Slight unburnt powder on 9 major load development

[balmo]

I did some load development for a 9 major on my CK Arms Thunder w/ 3 popple holes. I have PD 124gr JHP, Win SRP, sitting at roughly 1.148" COL, with the following loads of Win Autocomp (5 samples each):

6.8 grains: mean-1413, std dev-16.7

7.0 grains; mean-1452, std dev-10.9

7.2 grains; mean-1449, std dev-10.3

I did not realize until later when I cleaned my gun that there was some unburnt powder accumalated inside. I did not notice unbrunt powder spewing out when I was shooting though. I did not observe my gun enough whether it is the lighter charge that caused the unburnt powder or the heavier one. What do you guys think?

Also what does it means the the 7.0 and 7.2 grains are virtually the same in velocity, granted 7.2 has a little better std dev? Thank you.

[jcc7x7]

I "think" it means you're at the point of diminishing returns.

Which means you're at max the load is going to work at.

Not an expert just following that thought process for the last 40 years or so on reloading high pressure cartridges

[ChuckS]

Why are you loading so hot? Your 6.8 is 175,2 PF! If you are trying to get the gun to shoot flatter, you may want to try a slower powder (HS-6 for example).

Just a comment: when trying to figure stuff out, 5 round samples may not be enough, especially if you are using mixed headstamp brass.

Later,

Chuck

Edited August 3, 2016 by ChuckS

[Miranda]

... there is the matter of deciding --> "do you want to know"

you tried three different loadings

unless you run each group and then clean or inspect before moving to the next group,

you will not be certain which produced the un-burnt powder.

I am thinking the last group is the residue creator

I also agree with jcc7x7...

miranda

[Powder Finger]

in general more powder not much change = danger.

[Hi-Power Jack]

(5 samples each)

what does it means the the 7.0 and 7.2 grains are virtually the same in ?

It might mean your sample size is too small ...

I usually send 20 rounds across the chrono before I decide what the velocity is ...

[Miranda]

ah why am I laughing,

we do not often walk lightly on the subjects here on this forum.

and yet I see that we are walking lightly.

I have only read about the meanings of loading and the results

and we are looking at a classic example of how most powders display

the end of good results.

so I can't state I know there is no reason to push past.

the advice I read was you will get no real improvement in bullet speed

and you will only increase your chances of destroying gun if you keep adding powder.

cauldron boil and cauldron bubble...

miranda

[BeerBaron]

yes, generally when more powder doesn't equal great velocity that means you are at a point of overpressure. it's causing incomplete burn of the powder too.

as the other guys said I'm also not sure you need to push those projies so hard. 1380 FPS is a general kind of number to aim for for major PF. your lowest load is way over that.