I shoot a 523 Gr Easton Axis 300. 10.7 GPI. 25 Gr insert. 10 Gr impact collar. 125 Gr head. Nocturnal nock, wrap and three Q2iarchery fletches. 286 fps. They shoot pretty well.
I can build a stiffer 250 RIP TKO. 8.9 GPI. 75 Gr insert. All other components the same. 523 Gr total weight.
What is better or more effective, since one is light on FOC and the other is heavy on FOC…..Or does it matter since they’re the same weight flying at the same fps? Thanks all you physics gurus in advance.
Does anyone think giving up accuracy for more FOC is a *good* idea?
Matt, the 250 is a stiffer arrow, what do you mean the Axis is more durable? Thanks!
There is zero reason to excessively front load an arrow setup out of a modern compound bow. None.
I guess what I was hoping to do, going down this rabbit hole, was see if anyone has experience moving to lighter, stiffer shaft, loading up the FOC and see a MEASURABLE difference shooting these two scenarios.
I can very accurately shoot the Axis out to 80-90 yards on the practice range. I have zero complaints……but what if the other arrow offers some advantages??
I wish TBM was still here :)
What varies is the dynamic spine dependent on all the input variables of the applied forces to the shaft.
How does that result in a weaker shaft? Higher FOC might require a stronger shaft.
What most fail to consider is that there are two dynamic spine components; one at launch and one at impact, that are opposite. The higher the FOC, the stiffer the dynamic spine at impact, resulting in less arrow flexion and more efficient transfer of energy through the arrow point. That results in better penetration. A higher FOC arrow properly spined for good arrow launch will necessarily require a stiffer/stronger/heavier shaft, a more stable arrow in flight, and better penetration at impact. What's not to like?
“There is zero reason to excessively front load an arrow setup out of a modern compound bow. None.”
I couldn’t agree more with with both those observations. With your arrow weight and speed, there’s zero need to sweat the minutiae. Pick whichever tunes best out of your bow and go kill things.
Ziek, that was the only thing I was thinking of, driving that new arrow thru my target. I’ll have to see if I can find one 250 RIP TKO and buy just one, set it up and figure it out.
Is it THAT important? I guess that depends on each individual hit. But if there's no downside to improving your odds of turning a bad outcome into a good one, even a little, why wouldn't you?
If I had a 32” DL, I wouldn’t give FOC a second thought. That long a power strike can cure a lot of ills.
1) Easton recommends avg FOC (8-16%)
2) Every single experienced bowhunter I know places low to no priority on FOC.
3) every single pro in every single archery discipline shoots an avg FOC- not one single legit pro shoots uber FOC
Who are you going to believe? Grin
Also I think that wind drift is dependent on arrow profile area and speed and is pretty much independent of FOC.
The best analogy for FOC is how a passenger jet is designed versus a fighter jet
fighter jets need to maneuver and change direction quickly so the center of gravity is more in the middle to pivot on
passenger jets are built with a high FOC and can almost fly themselves and are harder to change course quickly
AS, I bet them arrows fly like a thing of beauty. I love the feeling of a nicely weighted arrow launched via stick n string.. the feed back and trajectory is just… aaaaah
Well, crap. I just found out that I'm not an experienced bowhunter. By the way, the influencers and experienced bowhunters that don't push the "look at me" on FOC push the "look at me" in the opposite direction. I wouldn't follow an experienced bowhunter or archer pro off a cliff either...
If you add weight, then why would you not want it in the part that does the killing?
Feelings bout to get hurt… I guarantee every Olympic archer, or their coach, makes sure they’re heavy up front.. calculated or not I bet it’s over 15%. More likely around 20%
Matt, respectfully, those are irrelevant. It's the ones you hit and didn't recover you should be considering. Of course those are all conjecture. All you can say is 'maybe only if I did this in my seat-up'. Since it's usually impossible to really know what went wrong, I look to the physics to give me ANY possible advantage, no matter how small.
And to be clear, I don't use or promote ridiculously high FOC. The more the better, within reason. It's just too hard to assemble a balanced arrow for the higher speeds of compounds. I try for about 9 gr/# of draw weight for total arrow weight, and 15% or more FOC. And the lower the power of the bow, the more important it becomes. My wife's grains/# and FOC are a bit higher than mine. With other aspects of my choices, mostly BH, both my wife and I get excellent results.
Understood and I should have clarified, I don't have any of those I can think of. Every animal I have hit and lost has been either shot placement or scapula-related. Not one deflection or head scratcher that I can recall. Even the couple of "failures" I have experienced have been BH-related (folded ferrules) but thankfully resulted in recovered animals.
