Bowhunting Tech Tip: Arrow Spine vs. Arrow Weight

In this video, LAS TechXpert P.J. Reilly addresses the difference between arrow weight and arrow spine.

An arrow’s spine determines how much the shaft flexes when it leaves a bow. Archers want their arrows to flex some, but not too much.

Arrow weight refers to how much the arrow actually weighs. That weight can change as you look at arrows of different spines, but simply choosing a different arrow spine in order to change your arrow’s weight is not a good idea.

We sometimes see bowhunters opt for weaker arrows when they want to cut arrow weight, or choose stiffer shafts if they want a heavier arrow. Either can cause problems with accuracy, especially if a fixed-blade broadhead is added to the shaft. Such broadheads tend to magnify flight problems.

Lighter arrows fly faster than heavier ones, but heavy arrows generally result in better penetration. Depending on what they’re hunting and where, bowhunters might prefer a heavy arrow or a light one.

Bowhunters choosing an arrow should stick with the spine recommended by the manufacturer. That recommendation will be based on draw weight, arrow length and point weight.

If bowhunters want to change their arrow’s weight, they can opt for heavier or lighter shafts without changing spine. They can also increase or decrease point weight, but then that could affect the manufacturer’s spine recommendation.

Explained: Nock Fit

Professional archer and bowhunter John Dudley, host of the Nock On television show, covers proper nock fit in this third installment of Nocked and Ready to Rock.

Dudley is covering all aspects of finding and shooting the proper arrows in this season’s, 13-part series of Nocked and Ready to Rock.

Having your nock fit correctly on your bowstring is important for arrow accuracy, Dudley explains. If it’s too tight or too loose, accuracy will suffer. Dudley explains how to determine if your nock fits properly, and what to do if it doesn’t.

Explained: Types of Arrow Shafts

John Dudley, in this episode of Nocked and Ready to Rock, explains the most common types of arrow shafts that are on the market today for bowhunters who use compound bows.

This is the first episode of Nocked and Ready to Rock for 2016, and Dudley’s plan for the entire series is to explain how he picks, builds and tunes his arrows for bowhunting. The full series includes 13 episodes, which are part of Dudley’s larger television show, Nock On, aired on The Sportsman Channel.

In this first installment, Dudley talks about aluminum arrows, carbon arrows, aluminum/carbon arrows and others. He also offers explanations of the benefits of each type.

A basic guide to arrow nocks

It was in 1991 that the “Iceman” was discovered by hikers high up in the Italian Alps near the border with Austria.

Among the artifacts recovered alongside his mummified corpse were an unfinished longbow, a quiver and a handful of arrows, only two of which were ready to be shot. They had leaf-shaped flint heads held in place within a notch by wood pitch and sinew; three trimmed feathers for fletchings; and notches cut into the back end to receive the bowstring.

So archers have been using nocks of some fashion for more than 5,000 years, because the Iceman is believed to have died 5,300 years ago. Today, arrow nocks are much more sophisticated, but they still serve the same purpose.

PRESS-FIT NOCKS

Press-fit nocks arguably are the most common nock today, as they are used with nearly all but the skinniest carbon shafts. They’re also used with many aluminum shafts, too. As the category name implies, to install a press-fit nock, you simply slide the nock post inside the arrow shaft, and press down until the shaft end contacts the actual nock.

 

insert nock

 

No glue is required with press-fit nocks. You just stick them in, and pull them out, as needed.

They are completely indexable, which means you can turn them to any position to align properly with your fletchings and to achieve rest and/or cable clearance for your fletchings.

With press-fit nocks, it’s critical to know what shaft you’re shooting, since not all shafts have the same inside diameter. Naturally, all arrow manufacturers make nocks to fit their arrows. Aftermarket press-fit nocks bear the common sizes G, F, X, A, H, S and GT.

G and F nocks fit shafts with a .166-inch inside diameter.

X and A nocks fit shafts with a .204-inch inside diameter.

H and H.E. nocks fit shafts with a .234-inch inside diameter.

S nocks ‑ also called Super Nocks ‑ fit shafts with a .244-inch inside diameter.

GT nocks fit shafts with a .246-inch inside diameter.

Some archers will put aluminum Uni-bushings into the nock ends of their arrows in order to help protect the shafts from being damaged by other arrows. They then must find press-fit nocks that fit those bushings.

Also, bowhunters use certain press-fit nocks with battery-powered lights inside that light up when an arrow is released. The lighted nocks help bowhunters recover game and/or their arrows in poor light.

PIN NOCKS

Pin nocks are tiny nocks that fit onto an aluminum pin that’s installed into the nock end of the shaft. The pin bushings are meant to protect shafts from being damaged by other arrows. Any nock labeled as a “pin” nock will fit any pin insert, since all pins are a standard size.

pin nock

Pin nocks are popular among competition archers, who shoot expensive shafts they don’t want to get damaged. Also, target archers believe the smaller, more fragile pin nocks tend to be more accurate and they minimize deflections of their own arrows, which could result in an arrow getting pushed into a lesser scoring ring.

