No Chrony

[Fishhook]

I am not near a chronograph and I would appreciate you experts on speed, give me an idea how fast.
Switchback, 28" draw, 70 lbs pull, nothing on string but a loop.
Trophy Taker Shaky Hunter rest
GT Expedition Hunter 5575 arrows 27 1/4" from end of insert to split in nock.
4" straight vanes
100 grain field tip
Any more info I need to give?
Thank you all for helping a dummy

[TerryM]

I would guess @ 280 fps, starting with the advertised IBO numbers.

[jerseyhunter]

Simple with the following generalizations. Start with the IBO speed for your bow.

Subtract 10 fps for every inch of draw length you are below the 30 inch "test standard".

Next subtract approximately 1 fps for every 3-4 grains of arrow weight you are above the IBO "test standard" arrow weight of 350 grains. (a 460 grain arrow would cost you about 27-34 fps)

Next add or subtract approximately 1.75 fps for every pound of draw weigth you are eitherover or under, respectively, the IBO "test standard" weight of 70 pounds.

Lastly, subtract approximately 4-5 fps for every string accessory you have installed on the bow...peep sight, string silencers, string loop, etc...

Then take all of those numbers and subtract/add them to your IBO speed rating to determine a fair estimate as to your speed.

[MOTOWNHONKEY]

I have a Switchback and shoot a 400 grain arrow with magnus 100 stingers. 275fps. Them deer might as well lay over dead already.

[zac76156]

Hey MOTOWN,what draw length is that Switchback?

[hunt4hogs]

I have a switchback and I shoot 280 fps.28 inch draw,65 lbs,330grain arrow

[PABowhntr]

Simple with the following generalizations. Start with the IBO speed for your bow.

Subtract 10 fps for every inch of draw length you are below the 30 inch "test standard".

Next subtract approximately 1 fps for every 3-4 grains of arrow weight you are above the IBO "test standard" arrow weight of 350 grains. (a 460 grain arrow would cost you about 27-34 fps)

Next add or subtract approximately 1.75 fps for every pound of draw weigth you are eitherover or under, respectively, the IBO "test standard" weight of 70 pounds.

Lastly, subtract approximately 4-5 fps for every string accessory you have installed on the bow...peep sight, string silencers, string loop, etc...

Then take all of those numbers and subtract/add them to your IBO speed rating to determine a fair estimate as to your speed.

All of that sounds vaguely familiar.

[jerseyhunter]

All of that sounds vaguely familiar.

Thank you for the formula.

I copy all good info down for future use. But the credit belongs to you.

[Lung Buster]

Fishook I shoot a 395 grain arrow and got Chronoed last week it shot out of my 28.5 inch draw Switchback at 70 lbs 279 fps hope that helps.

[TeeJay]

I shoot a outback set up the same 264 fps