Tim257, right there with you, I said the above but know of a couple of instances where guys tried to get high FOC and keep the total arrow weight down and had shaft failures on impact (presumably due to side force cause by a deflection). One resulted in a really long afternoon but a successful hunt after a follow-up shot (antelope), but a couple resulted in lost animals (elk). Ashby has FOC quite a ways down the list compared to structural integrity (#1) for a reason.
Just my .02. Lee
We already know that shot placement and a durable sharp head are crucial. After that, use enough weight to achieve good momentum for the game hunted. Tune your setup so the arrow travels without wobble & fishtailing. Now for the science part... it matters not where the weight is throughout the arrow as long as the aforementioned items are good. Picture in your mind an arrow falling straight down from above. That arrow will penetrate the same with 10% FOC as it will with 30% FOC. Honest...
A lawn dart comparison, really?
What the very high FOC folks forget is the law of Physics rule of equal and opposite reactions. An arrow is launched under extreme tension. The additional mass on the tip can be a benefit once in flight but its a big destabilizing force on the launch. Put a lawn dart….or one of the soda straws Ashby uses to trick his followers in a bow and see what happens.
I look at it like this; If Ashbys original criteria of 30% + FOC…(edited, 39% was a typo, Ashby original paper on FOC was a “Threshold of 30% plus) or even over 20%FOC was better, every single pro would be using it…and Easton would be all over it. Nope, not a one.
If you think it works for you, then great.
Frank Pearson my occasional mentor was a champion back some time ago. (His wife Becky was also).They call it NFAA or something, not 3D. He got arrows by the case from Easton, a sponsor.
Anyway he'd just got back from South Africa where he won a 100 meter special contest. He was showing me the trophy. We were in his shop at his home in Vail, Arizona. I think Ulmer was there also.
Anyway (ramble, ramble)..I asked him what his FOC was on his arrows. He had never checked them, he just tuned for good flight.
We checked them out of curiosity and ....... they were a little less than 2.5%. Truth.
I think over the years my hunting arrows ran from 6.5% to 11% depending on my setup. 3D likely 4% to 6%
No point in post, just felt like rambling. ;)
I guess I was more interested to see if the two arrows would react the same……..since one is 300 spine and the the other is a 250 spine with 50 Gr more upfront…..effectively creating a similar effect…..but I was hoping a physics guy would chime in. :)
I’m seeing it as the arrows will react similarly. But the 250 might be more effective at lots of the stuff already mentioned. But I have to find a place I can buy one 250……and that’s more difficult than one can believe.
Blood (OP) - "physics guys" have chimed in, take it for what it's worth.
I shoot FMJ 300, 28 1/4" with 14.9 % FOC without even trying very hard. 150 gr. BH + 16 gr. outsert.
My wife shoots FMJ 500, 25 1/4" with 16.8 % FOC with 125 gr. BH + 20 gr. outsert.
125 gr. up front is really pretty light if you're shooting over 60#.
Based on sales across the industry, 125 gr. is on the heavy side regardless of draw weight. Looking at Lancaster Archery as one example, they list 63 125 gr. BH's, 61 100's, and only 12 150's. Volumes by SKU would only further demonstrate that.
Shooting a 150 gr, head essentially means you are trying hard just be virtue of deviation from the mean/mode in terms of head weight.
Maybe some people just like a little more steel in their broadheads. Not a bad strategy.
I like a heavier broadhead for the extra steel in it. I don’t think it does anything for penetration out of a modern compound. Because of my reasoning in my first paragraph.
However, I do believe it helps penetration with finger shot trad bows. Because fingers do funky things versus a release on a compound. But, in my opinion, there is a point that shows no benefit to extra upfront weight.
One of the better traditional bow shooters ever born is Rick Barbee. He’s tinkered with this stuff long before Ashby put out his “report”. He’s got a long draw and shoots 65-70 pound trad bows even at close to 70 or more years old. His findings were in contradiction to Ashby’s extreme foc.
Rick claims anything over 18-19% is no benefit for penetration. Or accuracy. I see no reason to doubt him. Especially after watching him shoot out candles at 60 yards in the dark. Or, tennis balls at 90 yards during daylight practice. Since most sponsored bow shooters I know in the compound world are looking for the 13-14% foc, I’m guessing there’s merit to the idea that it has its place for both. I just don’t think it’s a huge issue in the realm of modern compounds.
