CHRONOGRAPH USE

 

QUESTION:
I currently load 82 grains of S341 powder in my .375 H&H Magnum behind a 200 grain jacketed flat nose bullet. I am trying to find a long range bullet and load for the .375. I know that you manufacture a 200 grain boat tail bullet in .375 cal. Do you manufacture a V.L.D. bullet in this caliber? What do you think of my load? There is no indication of pressure such as flattened primers and difficult extraction etc.

ANSWER:
Your load sounds pretty reasonable. It is probably not a maximum load, but on the high side of the range. Without having chronographed the load, there is no way of saying what it is really doing. I would guess that the velocity is somewhere between 3050 fps and 3150 fps. A lot depends on barrel length, chamber and bore tightness or looseness and the only way to be sure is to chrono the loads. Try to find someone with a good chronograph to help.

QUESTION:
I purchased a box of your 400 grain 458 HP bullets. Yesterday I took my ****** chronograph to the range and, with the first six loads of Somchem 321, obtained the following results:

78 grains - 2375 and 2293 fps
79 grains - 2369 and 2681 fps!!
80 grains - 2757 and 2738 fps !!!!!!

How is this possible? There are no signs of pressure and even recoil seems less than factory ammunition. The rifle is a Winchester m70 with a 21 inch barrel.

ANSWER:
I do not mean to be rude but using the make of chronograph that you have, is about as reliable as taking the temperature of a critically ill patient with the palm of your hand. You can get some sort of idea, but you are never quite sure. Sometimes they work and sometimes they don't.

I have been using Oehler equipment for more than 20 years. For occasional shooters and where a reloader only loads for a couple of firearms, if three or four guys club together, the price of a good quality machine, split three or four ways, is reasonable and results are reliable. At major shooting events we used to set up two Oehler chronographs in tandem, to monitor competitor’s ammunition. Observation of thousands of shots fired in this manner and working with most makes, has convinced me that this is not the place to try and save money. Get a good quality chronograph.

Remember that anything that goes downrange sooner or later gets shot, if you have to get as close as is required with an optical chronograph. With better equipment, only the measuring screens go downrange, and they are easy and economical to repair when they are hit. The problem is that, with current chronographs, the machine measures the passing of the bullet optically and this limits the distance for shooting over it. The window through which one has to shoot is about 300mm high and about 300mm wide at the widest point. This has now changed with the advent of acoustic speed measurement.

A company in Norway, Steinert Sensing Systems, has developed an acoustic chronograph. I have tested this machine and the ease of use, accuracy and reliability makes it worth every cent spent on it.

See this page for more information.

This is a very promising development as it eliminates the possibility of hitting the chronograph when shooting over it. The window of application is huge, compared to any optical chronograph. It is not attached to the firearm in any way and does not interfere with the point of impact when used. Especially important is the elimination of the light dependancy of the machine. It does not matter whether there is cloud cover, whether the sun is up or set, or whether it is indoors or out. The major problem of misread shots has always been that the sensors cannot 'see' the bullet passing. With this chronograph it hears the bullet passing and this is a major step forwards. For air rifles, bows and anything subsonic, this system does not work and the measuring of such would still be dependent on old technology.