Barrel mounted, electromagnetic chronograph

[MarkBlanchard]

Interesting coverage on a new barrel mounted, electromagnetic chronograph for handguns and rifles...

http://www.realguns.com/articles/391.htm

Mark

 

[Steve Blair]

It touches the barrel and is, therefore, a non-starter for me. I shoot groups simultaneously and want the barrel undisturbed. Perhaps if they had a variant that clamped to the bench and could be adjusted to barrel proximity...

 

[Nomad47]

Good point, Steve. I wonder if they have done any "before and after" accuracy tests.

 

[walker2713]

This review at Sniperhide may be of interest. I've ordered one, and will compare it to me CED2.

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=3231447&nt=2&page=1

 

[Erik Cortina]

This review at Sniperhide may be of interest. I've ordered one, and will compare it to me CED2.

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=3231447&nt=2&page=1

Apparently, it also makes your gun shoot so you can go out and win BR matches! 8 shots in less than 2" at 600 yards? He had my attention up to that point!

 

[amlevin]

Definitely eliminates the issue of "Shooting the Chrony" for those that forgot the bore is 1.5-2 inches lower than the center of the scope 8)

 

[Nomad47]

Well, I can't read links to Sniper's Hide (long story), but if Steve & Erik have their doubts, that's good enough for me.

 

[Erik Cortina]

Bill, it looks like a pretty simple design, but like Steve said, I would make I to where it attaches to the shooting table instead of the barrel. Should be easy to do.

Keep in mind that you use muzzle breaks. This thing sits about an inch below the bore, I would think a muzzle break would possibly break it or at least disrupt it enough to create reading errors.

 

[Nomad47]

Thanks, Erik. Their website shows it mounted on a muzzle braked barrel - just behind the brake.
Clamped to a tripod instead of the barrel might work. I would like to know how critical the alignment is and how far from the bullet path it can be and still be accurate.

I like the elimination of sky screens. And I like the concept of very easy alignment. Too bad it has to clamp to the barrel.

 

[walker2713]

My plan is to try it "as is" and then perhaps adapt it to a small camera tripod, so that the "bayonet" sits just beneath and forward of the muzzle, as it is set up to do.

Besides not "shooting the chrony," it would make a huge difference when I'm doing load development work at a public range and it's difficult to get the tripod and sky screens organized properly.

We'll see......

George

 

[Steve Blair]

My plan is to try it "as is" and then perhaps adapt it to a small camera tripod, so that the "bayonet" sits just beneath and forward of the muzzle, as it is set up to do.

[br]
We expect a full report.

 

[Nomad47]

+1 on the full report. I'm interested on any accuracy change when tripod mounted. And if there is any POI or group change with the unit mounted to the barrel.

 

[Doug Humbarger]

I am very courious what the maximum distance below the muzzle it can be. If it could be mounted to a bracket attached to the front of the shooting table that extended forward beneath the muzzle that would be great too.

 

[ThunderDownUnder]

There are a lot of 1 1/4" parallel target barrels in use and it appears as 1" is its limit with the attachment at the moment. It seems to be an unusual distance for setup when you consider the target market uses chronos more than hunters and 1 1/4" barrels are sooooo common!

Ian

 

[Nomad47]

They need to make a model that can be attached to a tripod - with larger sensors that can "read" the bullet from 2" away and are tolerant of some mis-alignment.

 

[Steve Blair]

Magnetic fields are a problem in that regard. Field strength diminishes as approximately the square of the distance. So, as you double the distance from 1" to 2", the field strength is 25% of that at 1". In order to provide the field density needed for detection, power requirements increase. [br]
Light, in contrast, can travel across the universe without energy decrease although it does disperse and exhibit decreased photonic density. [br]
The easy answer is that light is much more forgiving in this regard than magnetic fields. That does not say that extending the field and detection is not possible. There are well known means of shaping magnetic fields to extend their reach.

 

[walker2713]

Well, I promised a report, and this is it. I went to the range this morning with my CED2, and my new Magnetospeed "barrel mounted" chronograph. Here's a photo of my set up...you can see I'm shooting with both chronographs....shooting through the CED2, and the display for each is on the right of the bench. The rifle is a Savage F Class in 6BR, 107gr SMKs, Lapua brass, BR4 primers and H4895 powder.

I fired 6 strings of 5 rounds each, with charges ranging from 27.5 to 28.5. This is my first work with H4895 for the 6BR.

Velocity: the average of the Magnetospeed was consitently above the CED2: avg. +.018%. The average ES for the Magnetospeed was 27, and 21 for the CED2. The SD was 7.27 for the CED2 and 10.5 for the barrel mounted chrono.

Accuracy: shooting at 200 yards, the groups ranged in size from .780 to 1.71, but some of the credit/blame for that should go to your humble reporter. :-[ The bayo mount was very stable on the barrel, and required no adjustment once it was set up.

I've got the Excel spreadsheets for the two chronos reports, and will email them to anyone who PMs or emails me at gtw217@gmail.com.

Overall I was pleased with the unit, but think I'll be doing more "side by side" tests in the future. For whatever reason, I have more confidence in the skyscreen unit....but of course for all I know the bayo mounted unit may be more accurate, or the "real" velocity may be somewhere in between.

Any comments and questions are welcome.

George

 

[Steve Blair]

George, [br]
Thanks for the report. H4895 is my favorite powder in 6BR. I'm sure you will find a good load with it. I would expect to correct ~5-6 fps for bullets of that class from 10' instrumental velocity to muzzle velocity, so that may explain the difference. The SD difference is somewhat puzzling. As you said, more side by side is needed. [br]
Re the H4895: You might try incrementing up a little bit, my loads that gave best results are a little more than yours. If you have them, also try CCI 450 and Wolf/Tula KVB-5.56M primers. Both produce low velocity variation. [br]
Another experiment to try is shooting the same "known good" load with and without the Magnetospeed mounted and see if accuracy, POI, etc. are affected.

 

[memilanuk]

My plan is to try it "as is" and then perhaps adapt it to a small camera tripod, so that the "bayonet" sits just beneath and forward of the muzzle, as it is set up to do.

If you look here at their setup for shooting with a pressure/test barrell... I'm sure an enterprising individual could make one that works from a given bench rest setup...

http://www.magnetospeed.com/pages/custom

I'm *very* interested in the unit personally... between the PITA of setting up a regular tripod mounted chrono - waiting for the line to go cold, setting it up, aligning it, hoping and praying that either the natural light or the IR screens will decide to cooperate this particular day (and hopefully for the whole string), hoping that the wind doesn't come up and start playing havoc with the tripod and screens (such fun when the whole thing blows over mid string)... not to mention having to play 20-flippin-questions with all the lookee-loos.

Something I can strap on the end of the barrel, get my chrono numbers and go home. Heck yeah I'm interested!

 

[Nomad47]

George, what is the diameter of the barrel at the attachment point?