Am I right? I do not know. But, after shooting quite a bit of stuff with both trad bows and compounds, it’d take a lot to convince me I’m not. Or, I’d have to want to research it more then watching this paint dry. That’s about how important I think it is for a modern compound setup.
That being said; if you are not actually recording your own data, then you are a fool if you are not paying attention to Ashby’s actual data.
The ridiculousness of that recommendation should be obvious to all of us.
Let’s just hope that you don’t have a splintered carbon shaft run through the back of your hand with that set up.
Since unbalanced forces on a projectile will cause it to rotate about its centre of gravity, the position of that centre of gravity is important. Increased FOC moves the cog forward causing two effects - both of which are positive on arrow flight. Consider the forces at the fletch and the broadhead during flight. Increasing the distance between the fletch and the cog creates a longer lever arm for the ‘good’ torque. At the same time the lever arm between cog and the broadhead is decreased, lessening the effect of the ‘bad’ torque due to forces applied to the blades.
I believe that moving the cog forward (aka foc) creates a more stable projectile. However, as with most things, pursuing the extreme will reveal real world drawbacks. If you are chasing higher FOC by using a light shaft that is not able to handle the launch or the landing, that makes no sense.
I have added about 100 grains to my ‘22 hunting arrows for a total of 550g. Most of the added weight is up front, but I had to beef up the shaft as well, for adequate spine. Completely unscientific findings here, but I believe that ease of tuning and forgiveness with a bh is better now than before. Admittedly, there are lots of variables in this equation - an obvious one is the fact that I’ve given up some speed, which would also deliver benefits in bh forgiveness (at the expense of trajectory).
You are overlooking something.
The whole reason we tune our set ups is because arrows flex upon release when the string starts pushing and the nock starts moving…. before the head does. But arrows also flex upon impact, when the head slows/stops moving before the nock end does.
When you hit something soft like flesh or maybe a rib, that amount of flex on impact remains pretty trivial, because the arrow doesn’t slow down that much on a rib. At least not with a conventional BH. A big mechanical that’s confronting two or three or four ribs…. There’s a reason that there is usually a KE minimum recommendation with those, right?
So I’m pretty sure that most people assume that flex upon impact doesn’t really matter. A lot of people probably don’t even entertain the possibility that it happens at all.
But if you do the math… Let’s say an arrow flexes to a deflection of X at launch, during which the acceleration goes from 0 to max on a power stroke of 21”. If you hit something hard and get 7” of penetration, the arrow is stopping in 1/3 the distance, so the point is applying roughly 3 times the force that the nock did. If you take out FOC and lever arm considerations, I’m going to guess that the deflection would then be 3X.
In reality it would be nowhere near that clean, of course, because of velocity lost to drag through the air and friction applied to the shaft in the target medium, but I think the basic premise is sound.
When you load up an arrow with high FOC, you need to go with a stiffer shaft, because force applied at the nock end has a longer lever to use to flex the shaft to the necessary degree. High FOC arrows also tend to be made from lighter shaft materials (because for a given total arrow mass, there is no alternative).
Anyway… I have this crackpot theory that when an arrow flexes upon impact, the nock end will travel off of the axis of flight and basically begins to overtake the point by passing on the outside, creating a lateral force. And it’s really not so far-fetched, because many years ago I saw a video where someone was trying to prove how tough their broadheads were, so they shot them into beef bones and filmed the impacts at a very high number of frames per second. And what you could see very clearly in the video was that upon impact, the point would stop moving, and the nock end would wrap/bend all the way around until it snapped the arrow. So clearly a very large amount of force was redirected from the task of penetrating straight on through the target and ended up being used to do nothing more than destroy the arrow. I don’t think that’s a good thing in a hunting arrow.
And the lighter and stiffer the shaft material, the less potential there is for that to happen, because less nock-end mass will be displaced from the line of travel, and there will be a stiffer shaft in place to control its movement. If you could come up with an infinitely light, infinitely stiff shaft (and somehow get it to tune), it wouldn’t happen, but it does.
Then the other thing is… As someone mentioned up above, that longer lever acts as a force multiplier for the fletching that you have on there, which helps to straighten up your arrow quickly and keep the nock end perfectly aligned behind the point throughout flight and on impact, thereby lessening the potential for that lateral force to develop in the first place.
Because if you think about dropping a 2 x 4 from some considerable height onto a cement floor, if it lands plumb, it’s going to bounce pretty high. Maybe more than once. But if it were to strike at say 3° or 5° (or more) off of vertical, it would slap the floor a lot quicker and a lot harder. You don’t want that on a deer.
