RobVT3

I'm trying to increase my FOC without weakening my spine too much. I shoot 29" Gold Tip Hunter XT 7595's with 3 4" feathers and a 100 grain point. When I move up to a 125 grain point, according to OnTarget2, it weakens the spine too much. Has anyone ever tried the screw in weightsforinserts? Is this an acceptable method for increasing FOC? My current FOC is 10.38%. Is this acceptable for shooting broadheads?

Thanks,
-Rob

brucelanthier

Whether you use a heavier tip or screw in weights you will still be increasing the tip weight and weakening spine. Some will say that an FOC of 10.38% is OK but most would recommend a FOC between 12-15%. You could try cutting a .5" or 1" from the fletching end of the arrow to make it 28" or 28.5". That may bring the spine back into balance with the increased tip weight.

MDBUCKHUNTER

10.38% is fine for hunting with bh's. I wouldn't go any lower than 10% though.

You are too week spined with 7595's at 125 gr????

How fast are you shooting?

Also, did you setup OT2 with an actual chrono measurement or are you just basing it on what the program hypothetically gives you?

The Rev

Ausie-guy is working at putting together 20% foc using 220 grain broad heads. He has an awesome program to put it all together. His arrows are packing one heck of a punch. I can't wait to shoot them.

brucelanthier

The arrows I am using have a 225 grain tip, one has a 242 grain tip and are at 17% FOC. The 242 grain tip uses the Muzzy Phantom w/bleeders (220 grains + 22 grain insert). The other arrows have 100 grain inserts and 125 grain broadheads (slick tricks and crimson talons).

bow_hunter44

I second that. 7595's that are weak spined with 125 grain broadheads??!! One would think that arrows that stiff could use a Volkswagon for a tip!! My hunting arrow is an Arrow Dynamics 'Big Game' (designed for, among other things, a high FOC) that is heavily spined. My broadhead is a 220 grain Muzzy Phantom SS. I do use a wrap so I keep everything else on the back end as light as possible. The result is a FOC of 19%. I'm having a hard time keeping them in my target - cool!!

BobCo19-65

My arrows came out to 21% FOC. Not 100% sure I like the arrow though.

From a prior post:

RobVT3

When I have the draw weight set at 70lbs it shows the spine on the weak side of good. Based on what I've read on the forum most agree that an overspined arrow is better. I'm basing mychrono on the hypothetical. I figured that witha screw in weight I might be able to get a higher FOC without as much loss in spine as I would have from a25 grain increase on the tip. Maybe it would be insignificant though. Either way I would like to fix the problem without having to invest in a new size broadhead if possible. I havea bunch of100 gr. Slick Tricks, Muzzys and Razorbacks that haven't had the opportunity of passing through a deer.

Edited to add....

I'm also considering lowering the draw weight. It's probably at little high at70lbs anyway.

Arthur P

I'm in pretty much the same boat at 32" and 65 lbs. The chart shows 100 grain points being right on the cusp of being underspined with 7595's. [&o]

Any weight added to the front of the arrow will have the same effect on spine, whether the weight is in the tip or in the insert. So screw-in weights won't help you.

The other option to increase FOC % is to take weight off the tail end of the arrow, if possible, by using smaller fletching or feathers.

MDBUCKHUNTER

That is where you are going wrong. Have your bow Chrono'd with your current setup. Then with the OT2 software, input all your equipment information. Then raise/lower your IBO # until you get the speed that the chrono told you. Then check your spine and see what your arrow is then.

The hypothetical is exactly that...a guess at what you are shooting. Get the real results and then input them into the OT2 software package.

Good Luck!