I have had a Chronograph for over 12 months and just started to use it. I bought it at a time of affluence; sadly no longer the case.
With the varying velocities I can clearly see the consistancy of my handloads. Apart from this I would like to know how to get the most from the instrument but there doesn't appear to be anything in print that tells me the benefits of such information as standard deviation, Hi, Lo etc. Can anyone help?

Its just a tool to help develope you loads.
avg velocity:
min. velocity and max velocity
the rest of that is made for the number crunches.
one benifit is you will have real world velocities from the rifle load that you test and not a guess.
I like to use the chrono for developing loads on a latter method work up at a range not less than 300 yards.
it helps to have real muzzle velocities to plug into a ballistic progran and get down range velocities say for 600 or 1000 yards
if you are trying diffrent powders working up loads using a latter method sometimes you will find a combination where there is actually a velocity drop with in a load range.
all stated is what benifits me using the chrono.

You havent wasted your money!

Low spread of velocities tells you that your handloads (or factory loads!) are consistent which aids accuracy.

The velocity also tells you if you are on right track with load but dont necessarily aim for top speed.

For me the greatest use is in working out the trajectory and point blank range, zero range and similar.

Have a look at www.exteriorballistics.com and you will soon see why you need that chrono.

As other posters have stated, my chronographs give me actual velocities of my handloads which permit me to calculate point blank range and adjust for POI at various ranges. Beyond that, they permit me to assess the consistency of my handloads, which identifies which particular loads show the greatest promise for future development. Many loads give great consistency, though the groups are not what I might expect. However, if the load is consistent, I know that addressing seating depth, for instance, may well give me the accuracy that I would otherwise expect.

For most of us, the chronograph is also the best tool we have for assessing pressure.

If, with given components, a particular reloading manual has a certain velocity listed at a certain pressure, you can more easily determine where your load's pressure is relative to the published velocity (with the same components, of course.)

I know, I know... it's not exact, but it's no secret that it takes a certain amount of pressure to reach a certain velocity, and for close approximations of pressure, the chronograph is an excellent tool.

I own and use a chronograph and have for years. However, since reading up on the subject of Standard deviation and how it can be calculated, the number of samples to make the calculation valid and etc.... I have lost quite a bit of enthusiasm for that particular datum.

Many casual users of chronographs find that they get a lot of unexpected variation in data no matter how carefully the aim through the sensor field or how accurately they build their ammunition. Assuming the aforementioned is all done and correct, you can and probably do have variations in your data caused by hot gasses that precede the bullet into the sensor field and/or odd readings caused by muzzle flash. I've been told that the main problem with two sensor chronographs is that it is possible to shoot through one field squarely and the other field only marginally, but still get a (allegedly erroneous) reading. It is also alleged that most users do not clean the sensors after each session.

The folks who collect velocity data to be used in powder and bullet makers' manuals use blast screens to help eliminate errors caused by these problems. Some of us at a local club made a blast screen and used it for a while until the club honchos decided it was something they would not care to assume liability for in case of some sort of ????disaster??? Anyway, it did seem to cause more consistent reading on two chronos we used.

These days I only set mine up if I am having unexplained flyers problems with a load that looks good otherwise. Oddly, the flier is not always the round with a big difference in velocity.

The exterior ballistics section of the Sierra manual and web site is a good source for the above info, as are articles written by Ken Oehler in old issues of Shooting Times as well as some other publications. Additionally, back issues of Precision Shooting will also give you some of the same info. Googling "standard deviation" can also be an eye opener.

Thank you everyone for taking the time to reply.