So I suppose I’m rambling a bit here, but you get the idea. There are a lot of reasons related to the physics of an impact which support the idea that a high FOC arrow should penetrate better than an old-fashioned arrow.
How much difference those things make when nothing very solid is hit probably approaches zero, but if you hit (for example) a shoulder blade… With a big mechanical…
That’s why deploy-on-impact mechanicals don’t make any sense to me. Too much leverage to send the tail of the arrow off line.
If Biden ever creates a Ministry of Penetration, my vote is for Corax.
Edit: oops this was meant for the pet peeve thread.
It was on Facebook last late summer or so.
I tried finding the link but with no luck.
His testing was extensive and proving through all sorts of media and arrows weights.
I’ll keep looking because it’s that good.
Joel did a great job here.
I’m not sure if he posted this info other than on Facebook.
Personally, I like my 525 grain arrow out to 25-30 yards, but that’s it.
Some of you may recall the "have you ever recovered an Elk shot in the scapula" thread from a few years back. I don't recall FOC meaning much, if anything.
There’s a big difference between being FOC conscious and an FOC extremist. Shooting 125gr bh isn’t the norm anymore, hell some bh aren’t even offered in 125. So Bob (I assume) shooting 125 + 15 insert= 140gr you just did an FOC cartwheel, congrats. You could’ve easily made up the weight with an extra inch or 2 of shaft, long wrap, bigger vanes, or even an fmj with an 85gr tip… but instead you put it up front, hmmm. Of course this is speculation bc you did not divulge any detail. Nonetheless.
So for the millionth time for the teenage foc anti-physics rebels, no one is advocating for extreme foc and if someone what’s to experiment why crucify them? Heaven forbid if someone wants to tinker with THEIR rig and discuss it here.
I used to slap an 85gr thunderhead on my 2413, but I wasn’t doing myself any favors when trying to win $$$ on the 150yd (or further??) elk closest to the middle jackpot. We used to aim off the tree line.
With a little extra tuning and tweaking with my bow……
Here’s what I saw between the two arrows. Both fly great in calm conditions. The RIP TKO with higher FOC was more accurate in windy conditions and if I had a poor release……especially this! These were shot out to 100 yards. With a “perfect” release, the higher FOC also hit more accurately at long range…..I would surmise that the arrow is able to stay on course easier with more weight up front……given the factors.
Interestingly, I was able to use the same sight tape. Initially it appeared I’d need a different one (I assumed more drop out at longer distance since the point might “pull” the tip down), but after some adjusting for paper tune, I was able to use the same tape.
I feel more confident in the higher FOC, FPS and weight of this arrow set up. And if it drives straighter through the air….and animal….I think this works better.
Well said Shawn, only time I increase my FOC if I get a deal on 125gr broadheads!
Ever since man was launching sticks in the air foc has been here. Certainly not new by any stretch of your imagination.
With attitudes above its amazing we shoot compounds and these over built factory arrows, who needs proper spined arrows anyway!!.. then choose among 100’s of different bh’s… pffftttt people been killing plenty animals before this stuff came along.
Yes there are guys that CLAIM this….but then do not provide a controlled study to prove it. Its their OBSERVATIONS that they want you to believe.
Last time I checked Archery and bowhunting is a game of accuracy. Following along with all of the most accurate archers in the world makes good sense. So when every experienced bowhunter I know including a couple shop owners…. And every single pro in every Archery discipline Scoffs at EFOC….that should tell you something. Grin
I will go with the experts before I go with a guy that uses rubber bands to prove his ‘theories’ or some guy sprinkling fairy dust on his arrows.
Joel did a great job here.
I’m not sure if he posted this info other than on Facebook.
Mostly those posters are either gone or changed their screen names due to embarrassment. I'm apparently not the only one to get sucked back into that old debate now every time the term FOC comes up.
Truth be told, one has to either be really dumb when buying components or, really have to try hard to make an arrow with less than 10% or more than 20% FOC.
I wouldn't personally consider anything inside those parameters as high or low, just "normal". Which is why I for one automatically think "extreme" when I see the words high or low used.
While shooting the RIP TKO’s I hit some rebar in some targets there and the arrows completely snapped off at the insert. I’ve done this before with the Axis arrows and they don’t snap into pieces….they splinter…..therefore still having the ability to drive the arrow and broadhead into your target.
Still more testing to do….but I’m leaning to go back to the Axis for pure hunting scenario-real life scenarios.