Why the heavy points?

[john fletch]

I see quite often on the arrow components forum a request for heavy points.  Some even up to 250 grains?

Why?  What do you think is the advantage?

The times I tried anything heavier than 160 gr they dropped like rocks!  I prefer 125 gr and even 100 gr with light shafts.

Energy = mass times velocity squared

It is better to keep the speed up and the points sharp - you will have more energy on impact and with sharp points, good penetration. And the arrow will fly a flatter trajectory.

No intention of startng a ruckus here, but I would like to know what you think.  I would also like the science more than the opinion here as well.

[wtpops]

Simple version: Volkswagon and a desiel truck doing 60, both hit a brick wall. Which one is going to make it through the wall?

Trajectory with the way we shoot is a non issue. If you pratice with a heavy arrow your brain learns the trajectory and becomes a non-issue, now if you pratice with a light arrow then switch the weekend of the season then you have a problem

I try to stay around 10 to 11 gpp its just the trajectory my brains is used to.

Some use a lighter arrow and a heaver point to get the FOC up.

A lot of info on this in the Ashby reports.

[Zradix]

do some searching on FOC.

Realize the energy formula you're using gives you a figure that really doesn't pertain to the way an arrow uses energy to penetrate.

Just use a simple inertia formula...wt x speed.

wtpops has a good point...but...some bows might be able to get that "VW" arrow going 60mph but can't get the "big diesel" going 60mph. so the question ends up being more like a VW going 60 and a truck going 40...hard to figure in your head right.

SO...you need to figure is it better to have a lt arrow going faster or heavy going slower....just as you questioned in your post.

Don't double the speed in the energy equation it just gives a number that doesn't pertain to what we care about.

if possible...Take a heavy arrow that shoots straight out of your bow. I mean a heavy total arrow. at least 13grns/# hopefully more.

Then find a lighter arrow that shoots straight 10grn/# or less.

Shoot them into something side by side. Something that'll not have voids or give much..like a new block target or something. If you really want to see a difference suspend the target so it swings.

You'll hear a diff when the arrow hits.

You WILL see a movement diff and/or a penetration difference.

Here is a REAL example from my bow and my chrono.

   
Guess which arrow I use?
Hint..568 grn.

Also. if you do any reloading think about sectional density being important...not so much ft/#'s. our arrows aren't blowing up inside the animal to use up energy...just passin thru.


Fun stuff!

[wtpops]

Zardix, explained it a lot better, here are my numbers using his formula. this is a brand new set up im trying out. ft/sec is acording to Stu's calculator i have not ran this set up through a crono but with experence with other setup it looks to be very close.

Arrow #    628
ft/sec     180
wtXspeed   111,600
#draw      56
gpp        11.2
FOC        18.2%
ft/pounds  45.1

None of this means a hole lot except to those who likes to tinker of which i am one but i can tell you this setup hits a lot harder than any of my other setups. Benman Classic MFX with 250 up front

[KentuckyTJ]

John, I used to wonder why most trad folks shot heavy points. I shoot very light poundage 50 lb bows and like you didn't like seeing my arrow nose dive out at extended yards. FOR ME this was mainly on the 3-D course though. Our hunting shots here in the east are mainly inside 15 yards from trees and the drop really isn't an issue at those yardages. So I made the move to the masses. I will tell you that the penetration factor for the heavier setup over the lighter is the way to go on our deer.  Now your shots out West can be much longer and you will have to make your mind up to go heavier but I would suggest you give it a go.

[Bobaru]

John:  

Your analysis is spot on.

Many trad archers have the idea that super heavy arrows are superior.  Personally, I've not been able to demonstrate that, even though I've spent some amount of time trying.

So, keep on shooting the arrows that work best for you, and don't get too worked up about all the cross-talk on heavy arrows or high FOC because none of that stuff is substantiated by evidence that is reproducable.

[wtpops]

Here is somthing i found on a sponsor web site.

 The formula for momentum calculation is:
        “Momentum = mass multiplied by velocity or p = (m)x(v)”

(Note: You ask why P stands for momentum? “The symbol P for momentum comes from the original term used to describe persistence of the object's motion” )

 

The term “Persistence” describes how we want our arrow and broadhead to perform. Momentum or Persistence is what drives the arrow and broadhead into the animal. Momentum being the combination of arrow weight and velocity is what propels the arrow through the hide, tissue and bone. This is why Momentum is more meaningful to the bowhunter than Kinetic Energy. Going back to the formula for momentum we see that velocity plays a part but is not more significant than mass. From this we can conclude that if the velocity is kept constant and the weight of the arrow is increased the momentum (P) of the arrow is increased proportionally. This is good news particularly for the traditional archer. The traditional archer can concentrate on arrow mass which is easily controlled or varied rather than on velocity which generally can only be increased by shooting heavier draw weight bows. By increasing arrow weight or mass we can see a significant increase in Momentum (Persistence) and increased penetration potential. This opens up a new world in arrow design. We can study and experiment with “forward of center arrows” (FOC),”extreme forward of center arrows” (EFOC) and “ultra extreme forward of center arrows”(Ultra-EFOC).Remember the ball analogy; the heavier baseball does more damage on impact. The heavier slower arrow has more momentum (P) than the lighter arrow, and thus does more damage on impact and has persistence to penetrate. Summing up, calculations of KE for a light fast arrow may indicate high kinetic energy (KE) but will have a relatively low momentum (P) compared to a heavier arrow traveling at a slower speed.

