Barrel mounted, electromagnetic chronograph

[walker2713]

1" on the 6br, and I also used it on a Cooper model 21 in 17 Fireball, which was .80...

 

[TheSnake]

So I take it that this thing is made of some sort of plastic. Looking at the high speed still shots on the web site, you can see the hot gasses and probably flames hitting the read sensor and base. I wonder how many shots it will take before this thing starts to get damaged from the heat?

George, do you see any signs of this happening on yours?

 

[amlevin]

So I take it that this thing is made of some sort of plastic. Looking at the high speed still shots on the web site, you can see the hot gasses and probably flames hitting the read sensor and base. I wonder how many shots it will take before this thing starts to get damaged from the heat?

George, do you see any signs of this happening on yours?

"Plastic" isn't like it used to be. Far more heat and impact resistant than that of the past.

The preferred term today, especially in the gun world is "Polymer". They even make firearms out of it 8).

 

[jlow]

Thanks for the test and report – much appreciated.

I guess one objection I have seen to the barrel mounting system is that it touches the barrel and as a result potentially may have effects on the POI and accuracy of the gun. Realize that you are only doing load development at this point but a comparison between groups with and without the system mounted might be useful down the road when more finalized loads are available?

 

[walker2713]

jlow: good point.....and I'm planning on doing that test on my next trip to the range....probably tomorrow.

I'm going to load 30 rounds with 30.6gr of CFE223, and shoot three five shot strings with the bayo attached, and the same without.....we'll see.

TheSnake: it still looks new...no apparent wear or damage, though of course it's only had 60 rounds fired over it....

George

 

[jlow]

Thanks walker2713! Looking forward to you test results!

 

[walker2713]

Here's my follow up report on accuracy with the Magnetospeed chronograph:

i loaded 30 6BR rounds with 30.6gr of CFE223, and fired 15 rds with the Magnetospeed bayo device on the barrel, and 15 rds without it. In between, I cleaned the barrel and allowed it to cool off, and then fired a fouler. These rounds were fired at 100 yards.

Here are photos of the targets, and most of the information is self explanatory. I have no (good, i.e. exculpatory :-[) explanation for group #2 on the first target....wish I did.

You will all draw your own conclusions based on what you see, but I don't see any evidence that having the chrono gizmo hanging on the end of the barrel made any difference in the accuracy.

(In responding to a question on the Saubier forum, the small caliber folks, the question was raised about whether it would "see" .17 caliber bullets, since some folks had trouble with their skyscreen chonographs with them, especially if lighting was not the best. I fired 10 rounds of .17 Fireball 25gr Vmaxs with the Magnetospeed, and they all registered normally.)

Comments and questions are welcome. George

 

[jlow]

Thanks for the test and results – looks good to me!

A bad group happens, but I too don’t see any evidence of an effect of hanging the electromagnetic chrono off the barrel on accuracy.

 

[Scotsman1]

Thanks for your work between setup and all the posting. Its been really helpful. I know I hate to crony because of all the setup BS we gotta go through.

Really appreciated.
BTW, how do you like the new CFE223? I mean overall... Have ya tried it in anything else other than 6BR and 30?

Cheers,
Sean

 

[Nomad47]

George, was there a POI shift or did you make a scope adjustment between the two sets of groups? Or just change aiming point?

 

[walker2713]

I adjusted the scope between sequences....had been shooting earlier at 200 yards, so after I finished strings 1-3, I brought it down 8 clicks.

Good question....glad you asked.

 

[Nomad47]

Thanks, George. I'm leaning toward a change - Shooting Chrony now. I was concerned about POI shift and changes in groups.

 

[amlevin]

I have no (good, i.e. exculpatory :-[) explanation for group #2 on the first target....wish I did.

Just blame it on "Wind Shear". Especially the nasty form where there is a sudden vertical wind : 8)

Hey, if it can happen at airports, it can happen on ranges 8) 8)

 

[Steve Blair]

It does happen at South Bay Rod & Gun Club range. We have large dips between berms, surrounding hills and winds from random directions. That's my story and I'm sticking to it.

 

[amlevin]

I know I hate to crony because of all the setup BS we gotta go through.

I used to hate it too. Then I got a cheap Laser Bore Sighter. Makes setup quick, easy, and no more guessing how much allowance to make for Scope Height. As for steadying the tripod, a bungee cord and a sandbag or bag of #7-1/2 Birdshot does a fine job.

 

[amlevin]

It does happen at South Bay Rod & Gun Club range. We have large dips between berms, surrounding hills and winds from random directions. That's my story and I'm sticking to it.

Ditto at the Kenmore, WA range. It's not unusual to see the wind flags pointing every direction possible at the same time. No two at the same direction at the same time. Makes for long periods of silence followed by a "barrage", then silence again.

 

[Heavies]

The other reports claim a POI shift ~1-1.5" (higher elevation). You didn't see that shift in your test?
I have one on back order. I hope it will be more convenient and better than the shooting chrony I have now.

 

[walker2713]

Yes...I've definitely found that shift in POI.......but since I'm aware of it, I know how to easily and quickly compensate when I remove the device.

For me, it's not something to be alarmed about...just something to be aware of and take into consideration.....

YMMV,

George

 

[Erik Cortina]

Am I the only one that sees the difference in accuracy between the two targets?

 

[memilanuk]

Must be you, Erik.

Add up the numbers and do the math. A little over 0.050" difference between the average group size between 'with' and 'without'... which considering the small sample size and the group sizes to begin with... is basically just 'noise' and could have gone either way.

Do I plan on shooting an entire F-Class string with one strapped on my barrel... probably not. But considering the PITA I have getting reliable consistent velocity strings with conventional chronographs 'up here', I'm certainly willing to be a little more open minded.

Monte