I've just used my chronograph for the first time and I'm wondering what would be considered good when it comes to speed variations.
Here's my results for the .223
ADI brass, ADI Powder Hornady V Max 55g
This brass has fired it's 3rd shot for this test. It has not been sorted for case volume or weight.
Each powder charge has been weighed out on beam scales.
Assembled with a blody hammer and a lee loader !
3128
3133
3145
3113
3154
3168
3134
3144
That's a 55 fps variation.
I recon sorting my brass into weight or volume will make a big difference for the .223
.243 RESULTS
Winchester brass, ADI powder, Sierra 100g
This brass has fired it's 7th shot for this test.
It HAS been sorted into batches of brass weight.
Trimmed for length and annealed.
Each powder charge has been weighed out on beam scales.
Assembled with a hammer and a lee loader !
2642
2647
2631
2634
That's 16 fps variation. ..I probably should have shot a few more for a broader sample group for the .243 but at least I now know my speed.
I should be able to preserve the barrel somewhat with that low speed.
I'm actually reasonably happy with the results considering all factors and I'm expecting better results with the .223 once my brass is batched.
The .243 is being used to 500 meters and the .223 is being used out to 350 meters thus far.
According to my ballistics calculator, at 350 meters a 55 fps variation will give me a 1" difference in drop for the .223
And the .243 with only 16 fps variation the difference between fastest and slowest will be 1.2" @ 500 m
That's probably better than I can shoot in the field
As a side note before using the chronograph I estimated the speeds based on poi over different distances.
My guesstimations were,
2380 fps for the .243 (340 ish out, but I really hadn't put much effort into working it out)
3150 fps for the .223 ( almost spot on as I'd spent a bit of time plugging the numbers into this one)
How cool are chronographs!