New Pro Chrono velocity results

My son got a new Pro Chrono this past week and the first rounds tested were Rem, Golden bullet 22's. From a Buckmark pistol they were all over the place from 950 to 1058 fps. No surprise they don't shoot well. Next was my 45 ACP and my handloads with 200 gr. cast over 6 gr. SR 7625. These were consistent @ 950-960 fps. I checked two reloading manuals and Lyman's 45th edition shows max load of 6.2 gr for 864 fps. Speer shows 932 fps for the same load with jacketed 200 gr. HP. I have never considered this 6 gr. load as hot for our guns and was surprised by the extra velocity with .2 gr. less powder. Just wonder if the readings can be correct.
My bad, I didn't know he fired another load. These ran where they should, 885-914 fps.

Last edited by DLCTEX; Today at 02:48 PM.

Boolit Buddy Join DateFeb 2011LocationBredasdorp South AfricaPosts61

DLCTEX, living South Africa, I would not know much about your loads since we do not get SR 7625 over here, however one would expect that with your load of 6.0 gr that you should be in the 850 f/sec region? I have been shooting 200gr boolits in my 1911's for more than 30 years now, and to get them up to 1000 f/sec is pretty stiff.
Be that as it may, as far as your chronograph readings are concerned, if you place the chronograph in direct sunlight you could get readings with 100 f/sec offset to when you put it in the shade. It is best to put it in shade, constant lighting is very important for accurate/consistent readings....maybe this could be part of your problem?

Cronographs measure the light change over the sensors. Besides the bullet, it can sometimes catch the muzzle blast's pressure wave front as it passes over. The easiest way to avoid this is to move the Crono back a bit.

Boolit Buddy Join DateMar 2013Posts53

i have that same chrony, if it is facing the sun it can give screwy results...

My bad, I didn't know he shot another load. Reviewing the correct group of readings put the velocity right where it belongs, 885 -914 fps.

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Abbreviations used in Reloading
Pointed Soft Point "Core Lokt"

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