Powder Testing. A Pain in the Brass.

After my recent experience where FFF powder worked so poorly, I figured the old girl was sensitive to powder type, so I set about testing.  I ordered up a variety pack of different brands and granulations.  So far, I've tested about 6 versions other than my standard FF KIK.  I did all the tests with the same 40 grains and the same overall length.  This means some powders had more compression than others.  Obviously, there is a lot more testing to do. 

There are 3 competing requirements in the load.  One is that the initial pressure needs to be strong enough to upset the bullet into the rifling, without upsetting it too much and deforming it out of round or leading the barrel.  Two is that the combustion needs to be regular, steady and clean.  Lastly, the final muzzle velocity needs to be in a range where the bullet is happy aerodynamically. 
There are lots of ways to play around with this.  More powder raises muzzle velocity and the initial upset pressure.  It can make a burn more regular, or more erratic, it just needs testing. 
Coarser powder decreases the initial pressure, and might decrease muzzle velocity, but with my long barrel it may not affect velocity much. 
Balancing off a powder change with an amount change could give me exactly what I need, or just the opposite.

All of these options can have base wad thickness modified to affect compression.  There are at least 100s of possibilities.  On top of all that, a slight change in bullet hardness might alter the results concerning the initial pressure.

So, a pretty picture:

Results:

All tests were at 200 yards, bench rest, 320 grain 30:1 bullet, .060 wad, 40 grains measured, very light compression that varied by load to meet the same OAL.
For the data below I'll give maximum group size and then "9 shot" group size.  A big difference between the 2 indicates a "flier".  I'm not much into calling fliers, as they are still a miss, but the existence or lack of them can point at combustion problems, or bullet quality control issues.
In none of these did I run a chronograph, so we'll need to hold that for a later day.

Powder                         10 shot group    9 shot group.
KIK FF                         9.3                     6.6
KIK F                           8.5                     6.9
Swiss  1.5F                   8.8                     6.8
Olde Eynsford 1.5F      7.2                     6.9
Olde Eynsford  FF        5.2                     4.8
Goex F                          10.1                   8.9
Goex FF                        6.6                     5.6

I should comment that the first load, the KIK FF is my standard go-to load (or it was until I saw the Olde E result), and usually shoots about 7.5 inch groups.  No excuses, a test is a test, but it shows how variable a single round of testing can be.

That Olde Eynsford FF is looking pretty good right now...

Calipers are set at 5 inches.

In the match today it was rather foggy, so my cross stick shooting was not up to my bench rest results in the sunshine.  I did, however, have a bit of excitement.  Near the end of practice, this ejected:

The shell on the left is for comparison.

The trapdoor is a very difficult gun to inspect.  After trying to push the chunk out with wads, we ended up driving a bullet down from the muzzle.  The spooky thing, nothing came out but the bullet.  It seems the ring of brass formed itself into a crude gas check and went out with the original shot (high and right, by the way).  I've only seen one other case like this in a BPCR, and it left the ring in the chamber.  There were no unusual effects, and the reline job didn't give way, so I'm still happy, if concerned.   A thorough brass inspection is in the works.  Cracked brass can be an indication of headspace issues, which I'm not expecting, but I'll check.  Usually a headspace crack is closer to the base.
Have fun.  Be safe.