Can anyone explain this to me

[DWA]

Neighbor's son has a bow that is shooting right around 40 lbs. I've got a recurve shoot about the same. My arrow weighs around 475 gr with 200 gr up front. His weighs around 275 with an 85 gr point. The pro shop that's the only way to set his bow up to hunt. My question is whats the difference. What really is the deal? They need to sell 85gr broadheads or what? Input appreciated.

[txpitdog]

My guess is the cams are a more efficient use of the same 40lbs and give his bow more velocity.

[Bigdaddy]

Two different arrow spines. The recurve you are trying to break down the spine of your arrow to bend around the riser when released versus his is straight of a rest. Remember there is a lot into matching arrows than the general public realizes. In a nut shell it sounds like the shop did the right thing

[bowhuntntxn]

Pretty sure it is the difference in draw length. You being an adult have a draw length 27" or longer. He being a kid has a draw length of maybe 24" or less. And the difference of time the arrow is on the string during the power stroke makes your bow much more efficient and able to push larger weighted heads through objects.

Short draw your bow to about 22" and see how bad your arrows fly. Then shoot one of his and see how much better it flies.

[DWA]

Two different arrow spines. The recurve you are trying to break down the spine of your arrow to bend around the riser when released versus his is straight of a rest. Remember there is a lot into matching arrows than the general public realizes. In a nut shell it sounds like the shop did the right thing

Excactly. You first choose the weight you want up front then you tune your arrow to the bow. So the spine of the arrow is relative to the pundage of bow and weight forward. Couldn't he jump up in spine weight and add weight up front and do the same thing.

[DWA]

Pretty sure it is the difference in draw length. You being an adult have a draw length 27" or longer. He being a kid has a draw length of maybe 24" or less. And the difference of time the arrow is on the string during the power stroke makes your bow much more efficient and able to push larger weighted heads through objects.

Short draw your bow to about 22" and see how bad your arrows fly. Then shoot one of his and see how much better it flies.

I'll take that answer over the other but if I short draw a recurve I wouldn't be pulling said 40# draw weight and arrows would be too stiff.

[bowhuntntxn]

Excactly. You first choose the weight you want up front then you tune your arrow to the bow. So the spine of the arrow is relative to the pundage of bow and weight forward. Couldn't he jump up in spine weight and add weight up front and do the same thing.

No. If he front loaded weight he would have to shoot a light spine really long to flex it enough to shoot well. With his arrows being so short, any spine stiffer than 500 would be like shooting a stick of rebar with a tip on it.

[bowhuntntxn]

I'll take that answer over the other but if I short draw a recurve I wouldn't be pulling said 40# draw weight

Yes I understand, but the effect would be close to the same. You would be shooting an arrow that is way too heavy and stiff for that short length and weight. Just like if you front load his arrows.

[DWA]

My recurve arrows fly great But are almost full length 500s. By cutting the arrows short right off the bat your already getting the cart before the horse in arrow tuning. If it boils down to its convenient to keep kid arrows short I understand. If it's a speed thing I'll bite on that. Hunting deer it would seem to be the lesser effective choice of the 2. That being said he has killed deer with his bow but penetration has seemed to be a problem.

[Lynn21]

Draw length is the key.

[enewman]

The pro shop did that boy an injustice. That is a light arrow for a 40 lb bow. Penetration will be limited. The less weight you pull the more arrow weight you need to compasate for the lack of the draw weight.

I would have built him an arrow with a 125 gn tip and spine correctly to get total weight around 320 to 350. And limit his killing range to around 15 yards max.

[DWA]

Can u elaborate on how 40# at 24" out of a new kids bow would be less efficient than 40# at 27" out of a center cut laminate recurve.

[DWA]

The pro shop did that boy an injustice. That is a light arrow for a 40 lb bow. Penetration will be limited. The less weight you pull the more arrow weight you need to compasate for the lack of the draw weight.

I would have built him an arrow with a 125 gn tip and spine correctly to get total weight around 320 to 350. And limit his killing range to around 15 yards max.

That's the way my brain sees it but I can't get any real answer why its wrong other than draw lenth.which I don't get because of the more efficient cams. 40# of cotton to me weighs the same as 40# of stone.

[enewman]

Not sure if this is what your asking.

But let's look at his arrow. I'm going to use the bow tech rose for the numbers. So at best say 25 in draw at 40 lbs a 275 gn arrow is shooting 250 fps. Sounds great. But that is 38.2 k.e. And .302 momentum.

Will this kill a deer. Yes with a great placed arrow. And people are doing this all the time.

Now if he was shooting a 350 gn arrow. That puts that bow at 8.75 gn per pound. That bow is gaining in effenecnt. So now the 350 gn arrow is shooting say 230 fps. Now we are at 41.1 k.e. But the momentum is .357 Now we are getting some where.

Now let's look at the 475 gn being shot from a recurve. I'm just guessing numbers. Let's say that arrow is shooting 180 fps. The k.e. Is 34.2. But your momentum is .379.

So looking at the momentum numbers you can see how an heavy arrow even being slower will out penetrate a light faster arrow.

Now when shooting high poundage bows this is not as critical.

When you set up arrows. We don't care anything about k.e. We only care about momentum. And that comes from the weight of arrow and speed.

This is why if shooting low pound bows it's important to get the correct arrow set up.

[DWA]

That's exactly what I'm asking and what your saying is the only thing that makes sense to me. So then why are these"pros" setting up young hunters with these super light arrows