the kidd

well i bought some beman ics hunter 400 @ 30 in i have an aproxiametly 27.5 inch drawwitha loop string....i was wonderin cus i have a muzzy zero effect rest and it doesnt sit on the shelf like other rests do it sits behind it..i was readin the easton tuning guide and its says to cut the arrow1 inch in front of the rest,but i will feel scared with a broadhead set above the shelf[it looks like the broadhead could cut my hand]...but idk can someone plz help

Paul L Mohr

The correct AMO arrow length is 1 inch in front of where the arrow contacts the rest. And this is where most charts and online calculators are going to calculate spine from. This is also the point you would measure brace height and power stroke from. You will notice they either ask for draw length, or arrow length not both. So they (arrow charts) just assume you are using the correct arrow length for your draw length. If you are not you need to know how to fudge the numbers some. It will still get you fairly close though. And remember the arrow charts and online calculators are just estimated guesses to get close. They don't ask any where near enough information to be accurate.

The problem is this was based on people using conventional prong type rests set up correctly. Which would put the contact point of the arrow and the prongs right above your grip. Many of the newer rest actually set up behind shelf and work as a slight overdraw and the contact point could be 2 inches or more behind where it really should be. If you followed the rule of one inch beyond the contact point of the rest you would end up with shorter arrows than you really need.

AMO draw length is figured by measuring your power stroke or "true draw" and then adding 1.75 inches to that number. Basically just nock a full length arrow ( or one that you know is longer than your draw length), then draw the bow back and have someone mark the arrow right above your grip. Then measure the length from the nock grove to the end of the shaft (not the tip if one is installed!). This is your true draw or power stroke. Add an inch and 3 quarters to that length (1.75") and that is your AMO draw length.

So basically you can just cut your arrows 3/4 of inch shorter than your draw length as long as you know your draw length is correct. A lot of people just cut their arrows the same length as their draw length to cut down on confusion. In most cases 3/4 of an inch isn't going to make a huge deal. Unless you were close on being under spined or something.

A shorter than needed arrow will be stiffer in spine and weigh slightly less, a longer than normal arrow will be weaker in spine and weigh more.

Your actual arrow length really doesn't matter as long you match the spine correctly. Someone that is really familiar with certain arrows and the spine charts might be able to this, or there is software available that figures it for you. I use Ontraget2, it lets me enter any length arrow I want and it will tell me what sizes will work at that length. I shoot a longer than needed arrow.

There are advantages and disadvantages to shooting shorter or longer arrows than needed. It would depend on your needs and what you wanted to do.

Paul

the kidd

thanks alot paul reallly informative..i was wanting to mainly use this setup for hunting and just target shooting like practicing before i go on the hunt... i have a set of 500 26 in arrows but i was thinkin those might be to weak right and i might have to drop my poundage a little.. i also have some long ones like 30 inches @ 400 spine..i was thinkin of just cutting them a couple of inches...cutting them will make the spine stiffer rite and the longer the arrow the weker it is ?am i correct?

nodog

I'm with you, no bh behind my fingers. I can just see my finger sticking up some time, bearing down on something. Would love too lope some more off the shaft, just can't bring myself to doing it.

Good post Paul. I'd just add that a shorter shaft may get a person into a 400 spine from a 340. In some shafts that's a considerable reduction in weight/more speed.

Trying out the heavier FMJ's, a 400 would be nice, but I just can't make them shorter. Stuck with the 340's at over 11 grns/in.

Roskoe

Arrow length is just one of the "tools" - along with draw weight and tip weight - to fine tune the arrow spine to your bow. I use the charts to get in the ball park, and then start with full length shafts - comparing fletched shafts to bare shafts at 20 yards, cutting an inch at a time off of each -until the bare shafts are hitting the target straight and at the same spot as the fletched ones. Too long/soft of a shaft is going to print the bare shaft angling to the right of a fletched shaft. Once I get the two shafts hitting the target straight and at the same place, it doesn't really matter to me if the broadheads, at full draw, are 1/2" ahead of the arrow rest or 2 1/2" forward.

Having already done some bare shaft tuning with a Fred Bear Instinct, I would suspect a 400 series Easton arrow at about 30" with a 100 grain head would be very close - assuming the 58 lb draw was accurate. I don't think you could get the 500 series shafts short enough to spine out, without reducing point weight and/or decreasing the draw weight, at your draw length.

wicked arrow

my last bow the rest sat above the riser so my bh came
right to my rest.but noe my new bowtech my shaffers rest sit behind my riser so i had them cut when i pull the bow back the broadhead will be right at the outside of the riser right above my fingers,i have onescare on my thumb from a wild draw dont want a another scare,,,but i could easily cut two more inches off my arrows if i wanted,that would put me at 26"