Disasterous PP results!

[303Guy]

I loaded up a batch for my No4 and tried them today.



I would have liked to have take a photo of the group but I coudn't get it into the picture!

However, after resighting the rifle under zero wind and zero fore-end stress and getting what appears to be sub-MOA with j-words, those PP's hit point of aim at closer range. Made me wonder whether the patch was staying on for some distance? There was no 'confetti'. At least one boolit got pushed back onto the powder. I know this because I ejected the unfired round and left the boolit behind! (And spilled the powder because I did not use a filler as the case was full).

So, back to the drawing board! (It was worth a try!)

[leftiye]

Sounds like the RMP effect had somewhat to work with in this case. Keep at it, it is supposed to work (for 150 years now)!

[303Guy]

The RPM effect! You mean the boolit is distorting in flight due to RPM? Mmmm.... Lead will 'flow' under pressure. Mmmm.... Harder alloy next time then? I was driving these to "normal" velocity, maybe around 2300-2400fps. I was about to give up on the particular approach I used. That being the tough paper (I think it is 100% Vellum tracing paper) and a short base overhanging skirt filled with waxy-lube to form a 'wax wad'. These were boolits patched with my 'paper sleave' experiment.



The sleave gets soaked in water untill the casting will fit inside. This only works with this tough tracing paper.

[leftiye]

I've come to think that it isn't really about tough paper (tensile and tear resistant) as much as getting a solid layer of compressed "pulp" between the boolit and the bore maybe? What I meant previously wasn't that the boolit distorted in flight due to rpms, but that it seemed to have plenty of distortion for imbalance and rpms to use to cause inaccuracy. Larry and I seem nowadays to agree pretty much as to what is going on, though I really think that the unstable presentation to the airstream is a much more potent deflection factor.

[303Guy]

OK, so flight path disruption would result in an exponential opening of the group with distance. This is the second time I have noticed this effect but have not fired enough controlled shots to form any conclusions. Thing is, I have only done paper separation testing at muzzle distance and then mostly with light charges. The tough paper doesn't form 'confetti'.

Oh, the castings I am using are not exactly perfect. That could be playing a part too. The other thing is this is with my two groove which does cut into the lands.


This is a 'light charge' patch.

Here one can see the cutting into the land.

This was a full tilt load but not max.

This one held the rifling well with tracing paper. Trouble is, I don't remember what charge I gave it, but it was not too light, going by the patch remnants.

It was this result that decided me to pursue this boolit patched with tough tracing paper.

Hotter loads do shread the paper better. The load I tried out this past weekend was positively hot! (Meaning full tilt).