Downrange Speed Sight-In Method

This document details the Downrange Speed sight-in method. This method is extremely precise and is not reliant on accurate user-supplied sight marks.

The Data We Need

Density Altitude

Ranges

These are the ranges you will measure arrow speeds at. Assuming a precise chronograph like a Lab Radar or Garmin Xero, the choice here hasn't seemed to be too critical.

With the Lab Radar, we like using 20-60. With the Garmin Xero, we like using 0-60+. In any case, the results using a variety of ranges have been virtually identical in our testing.

Downrange Speeds

These are simply the speeds of your arrow at the ranges specified above.

Reference Mark (optional)

If you are shooting a 'target sight' that has a built in reference scale / click system, you can choose to enter a reference mark for a distance of your choosing. You can think of this like a 'zero' that we use to calculate marks for other distances. This shot-in reference mark should be at a reasonably far distance to minimize error.

Tips for Gathering Downrange Speed Data

For both the Lab Radar and the Garmin, we follow manufacturer instructions for configuring the settings of the units for archery equipment.

Which chronograph should I choose?

That's a tough call.

The Lab Radar is quicker for this purpose specifically, as it can gather speeds at multiple distances in one shot. It's also a bit less expensive than the Garmin Xero.

However, it's bulky, the interface and app is a bit clunky, and it requires an external microphone clamped to your bow to consistently pick up shots.

Tip

Lab Radar was kind enough to provide Precision Cut Archery users with 15% off the Lab Radar V1 and accessories from https://buymylabradar.com. Use code PCA at checkout.

The Garmin Xero is much smaller and user friendly. However, it does require that you place it downrange to shoot over the top of it. This can be a bit of a pain if going through this process a lot. Not to mention, somewhat risky to fling arrows over the top of your expensive chronograph. We always recommend putting a target or some other kind of 'shield' in front of the chronograph to protect it from errant shots.

BowBars Archery LLC has made some great 'shields' for the Garmin Xero that are available here. These mount to any tripod, are built out of 1/4" steel, and have a QD system for the Garmin Xero. We highly recommend these if you're going to be using the Garmin Xero for this purpose.

Warning

Precision Cut Archery and BowBars Archery LLC are not responsible for any damages caused by using these products or gathering downrange arrow speeds. Proceed at your own risk.

Entering the Data

Here's what it looks like to configure a setup with the Downrange Speed sight-in method:

Validating the Sight-In

Once you've entered your data, the easiest way to validate is to print out a sight tape or mark sheet and shoot it in at the range.

Tip

When putting a fresh tape on your sight, we always recommend 'zeroing' your tape as far as possible, setting your indicator on your tape once that distance is hitting, and then working your way in from there to validate the closer marks. If you set your indicator at 20 or 30 and then work your way out, there's a high likelihood that there's some error in this closer mark that will show up as you move to father distances.