Two-Box Chrono

[adamjmac]

I am very happy to announce that my new product is now officially released.

It is the Two-Box Chrono ! twoboxchrono.com

This is a unique chronograph designed for extreme precision, intended for long range load development where measuring SD accurately is critical to success. Most chronographs introduce significant random error, but by spacing two microphones 15 feet apart the sensors can detect supersonic velocity to +/- 1 fps precision in any environmental condition. Now you can measure bullet speed just as well as you can weigh out your powder charges to the kernel.

I had the idea for this long before the AutoTrickler was invented, back in 2014. Working with Silver Mountain Targets (silvermountaintargets.com), we adapted the microphones and sensing circuit into a two-sensor chronograph, and I have been using it for my own load development since then. I built a handful of prototypes for my shooting buddies but I have always wanted to develop a real product from the concept, but I wanted to wait until I could do it right.

 

[BenPerfected]

Sounds interesting and if it is as helpful as your Auto Trickler you have my attention. How do you see the ease of your chronograph design compared to the LabRadar?
Ben

 

[adamjmac]

Sounds interesting and if it is as helpful as your Auto Trickler you have my attention. How do you see the ease of your chronograph design compared to the LabRadar?
Ben

A lot of thought has gone into ease of setup. Since it's two boxes, it's natural to think twice as much work. Actually it's not, because the orientation of each box doesn't matter. All you need to do is place the two boxes such that they point at the target, and set the correct distance using the cable. You don't need to run back and forth to the rifle repeatedly. As for the Labradar, I'm not sure how sensitive it is to alignment.

 

[Barrel Nut]

What will be result of the guy shooting on the next bench offset only three or four feet from my bench? Will his shots record on my Two Box Chrono?

 

[Willow]

What will be result of the guy shooting on the next bench offset only three or four feet from my bench? Will his shots record on my Two Box Chrono?

You can choose from 2, 6, 10, or 15 foot spacing, measured using marks on the cable itself so the shooter in the lane next to you shouldn't be a problem.

 

[Willow]

Adam, is it safe too assume you will plan a video walkthrough showing the chrono in action? Keen to see it in action at a range.

 

[adamjmac]

I'll do a video sometime in a few weeks. I want to do a good one, at the range showing the setup procedure. There are plenty of tips and tricks I could put in a video as far as setup. "In action" is pretty straightforward - you shoot and it tells you the velocity

 

[adamjmac]

What will be result of the guy shooting on the next bench offset only three or four feet from my bench? Will his shots record on my Two Box Chrono?

It will pick up shots from anywhere nearby, but there's a few ways to deal with that depending on what kind of shooting is going on around you. The manual describes this. The three key points are that all shots are recorded in a list so they won't be overwritten, new shots remain on screen for 5 seconds so you have time to look and see, and bullets not fired directly over the chrono are more sensitive to angle changes so that the average of other people's reported shots are likely to be different than yours and identifiable.

 

[DRNewcomb]

I would assume that one could increase the precision of a chronograph like the CED by making a mounting stick that's 4' long rather than the standard 2' long.

 

[Webster]

I would assume that one could increase the precision of a chronograph like the CED by making a mounting stick that's 4' long rather than the standard 2' long.

Went to Kelby's range Tuesday. Guys are already there for the Super Shoot. Two guys had LabRadar chronographs. It's an extremely niece piece of equipment. Nothing to set up down range. Cost is about $650 for the unit plus a mounting stand. Everything is on the bench. Not affected by sun or other problems.

 

[DRNewcomb]

Went to Kelby's range Tuesday. Guys are already there for the Super Shoot. Two guys had LabRadar chronographs. It's an extremely niece piece of equipment. Nothing to set up down range. Cost is about $650 for the unit plus a mounting stand. Everything is on the bench. Not affected by sun or other problems.

I understand that the LabRadar has lots of advantages for about $500 more than some alternatives. It also has some issues, such as occasionally missing shots and not working very well with small-caliber boat-tail bullets. However, the topic at hand is a chronograph that claims higher precision by extending the baseline of the measurement window. I was only suggesting that others could also play at that game. The first Oehler chronograph I ever used had screens about 6' apart. My current CED has screens about 2' apart. I could replace the spacing bar with one exactly twice as long and just double all the indicated velocities.

 

[JohnKielly]

I read on another forum that you're warned against shooting within a certain distance of other shooters to avoid picking up their shots. How can that be avoided on a crowded range?

 

[adamjmac]

I read on another forum that you're warned against shooting within a certain distance of other shooters to avoid picking up their shots. How can that be avoided on a crowded range?

Each shot will appear on screen for 5 seconds. So as you fire, you can look at the screen and see your shot, or if you fired second, it will soon switch to your shot.

Also, other people's velocities will not be correct since they are way off to the side. It's likely to be 100 fps more or less different than yours. If you determine that your shots are clearly identifiable, then you don't need to record each one as you fire. Just shoot your group, then go back with the remote and write down yours in order.

You can also save everything to memory and go back through the numbers at home.

 

[memilanuk]

@adamjmac Would it work down range for collecting velocity data at the target?

 

[adamjmac]

@adamjmac Would it work down range for collecting velocity data at the target?

Yes

 

[Lou Murdica]

I'm at super shoot and one of the labradar he saw was mine
I ordered his new two box chrono I should have it here next week. I don't like labradar because it's a pain to keep it lined up and Missing a lot of shots. Dose not do 22 center fire or smaller.

 

[micmac]

I'm at super shoot and one of the labradar he saw was mine
I ordered his new two box chrono I should have it here next week. I don't like labradar because it's a pain to keep it lined up and Missing a lot of shots. Dose not do 22 center fire or smaller.

Indeed Labradar is quite pain in the ass to set up and work , had 2 diferent units both had similar issues not to mention the stupid fact that it needs exernal powder pack that could have been integrated.(and that external jack is quite delicate)

Am keeping an eye on this new chrono revievs once peple get their hands on them , so please report your findings.

 

[adamjmac]

I just did some practical alignment tests with the Two-Box Chrono to see what you can expect for absolute accuracy. Because of the 15 foot sight radius, it is reasonable to aim the boxes within 1-2 moa, otherwise it appears crooked. If you place your eye 12 inches behind the rear sight, then the picture is roughly similar to aperture rifle sights.

This means the absolute accuracy will be within 2-4 fps of true velocity. Combined with the 0.5 fps of variation, this chrono is both the most accurate AND precise chrono available.

 

[1K6BRA]

Dear Santa,all I want for Christmas is one of these here newfangled chronographs! And it won't shoot my eye out. I have one of your auto trickler systems combined with the FX 120i, it has actually made Weighing powder charges fun. Thank you so much for coming up with a great idea at a reasonable cost. I am sure the chronograph will be of top-notch quality too...... The savings begins again!

 

[Alexander-M]

Adam,

When shooting prone, as I always do, the muzzle is approximately 8 to 12 inches above the ground, depending whether F-T/R, F-Open, etc. Would this be too close to the bullet path?

Also, how true to parallel do the two boxes need to be to the bullet path? You see, even though the surface from which we shoot prone may be reasonable flat, it is common for the ground in front of the rifle to be anything but flat, and placing the boxes may be a challenge if they need to be relatively flat or be parallel to the bullet path.

Thx!

Alex