Carbon Shafts

Total Arrow Weight = 375 grains
Draw Weight = 70 lbs
Draw Length = 30"

Chronograph Speed = 283 fps
Kinetic Energy = 66.71 ft/lbs

My bow has an advertised rating of 320+ fps ... in the real world it aint all that but still is right up there. I use to shoot 490 grain aluminum @ 65lb and it shot 247 fps. By switching to carbon shafts I reduced total arrow weight by 115 grains and increasing draw weight by 5# to 70# gave me an extra 36 fps. And the main point is that its still very quiet. The difference of AMO versus IBO at http://www.bghi.us/index.php?x=bowspeed

[j.trevor123]

ohh thanks for the reply, yah i actually got it chronoed today, looked about 221 fps. haha which i think is okay for 59 lbs. Not that its that big of a deal but can anyone tell me how these companies say the speed it shoots and i dont hear anyone getting these speeds with the conditions givin for the IBO or AMO. I mean it says on mathews website that with a 540 grain arrow, 60 lb, 30 inch dra (AMO) that this bow reaches 235 fps. and i have about a 28.5-29inch dray and a 375, give or take a few grain arrow and shooting 59 lbs and only getting 220! i Mean i would think with my arrow being so much lighter than the tested it would atleast make up for it and be around 235. But i guess i shouldnt complain to much it shoots great and hasnt failed me yet on any animals.

Also i would like more weight but isnt it bad on kinetic energy and the bow to lower the arrow more than about 6 grains per lb draw weight?