Hope to try out my new Chronograph Part II

[tbooker]

Well I got out to try out some new loads and my new chronograph. The good new is I didn't shoot the chronograph but now that I have my targets and data from the chronograph what do I do with it. Here are my targets with the print out from the chrono. I did 6 strings of 5 shots each out of my Savage 25 .223. All of them were done with 40gr V-Max using BL-C2 with 27.5, 28, 28.5, 29, 29.5 and 30gr powder. I was just learning how the equipment worked and on the last string I forgot to press the new string button so target 6 shows the data for target 5 & 6. Data was collected using Shooting Chrony Gamma Master at about 10' from the barrel. Any who here are the targets.

Srting 1

String 2

String 3

String 4

String 5

String 6

 

[sniper58]

If it was me, I'd be stopping at load #4 and staying with that one.
Loads # 5 & # 6 appear to be starting to string vertically.

 

[L0veM0nKeY]

Yup, #4

 

[Ron AKA]

You have some nice targets, and it looks promising. What I would do is pick a datum point below the lowest point of impact. Measure every bullet in the vertical direction only to the center of each bullet hole. Ignore any horizontal. For each target average those measurements. Then plot the vertical averages vs the powder load, and also on another graph against the velocity. What you are looking for is flat spots in the graph where velocity goes up (or powder weight), but the average point of impact does not go up. This is a velocity tolerant zone, or sweet spot. In theory velocity is the better measure to use, but I think the reality is that powder weight is a better measure of velocity than the chronograph. I have a Chrony Alpha, and I don't really trust it that much.

Here are a couple of examples of what I am talking about. I was testing three different bullets at 300 meters. At 100 meters it is harder to see the vertical variation, and longer distance is better for evaluating loads. Rightly or wrongly I picked a sweet spot velocity of about 3420 out of this testing for all three bullets.

 

[tbooker]

So what can I take from the velocities.

 

[Ron AKA]

So what can I take from the velocities.

Some load to minimize the ES and SD, and tweak their loads to get the best measured results. However, I'm suspicious of the accuracy of these numbers especially when you only measure 5 shots. What I use velocity for is to identify which velocity my barrel like. My thoughts are that velocity is transferable from one bullet to another. If you barrel likes 3200 for example you may find that same velocity works in different bullet weights and designs.