Discussion Forums

James Pigott

Hello everyone:

It’s been a few years since I’ve posted on here. I performed a quick query of the forum and didn’t find a similar topic, so, here goes! Apologies if I missed this topic elsewhere.

I have been using a Shooting Chrony Alpha for around 10 years now. I’ve always been highly suspect of chronographs of this type since it essentially works by measuring the fraction of time of the shadow of the bullet as it passes over the two sensors. Lots of factors from muzzle blast, direction, and orientation of the sun, distance from muzzle, and percent cloud cover (all noted in manual) play important roles in how well the unit works.

I was using my Alpha yesterday to get a feel for two hand loads I had developed for two Tikkas (7mmRM and .300 WM) and noted that the loads were suspiciously low in velocity in comparison to what I thought I might have been getting…

7mmRM: 162 Hornady BTSP with 69.5gr of IMR 7977 @ 2,750 (book says potential for 2,950 with 24” barrel)

.300 WM: 200 Hornady ELDX with 74.4gr of IMR 7977 @ 2,700 (book says potential for 2,850 from 24” barrel)

I was prepared to accept that the barrels may be “slow” or the loads at least underperforming from the velocity spectrum until I noted the extreme spread in velocity. I was getting 70+FPS spread with the 7mm and 100+ with the .300… The 7mm is the most accurate rife I’ve ever owned and will shoot 3/8” of an inch if I’m REALLY doing my part and the .300 will group 1/2” regularly.

So, it lead me to believe that my chronograph may need calibration or perhaps the sun was really causing problems yesterday. Granted, it was partly cloudy which could of caused the dispersion in data, but I wouldn’t of thought it was that dramatic. Perhaps it is the load… However, they have proven to be nothing but consistent.

Now that I’ve taken care of the background so to speak. I would like to invest in a new chronograph that might be less sensitive to ambient light and potentially more accurate. I really like the idea of using a chronograph as a diagnostic tool.

I am considering the Magnetospeed V3 or a Lab Radar. They both have their strengths and weaknesses.

My real only concern with the Magnetospeed V3 is that since it is clamped to the barrel, it seems like that will drastically change barrel harmonics. Sure, it’s no big deal to do a final sight in after a load is found that meets your criteria… But is there potential to find a load that shoots well with the Magnetospeed V3 attached and then find that after removal the harmonics have changed so much as to not carryover the accuracy you saw, or vice versa?

Any thoughts, tips, or suggestions are much appreciate!

Thanks,

Drew