 

Momentum (P) and Kinetic Energy (KE) along with weight forward of center arrows (WFOC) are being considered by more and more archers as they become educated and convinced that arrow speed alone does not kill!


As said above shoot the arrows that work best for you!! But you asked the question so we will try to help you with the answer and you make the choise that works for you.

Also as you can see buy Zradix chart there is a point in arrow weight where to much is not good also.

[park]

I dont have any science but common sense  tells me that if you are concerned about arrow penetration shoot a heavier bow.If you cant shoot a heavier bow workout until you can.As far as arrow weight goes its just like my dad would say where theres a loss theres a gain and where theres a gain theres a loss.You can only crunch number so long before you have to shoot a heavier bow to make an arrow shoot harder.

[wtpops]

Originally posted by park:
I dont have any science but common sense  tells me that if you are concerned about arrow penetration shoot a heavier bow.If you cant shoot a heavier bow workout until you can.As far as arrow weight goes its just like my dad would say where theres a loss theres a gain and where theres a gain theres a loss.You can only crunch number so long before you have to shoot a heavier bow to make an arrow shoot harder.

Park is right on, always shoot the heavest bow you can with out overbowing your self and efecting form but once you reach that point you can play with your arrow and help too.

With all this said if you do not like to tinker ,some do and some dont, just shoot what works for you after all we dont hunt elephants here in North America.

[GO Rogers]

Penetration!...........♠

[park]

[USN_Sam1385]

I love getting into the science and math of all this, because it is fun. But basically there is only one formula you need to know:

Arrow flying straight and accurate, from a bow with at least 40 lbs. of pull, and a razor sharp BH on the front = dead deer.

[straitera]

Fought heavier arrows a good while in favor of liteweights for speed. Zero question heavier arrows w/sharp bh will outpenetrate especially through bone. Find something you can live with. 750gr arrows are sleight light for my setup. But they're flat shooters.

[Mint]

I shoot heavy points because I get better penetration with EFOC shafts. I shoot GT 55/75 with a 50gr brass insert and 200gr muzzy phanton up front. Total arrow weight about 540grs. I don't think this is a "heavy" arrow.

[wtpops]

Originally posted by GO Rogers:
Penetration!...........♠

Short and sweet. I like it  

[Buckeye Trad Hunter]

As far as the heavt arrow argument goes you will have to experiment and see what works best for you.  Faster isn't always better if it just bounces off when it gets there.  On the same token, as you go heavy there will be a point of deminishing return.  A 1500 grain arrow isn't going to do a bit of good if it doesn't move fast enought to penetrate.  Each set up will have it's own specific bell curve for oreformance with different arrow weights.  As a general rule of thumb around 10 grains of arrow weight per pound of draw weight is a good place to be.  As far as the heavy point instead of overall arrow weight goes, your arrow will fly and penetrate better with more weight up front because the forward mass "pulls" your arrow through the air rather than your arrow being "pushed" by an arrow that is perfectly balanced or even tail heavy.  Sometimes people just order heavier points because it's a simpler way for them to get an arrow rough tuned or in my case I cut my arrows too short and had to have a heavier point because I didn't want to throw out a brand new dozen.  

[swampthing]

Gives you better "chance" on bloody pass through when a lousy shot has been made. On deer, turkey, b. bear, and -250lb hogs, why loose the trajectory. 475-525g arrow humming right along. I've had miserable results with 700g efoc set ups, wouldn't penetrate a hog shield to save my life. They were bare shaft tuned to 30yds, just food for thought.

[JamesKerr]

I shoot a heavy point for the extra FOC it gives me. I believe that the Ashby data is very conclusive on this, However I only am able to hunt whitetail and hogs, so I do not make up 700 grain arrows for my 55 pound bow I find that an arrow around 600 to 650 grains with 15 to 20% Foc works best for me.

[Ragnarok Forge]

Read thru the Ashby reports, this one has been proven and resolved in full.  Higher mass with efoc = increased penetration.

[Zradix]

most of this stuff is just icing on the cake....after you learn how to shoot accurately, tune an arrow/bow combo and learn how to get a broadhead sharp.
You don't NEED 13grn/# and high foc to kill stuff.
But the above might help in a not so perfect situation...I like to hedge my bets.

I also like tinkering with stuff...many don't