Powder position sensitivity

I acquired a lab radar and was learning to use it. My velocities were pretty erratic so I started to do some powder position experiments. First by pointing the muzzle down so powder would be forward in the case, then by pointing the muzzle up so powder is against the primer. All shots were done with the gun horizontal after positioning the powder. 10 shot strings were collected. Load is well within 10 ring accuracy at 50 feet.
Load
3.7 gr Alliant E3 (yes, I know, not a common bullseye powder)
167 gr NOE cast, hi tek coated
Fed brass
Winprimers

Powder at bullet: velocity =793 fps, ES = 98, STDEV=33, hi/lo=838/740

Powder at primer: velocity = 847 fps, ES = 56, STDEV=17, hi/lo=863/807

I know, neither shows great statistics, but the difference is pretty striking.

More to come with traditional bullseye powders...

was there a discernible change in group position on target?

I didnt notice as I was not focusing on target but trying to keep gun in correct position for radar to see bullet... another thing to try...

So who is gonna start making custom 45acp wads lol.

You could do what the black powder boys do, fill the case the rest of the way up with cream of wheat! LOL

… Alliant E3 is one of the least dense powders. It is even less dense than Clays. 
3.7 gr of E3 uses a good amount of the case volume, which helps reduce powder position velocity variables. Put another way. By volume, it would take 5.17 gr of BE to fill the case as much as 3.7 gr of E3.

I used to use a little toilet paper for some really light charges.
Stan

I would be interested to correlate this research with process of making shot, - raise gun, start lowering it, ........
BTW, when I test my reloads in RR, I always first rise muzzle of the handgun to almost vertical position, and then lowering it. I do same for each shot.

AP

I first started researching this when shooting NRA AP on a moving target. Our first shot is always from the holster. I found that I would have X number of bad, not called shots to left and right of target. I found that depending on the cartridge, the load etc, those first shots were 75 -150 fps slower than the average of the non-draw shots. 

I then changed to a bulkier powder, and seated bullets just a little deeper. This reduced the delta between the first, holster shot, and the remaining shots. The delta did not seem to matter too much on static targets, but it revealed itself on a moving target.

I also belief that the long line and a ransom rest reveal the better groups, because typically the gun is elevated before each shot, and lowered in the same manner for each shot. This causes the powder to be more consistently positioned in the case, especially, if it is a lighter load. Further, I believe some of the hotter loads tend to be more accurate, because with a greater volume of the case being taken up with powder, then powder position variance is also reduced. 

Some of the bulkier (less dense powders) are E3, Clays, Red Dot, VV N310 and WST. The volume of these powders with light charge weights, may explain why they are good choices on the lighter loads. All very interesting.

Velocity difference confirmed... not confident in group position as it was weird raising gun that high... target showed it...