How NOT to Ventilate Your Costly Chronograph — Set-UP Tips

“Shooting Chrony” is a product name. “Shooting Chrony” should not describe (post-mortem) what you have been doing to your chronograph. Sooner or later all of us may make a mistake, and ventilate our chronograph. With luck, the bullet just “wings” your chronograph, and the damage is minor. But if you hit the unit smack dab in the middle, you may have to retire your chrono for good.

A while back, Forum member Jeff M. (aka “JRM850″) experienced a “low blow” that put his Shooting Chrony out of commission. With tongue firmly in cheek, Jeff started a Forum thread entitled Chronograph Not Picking Up Shots in Bright Sunlight Anymore. Looking at the photo at top, the problem is obvious — he ventilated his Chrono.

This was Jeff’s first chrono kill in 23 years of use, so we shouldn’t be too critical. Jeff explained: “I didn’t realize a friend was shifting from a 300-yard target to 100 yards.” The agent of destruction was a low-traveling 58gr V-Max running at 3415 fps. What happened? Well, when one is shooting at 300 yards, the trajectory will be higher than at 100 yards. We should say, however, that this may have been a low shot, or the 100-yard aiming point may have been placed lower to the ground (closer to the bottom of the target frame), as compared to the 300-yard aiming point.

Other Forum members offered some sarcastic responses:

Try it on an overcast day – it might work again.

It looks like the V-Max performed just about as advertised.

Aww…a little duct tape and some Super Glue and you’re good to go.

If you are using a LabRadar or Magnetospeed, your chrono shouldn’t be in the line of fire, but for those will conventional chronos, here’s some good advice…

Double Check Your Aim Point and Trajectory BEFORE You Shoot
The lesson learned here is that you should never change targets (or aim points) without checking your bullet’s flight over the chronograph. We like to align the barrel so the bullet exits a good 6-8 inches above the electronics (check your manual for recommended shot height).

In addition, we always boresight the barrel so we can see the actual target through the bore. Then, with gun UNLOADED, bolt removed and action clear, we look back down the barrel so we can see daylight through the bore, with the gun set on solid rests. If you look through the middle of the “V” formed by the sky screen supports and you can’t see light shining through the barrel’s bore, you probably have a set-up problem and you should re-align the rifle.

Use a Test Backer to Confirm Your Bullet Trajectory
You can put tape on the support rods about 6″ up from the unit. This helps you judge the correct vertical height when setting up your rifle on the bags. Another trick is to hang a sheet of paper from the rear skyscreen and then use a laser boresighter to shine a dot on the paper (with the gun planted steady front and rear). This should give you a good idea (within an inch or so) of the bullet’s actual flight path through the “V” over the light sensors. Of course, when using a laser, never look directly at the laser! Instead shine the laser away from you and see where it appears on the paper.

After you have used the laser boresighter to get the rifle centered up in the chrono’s “sweet spot”, confirm with a test shot or two (see photo). Even when using an in-chamber laser boresighter, it is not uncommon for the bullet’s actual point of impact to be different than the laser’s dot location.