OVERNOCKS

The overnocks are those attached to an arrow by sliding the arrow inside the nock. The nock fits over top of the shaft.

overnock

Overnocks are most commonly used with carbon arrows and they come in nearly two dozen sizes to fit a host of shafts. They’re also used with shafts made of other materials. Easton’s X10 Overnock, for example, can be used with the company’s X10 aluminum/carbon shafts.

CONVENTIONAL NOCKS

These nocks are used on aluminum arrows with the cone-shaped back ends, called the swage. They come in several sizes which correlate to shaft diameters. You can simply press these nocks into place and tighten by hand, or you can lock them in place with a non-cyanoacrylate glue.

conventional nock

GROOVE SIZING

Some other nock references you need to be aware of are “small groove” and “large groove” sizings. The groove is the opening between the nock posts or ears. The small-groove nocks are meant for the skinnier bowstrings, like you’d find on low-poundage recurve bows. The large-groove nocks are meant for compound bows and for recurves with thicker strings.

You want your nock to make an audible click when you seat the nock on the bowstring. Usually, you’ll only hear that click when the nock fits perfectly. You don’t want your nock to be too tight or too loose on the string.

CROSSBOW NOCKS

Crossbow nocks, obviously, are the nocks used with crossbow bolts. There’s the flat nock, the half-moon, the Omni-Nock – which features six micro-grooves that form three bowstring channels – and the Capture nock – which closely resembles a traditional arrow nock.

crossbow nocks

From left, flat nock, capture nock, Omni-Nock and half-moon nock.

Different crossbow manufacturers recommend different nocks for their bows. Check to see which one is recommended for the bow you’re shooting.

The nock is the critical connection between your arrow and the bowstring. Know which one you need to get the job done right.

Easton X10 Arrow Shaft

The Easton X10 arrow shaft is reviewed in this video by Lancaster Archery TechXPert Randy Groff. The X10 has claimed more world title and Olympic medals than any other arrow on the market.

Made of carbon, with an aluminum core, the X10 has a unique barrel shape, with tapered ends extending out from the fattest part of the arrow in the middle. This design makes the X10 ideal for slicing through wind. That’s critical for archers shooting targets in competitions as far away as 90 meters.

The X10 comes in 14 shaft spines, ranging from 325-1000.

G5 Arrow Squaring Device

Lancaster Archery Supply TechXPert Randy Groff demonstrates how to use the G5 Arrow Squaring Device. This is a tool that can be used to make sure that the ends of your aluminum or carbon arrow shafts are perfectly square. If they aren’t, you can have problems with erratic arrow flight.

Basically, you set your arrow in the squaring device, with the shaft end that’s being squared pressed against the grinding butt. Spin the shaft with your hand, and the grinding part of the tool will remove material to make the shaft end square.

The grinding butt has one side that’s used for carbon arrows, and another that’s intended for aluminum.

Paper tuning 101

Straight as an arrow.

It’s a saying that’s used beyond archery, but archery is its root.

Achieving perfect arrow flight, or, getting your arrows to fly as “straight as an arrow,” should be the goal of every archer. If your arrow flight is true, then the sky’s the limit for accuracy.

Paper tuning is one of the most common ways compound archers using mechanical releases determine whether their arrows are leaving their bows in a straight line.

(Shooting a compound bow with fingers is more like shooting a recurve bow, and Lancaster Archery Supply recommends bare-shaft tuning in such cases. That’s a topic for another day.)

Through paper tuning you can determine that your arrow rest, bowstring and nocking point are all perfectly aligned, and that you are shooting the proper arrows for your setup. It also lets you know if your hand position on the bow and your shooting form are both correct.

So what you’ll need to paper tune is your bow and some arrows, a frame that can hold paper for you to shoot through, a target backstop and a shooting range.

Your frame needs to hold the paper by all four corners, so it is rigid when you shoot through it. And the frame needs to be positioned high enough that you can shoot straight through it. You don’t want to shoot at a steep angle up or down.

There’s a do-it-yourself paper tuning kit made by .30-06 Outdoors that provides a frame and paper to shoot through. All you have to do is set it on a stand holding the paper at roughly chest height.

Place your target backstop 4-6 feet beyond the paper, so the arrow can pass all the way through the paper before it hits the target. You should stand about 6 feet away from the paper.

 

papertune5 scale

Before you shoot, you must make sure your hand position on the bow grip is correct. Check out this article for information on that subject.

If you are torqueing the bow at the shot, due to improper hand position, none of the bow settings will matter. You will have erratic arrow flight.

Also, you must get a smooth, clean release. Don’t slap the trigger or pull your release hand out to the side. Simply pull straight back through the shot with your release.

So you take a good shot through the paper. What you want to see is a round hole with three or four slices extending out from it – depending on the number of fletchings on your arrow.

If you see that, yell, “Bullet-hole!” and don’t change anything. Your setup is perfect.

papertune3 scale

Short of the bullet hole, what you’ll see is a tear that features a rounded end where the arrow point went through the paper, and a three- or four-slotted hole made by the fletched end of the arrow.

