I was wondering for long range shooting out to 1,000 yards what is the largest amount of velocity spread between shots? I have a really accurate load for my 300 but I was going to chronograph it.
+1 On what Montana says.I take chrony readings with a big grain of salt. I bought a chrony alpha this year and shot it back to back with an old prochrony and they varied anywhere from 5-50 fps. I put more stock in the actual verticle spreads on the targets. Chronies can be helpful, but unless you have a really good one (and how would you know if you do?), I figure them for plus or minus 50 fps. I have seen one read exactley the same reading for the first two shots and then 50 fps different on the third.
correct me if Im wrong but velocity spread is represented in vertical climb/drop?
There's a reason that their higher end chronographs are capable of larger shot strings."Since Standard Deviation is the most important information that your chronograph can give you, it is useful to understand the reason for this. At least 10 shots are required to obtain a reliable average and Standard Deviation. Fewer shots (such as 3 or 5) are typically "small samples", and are considered unreliable when measuring anything variable."
Only in a very rough sense..
Drop can be influenced your bullet BC variance.
Your barrel could throw bullets any direction as it comes in and out of tune.
Your load could put the barrel on that edge of tune.
Your system inaccuracy is always there.
Certainly worth shooting still, to see how good your load performs at range.
What you say here is true, but the verticle spread indicates velocity spread more so than horizontal spread for obvious reasons. The bottom line is to strive for the tightest group load as possibe.
I disagree with generalizations about the value of ES, or that a great deal of shooting is needed for statistical value. Long range shooting should not be seen as a game of probabilities. Your not playing odds here.
To focus on your actual capability, rather than probability, you cannot deny ES.
Every shot counts
ES is of as great of value as it is accurate. Accurate ES numbers are very valuble. Inaccurate ES numbers can be counter productive leading to rejecting a good load or selecting a bad load. Most of the chronys used by shooters are of marginal accuracy. If you put them back to back with other chronys, that becomes readily apparant. The fact of the matter is that ES and SD are statisical observations which means we are in fact talking about probability. No way of getting around that period. And... the greater your statistical population the better your observations and conclusions will be IF your data is accurate. When we talk group size on a target, we're talking statistics and probability. When we are in the field on a windy day deciding whether or not to take a shot, we are weighing probability, period.
Actually my statistical reference was about standard deviation. It doesn't matter if you are speaking of bad apples to good apples in a crate or velocity variations in your pet load, the calculation is a statistical calculation and more data points equals more robust output data. The people at Shooting Chrony recommend a minimum of 10 data points.
From the Shooting Chrony Manual:
There's a reason that their higher end chronographs are capable of larger shot strings.
ES is different. My suggestion was that if you want to use ES then use it, however, how the gun shoots is a much better indicator than ES imho. Not saying it's not useful. But ES is an indicator of the variability of the load more than anything (not saying it's the only indicator but it's the primary indicator imho). How consistent is the powder burning in your rifle / barrel combination? How consistent is the batch of primers that you used? How well did you measure the powder? How consistently did you seat the bullet? How consistent is the neck tension? How consistent does the barrel remain as you foul it with more and more rounds? I imagine that I'm leaving a lot out.
I don't see Long Range shooting as a game of probabilities. However there is a probability of success given a set of conditions. That's one of the reasons we reload and people build custom rifles and custom barrels. Decreasing statistical variability increases the odds of hitting where you aim.
Anyway... I'm not going to beat this to death. I don't spend a lot of time looking at chrony data because it takes too much time to do it right (for me). I shoot paper and when things get right I get the satisfaction of seeing the results and I get the pleasure of watching the load come together.