If your bow does not have laminated wood limbs. I would shoot for a total arrow weight (including broadhead) of 245gr to 250gr., at 40 lbs. Around 6.2 grains of arrow per pound of bow pull weight. If the bow is noisy, You can increase the arrow weight or use a variety of vibration dampening devices but, add as little as possible to the string. Every item added to the string reduces the speed.

If your bow has laminated wood limbs. I would shoot for a total arrow weight (including broadhead) of 335gr to 345gr at 40 lbs. Around 8.5 grains of arrow per pound of bow pull weight. Again, if bow is noisy. Increase arrow weight or add vibration dampening devices.

Good luck

I guess i put the wrong pull back on my first post well m bow is really around 50 pd pulld sry i guees i will have to do the math also how do you weigh an arrow once your done tuning and setting it up.

Go to Eastons site.
http://www.eastonarchery.com/
Go downloads.
Load arrow selector.

A safe call would be.
Bows with wood/wood laminate limbs. Arrow with broadhead should weigh at least 8.5 grains per pound of pull. At 50# 425gr
Modern compounds without wood laminate limbs. Arrow, including broadhead, should weigh 6.5 grains per pound. At 50# 325gr

You can go as low as 8.0 and 6.0 respectively!!!

You need a grain scale to weigh arrows. A bullet reloading scale will work. I use an RCBS 502 reloading scale to weigh everything.