Boolit size in 44 mag

[SurlyPatriot]

Did some boolit size comparisons using two Super Blackhawk 44 mags.
The 5.5” has .432 cylinder throats; the 7.5” wasn’t measured.

I’m intrigued by the difference in the data sets. For the 5.5” there’s a big change in Stdev and CV with the .432 size, but no change in velocity. With the 7.5”, there’s a bump in velocity with .431 boolits that’s conserved with the.432’s, but no appreciable difference in Stdev or CV.

Boolits are from an Arsenal mould (432-264 SWC - H&G 503 Clone) using range scrap (drops at .431-.432), sized, powder coated (Eastwood) and sized again. Final weight is 259. No signs of leading. Only chronographed, didn’t shoot for groups (6 shots per load per pistol)

Super Blackhawk 5.5”.
11.0 Unique, Starline brass, Win LPP
Size .430
Avg. 1170 Stdev. 25.5 CV 2.2

Size .431
Avg. 1171 Stdev. 23.1 CV 2.0

Size .432
Avg. 1175 Stdev. 9.7 CV 0.8

Super Blackhawk 7.5”
Size .430
Avg. 1190 Stdev. 14.0 CV 1.2

Size .431
Avg. 1225 Stdev. 11.4 CV 0.9

Size .432
Avg. 1228 Stdev. 12.2 CV 1.0

Cool dataset which I will be expanding!

[megasupermagnum]

Interesting, but it looks to me like there is no difference in size, just shot to shot variation. You would have to do 30 shot strings to get any real data from such small changes.

[hades]

What's CV stand for? First time I've seen that acronym.

[SurlyPatriot]

What's CV stand for? First time I've seen that acronym.

Coefficient of variance. Equal to stdev divided by mean.

[243winxb]

"didn’t shoot for groups. "

What a waste of components.:veryconfu

[SurlyPatriot]

Thanks for your insightful feedback.

[hades]

Thanks.

It's been awhile since I've had statistics and I've always just dealt with the mean, ES, and SD.


That is a little weird that the 5.5" showed such a difference in boolit size and the 7.5" didn't. But I would agree with Mega that the sample size is pretty small to really make any meaningful conclusions.


Welcome to the Cast Boolits forum by the way!

[Bazoo]

Consider adding a group size to the dataset, otherwise it might end up being useless. No offense meant, but the fact is, group size is the standard by which the rest of the dataset is quantified.

I digress, that is pretty cool info, thanks for sharing it with us.

Oh, and howdy and welcome.

[SurlyPatriot]

312928312929

Here’s a dataset from a flow cytometer, with 10 micron polystyrene particles analyzed with laser illumination of the particles and collection of 20 degrees of refracted 488 nm laser light. Events displayed over time allowed for approximate gating of 6, 15, 30, and 100 events, chosen at random within the total population of 2544 events.

CV of the total population was 1.02.

Even with a sample size of approximately 30 getting closer to the whole population CV of 1.02, individual samples within the 30 group ranged from 0.76 to 1.15.

So while 30 shots per group would possibly have better represented the “true” CV, there’s no guarantee, and it could have returned a very similar value to the 6 shot groups.

[SurlyPatriot]

Thank you for the welcome!

[DougGuy]

I find it odd that you include throat measurements for the 5 1/2" but neglect to measure the throats on the 7 1/2" and proceed to make very detailed comparisons. To me that could be a significant variable to consider. What did you measure throats with?

[SurlyPatriot]

The 7.5” Super Blackhawk is a friend’s. He came along for the shoot, so we included it in the chronographing.
I have several pin gauges between .429 and .434 — nothing over .432 fits in my Ruger’s cylinder throats (and they’re all the same size).

[44MAG#1]

I have a few questions to ask.
What does all the testing with the different bullet diameters for?
So, the larger gives a little more velocity. What does that mean?
All the SD's are very good regardless of the size to diameter.
The velocities are good.
What else could you want?

[reloader28]

"didn’t shoot for groups. "

What a waste of components.:veryconfu

I agree 100%
I have never understood why someone would care more about numbers than how a load groups.
Maybe its just this part of the country but its extremely rare to get the tightest groups AND the tightest numbers together. Internet myth I think