PDA

View Full Version : 100 vs 125 gr heads?



boobowbender
06-02-2011, 12:39 PM
been shooting 100's for years now, but with my f/c shooting so fast should i consider going up to 125's for extra foc and knock down power? I will only be shooting whitetails and no further than 30 yards, but i like to practice at 50 and 60 yds

p.s. fellas, finally got this thing tweeked and tuned shoots amazing finally! No more trg and timed to perfection.

Hutch~n~Son Archery
06-02-2011, 03:05 PM
About time you are having fun! How stiff are your arrows? would show if you really need to go 125 gr. A little more punch might not be so bad but how much change will it make?


Hutch:cool:

gravedigger
06-02-2011, 03:56 PM
i started a thread allmost the same.might be some good info for ya.
http://martinarchery.com/mtechforum/showthread.php?9560-100-125gr-how-does-this-affect-arrow-flight&highlight=broadheads

Destroyer
06-02-2011, 04:06 PM
No difference at all except for affecting the spine. The extra 25 grains won't give you anymore 'knock down power' because bows have none. Some believe more FOC makes some difference to accuracy but I haven't seen any proof of it.

Going to 125g might give you more of a choice in broadheads though.

wick
06-02-2011, 05:20 PM
Yes you may have to change arrow spine. but I am a big believer in FOC too. especially when it comes to broadhead tuning. Maybe its all in my head but I feel that more weight forward helps the my arrow track better. I've never had any evidence of more nock down power or an arrow that hits harder even though it seems like it would make sense with more weight travling down range. I shoot 125gr just for the FOC. And my dad telling me they hit harder.:)

wscywabbit
06-02-2011, 05:29 PM
It just depends, I think there is a trade off in there somewhere. I prefer about 13% FOC myself. My friend shoots (and kills) at about 9%.

I grew up in eastern Oregon, in the land of the wheat field and dirt clod fights were a fact of life. Grab a handfull of straw and toss it; If you have a decent dirt clod attached it will fly pretty good, if not it kinda goes where ever. Too much clod though and it won't be as fun because it won't go as far. :p

wick
06-02-2011, 05:36 PM
It just depends, I think there is a trade off in there somewhere. I prefer about 13% FOC myself. My friend shoots (and kills) at about 9%.

I grew up in eastern Oregon, in the land of the wheat field and dirt clod fights were a fact of life. Grab a handfull of straw and toss it; If you have a decent dirt clod attached it will fly pretty good, if not it kinda goes where ever. Too much clod though and it won't be as fun because it won't go as far. :p

I bet a heavier dirt clod hurts more than a light one.

boobowbender
06-02-2011, 07:30 PM
nice analogy fellas,
anyways gravedigger i remember that thread and tried looking up dr ashbys research musta looked up wrong page because it was all garbage but found the goodstuff today thanks

got another question, but i'll start a new thread

Conan
06-02-2011, 07:37 PM
I bet a heavier dirt clod hurts more than a light one.

But dirt clods don't have a super sharp razor attached to the front. It doesn't need to knock down a deer, just cause enough tissue damage to make them drown in their own blood.

boobowbender
06-02-2011, 08:07 PM
well said conan
a little dark, but i think we all like killing things on this forum!
Welcome

Rockyhud
06-03-2011, 03:27 PM
If you've read the Ashby reports you'll quickly discover the advantage of heavier and higher FOC arrows. The added mass provides more momentum which enables the arrow to keep moving forward even after it's encountered the game animal. This can be especially helpful if/when bone is in the path as the increased weight helps the arrow and broadhead to go deeper to get to the vitals and increases the potential for a lethal hit.

As far as accuracy goes, I've experienced an improvement in tighter groups with higher weight and FOC arrows. They also aren't affected by winds, especially cross winds, as much as lighter weight/FOC arrows.

Destroyer
06-03-2011, 03:58 PM
The added mass provides more momentum

Yep but we are only talking 25 grains here, there wont be much of a difference.


They also aren't affected by winds, especially cross winds, as much as lighter weight/FOC arrows.

You need to separate the two, one is proven the other is theory. Same arrow weight with different foc won't make a difference to wind resistance.

Rockyhud
06-04-2011, 08:04 AM
I beg to differ on both accounts, Destroyer. Higher FOC arrows will fly better and group better. Take a look at Olympic archers and what they shoot - high FOC. And these folks shoot at longer ranges than most hunters ever will. Higher FOC will also not be affected by winds as much due to the majority of arrow weight being up front which follows the same physics principle that a mass that is moving tends to stay moving. The heavier front end doesn't get blown about as easily as a light weight front end. I know this as I used to shoot arrows with about 8% FOC. In light to no wind conditions they flew and grouped decently but in higher wind conditions I could not get the same results. When I started using heavier weight/high FOC arrows I discovered the advantages of both have in windier conditions, especially at longer ranges (30-60 yards). They also tend to group at least as well, if not slightly better, in light to no wind conditions.