Think about the layout of your tear to figure out how your arrow is flying. If the rounded end is down and the fletched hole is above it, for example, then you know your arrow is flying nose down, with the point below the nock.

papertune2 scale

Nock left tear.

Here’s a list of tears, and the most common remedies for each.

  1. NOCK HIGH – Move your nocking point down, or your rest up.
  2. NOCK LOW – Move your nocking point up, or your rest down.
  3. NOCK RIGHT – Move rest away from the riser on a right-handed bow, toward the riser for a lefty. This tear also can mean your arrow’s spine is too stiff. Switch to an arrow with a weaker spine, or you can increase the point weight on your arrow, which will weaken its spine.
  4. NOCK LEFT – Move rest toward riser for right-handed shooter, away for a lefty. This tear also can mean the arrow’s spine is too weak. Switch to an arrow with a stiffer spine, or reduce your point weight.
To start, the arrow shaft should be level from the nocking point to the shaft.

To start, the arrow shaft should be level from the nocking point to the shaft.

If you’re scratching your head over the fixes to the rest for point-right and point-left tears, know that many archers struggle with solving horizontal tears, because the corrective action is counterintuitive.

Logic would seem to dictate that if the paper tear shows the nock is left of the point – commonly called a nock-left tear – then you should move the rest left, to push the point left. But that’s not the case.

What happens is, the arrow wants to fly in the direction of the string’s travel. So if your rest is too far to the left, the point will kick to the right as it leaves the rest to follow the string path, and your paper hole will show a nock-left tear. Move the rest right to solve the problem.

Now what we’ve listed are common fixes for imperfect tears. If you try the suggested fix and you still get a tear, there could be issues not involving the rest or the nocking point.

Unless you’re shooting a single-cam bow, check the timing of your cams. These cams will have timing marks that allow you to see how they’re rotating. If one is rotating faster than the other, you’ll get paper-tuning tears. To synchronize them, you’ll need a bow press, because you’ll have to twist the cables. Or you can take your bow to your local pro shop and let them fix the problem.

If your arrow is making contact with the rest, that can cause paper-tuning tears. Spray your fletchings with white, aerosol foot powder and then shoot that arrow. If it’s making contact, you’ll see lines in the powder. Rotating the nock often will eliminate the contact problem.

Take three shots through the paper each time you make a setting adjustment. If all three shots show the same paper tears, then you know they’re likely the result of issues with your bow, rather than your form.

papertune1 scale

Arrow spine vs. arrow weight: Don’t be confused

In the Lancaster Archery Supply Pro Shop, we hear it all the time.

“I want to switch to a lighter arrow to get more speed.”

That’s usually not a problem, as long as you don’t confuse arrow weight with arrow spine. Too often, that’s exactly what archers do. Someone shooting a bow with a 70-pound draw weight and a 29-inch draw length will grab a 400-spine arrow to replace the 340-spine arrow they’ve been shooting. They think that’s the right way to reduce arrow weight.

It’s not.

When we talk about an arrow’s spine, we’re talking about how much it flexes. We’re talking about its stiffness. Every arrow should flex when it leaves the bow. But it should only flex a certain amount. If it flexes too much – weak spine – then its flight will be erratic. If it doesn’t flex enough – stiff spine – then the arrow will have no forgiveness. Consistent accuracy usually suffers in either case.

Choosing the correct arrow spine for your setup depends on your draw length and draw weight. Draw length is important, because that determines how long of an arrow you need to shoot. And the longer a shaft is, the more it’s going to flex. Draw weight is factored in, because that determines the amount of force pushing the arrow.

Every arrow manufacturer has a spine-selection chart, so you know which shaft to choose for your draw weight and arrow length. (Some even factor in the bow’s speed rating, since faster bows exert more force on an arrow.) And every shaft bears its manufacturer’s spine rating.

Unfortunately, the numbering system for spine ratings is not uniform from manufacturer to manufacturer. So don’t assume the numbers you see on shafts across manufacturers are comparable.

Beside or below the spine rating, most shafts usually also are stamped with their weight in grains per inch. And this is where archers can get confused.

Let’s take the Easton Bowfire, for example. The 330 shaft weighs 9.6 grains per inch. The 400 shaft weighs 8.5 grains per inch. Logic might tell an archer that, in order to lighten their arrows, they should switch from a 330 to a 400. Bad move. The 400 arrow is lighter, but it’s also weaker, and so tuning could be a real problem.

If you want a lighter arrow, stick with the recommended spine rating, but switch to a lighter shaft. Again, that 330 Bowfire shaft weighs 9.6 grains per inch. A 330 Easton Hexx, however, weighs 7.9 grains per inch. Same spine – lighter shaft.

Just for comparison, take a look at these arrows. All measure 29 inches from the insert-end to the bottom of the nock throat. All include 100-grain points, and three Blazer, 2-inch vanes. And all are the correct spine for the archer shooting a 70-pound bow, according to the manufacturer’s chart.

Shaft                                Weight

340 Easton Full Metal Jacket     482.2 grains

330 Easton Bowfire              433.6 grains

330 Easton Hexx                 382.1 grains

So you can see here, there are opportunities to change the weight of the arrow, without deviating from the spine chart.