If anyone wants to gain more knowledge on these topics than I can provide there is a great wealth of field test data that Dr Ed Ashby has compiled and published from his almost 30 years of in-field testing. All his reports can be found here (http://www.tradgang.com/ashby/).

I will admit though, the primary reason I switched to heavier/high FOC arrows was for the advantages they provide in hunting situations. Ashby's theory, and mine, is the hunter should prepare for the worst case scenario and hope for the best. This means we, as ethical hunters, should use the best archery ammo we can for a quick, humane kill on whatever game animal we're hunt. And it doesn't matter who the hunter is or how good he is (or claims to be), no-one can control the situation when hunting wild game. You never know if the animal will change position when the arrow arrives or if a strong gust of wind kicks up when you don't expect it or perhaps a small twig the hunter didn't see slightly interferes with the arrow flight. Any of these things can change the intended point of impact on the animal. When these things happen a heavier/high FOC arrow has the potential to increase the lethality of the arrow by not being as easily deflected by obstacles such as wind, heavy bone and such.

Destroyer
06-04-2011, 06:17 PM
Higher FOC arrows will fly better and group better.

If it was proven we would all be using light stiff shafts with 160+ grain heads. We don't.


Take a look at Olympic archers and what they shoot - high FOC.

Most of the high FOC for olympic archers comes from using a light/slow recurve at long distances with tiny fletching and a finger release. The tiny fletching promotes high foc in the first place. The idea is to try to adjust your arrow to get the best groups/accuracy by going up or down with foc. Because of the speed, low arrow weight and distance, minute changes can have an effect. Doesn't mean that going higher foc always improves accuracy.


Higher FOC will also not be affected by winds as much due to the majority of arrow weight being up front which follows the same physics principle that a mass that is moving tends to stay moving.

This makes things worse. By having all the weight up front, the rest of the shaft gets blown around more. Then the fletching corrects but this pushes the arrow off course. With a heavier weight evenly distributed its less likely to do this.


a heavier/high FOC arrow has the potential to increase the lethality of the arrow by not being as easily deflected by obstacles such as wind, heavy bone and such.

Again, not true. Even the slightest hit of a leaf/branch/whatever can result in a big deflection, especially if the deflection is close and the target is a distance away. If the head hits first its bad news for accuracy regardless of the foc. If you have a high FOC with a lighter weight at the nock end and that is where it hits, more deflection, the lighter end gets deflected more.

FOC makes no difference in penetrating bone at all, that all comes down to mass, momentum, size/strength of the head.

wick
06-04-2011, 06:54 PM
personally i think its about finding that perfect balance that you both shoot well with and comfortable with. Too high of FOC can have negative effects while i think not enough can have negative impacts as it relates to broadhead travel too, like how the air currents catch the blades of the broadhead and impact it's flight. they are more likely to streer the arrow off coarse than the shaft or trail end of the arrow I've driven myself nuts trying to find that perfectly balanced arrow that is right for my bow but also am confident with shooting in differnt situations while providing optimum speed. I am just under 13% FOC with my current set-up and am very happy with it. 125 gr. good bone busting results and the wind don't bother me.

Rockyhud
06-06-2011, 09:35 AM
Well, all I'll say for this thread is this. If you haven't, or aren't willing to read and understand the extensive field test reports by Dr Ashby and/or haven't actually spent the time and effort to experiment significantly with different arrow weights and FOC then it's just each to his own thoughts. I personally have read Ashby's reports and experimented and found his real life, in field tests to be well founded and accurate. That's why I now use heavier arrows with high FOC.

wick
06-06-2011, 07:00 PM
I actually clicked on the link for Dr. Ashby and yes it is extensive but I am Impressed that someone has taken the time to scientifically test all this out. I am going to sit down and read his findings when I have time. Good to have as much info as possible. Thanks.

Destroyer
06-06-2011, 08:55 PM
If you haven't, or aren't willing to read and understand the extensive field test reports by Dr Ashby and/or haven't actually spent the time and effort to experiment significantly with different arrow weights and FOC then it's just each to his own thoughts.

A bit passive aggressive mate. I have tried to digest the rather old (1996) generalized rubbish from the link you have provided but I cant find anything of any substance there. A few calculations, a few graphs and the normal scientific rubbish that seems to more about impressing everybody then about proving anything.

Example:


arrow momentum derived through increasing arrow mass results in a greater gain in penetration than does momentum gained by increasing an arrow’s velocity. This is true because the tissue’s resistance is increased by the square of the velocity.

Just blah, blah, blah really.