Hammershot 7 round cylinder with spiralised PCAR barrels

Inspired by hitchhiker's work on spiralised Hammershot cylinders:

• https://www.printables.com/@hitchhiker4200
• https://www.printables.com/model/230232-inline-magazine-16-shot-hammershot-cylinder-oh-yes

I found that their cylinders seemed to outperform similar printed cylinders, and I'm almost certain that this is due to the spiralisation removing some surface imperfections in conventional prints, even though fully-spiralised cylinders don't have perfectly round barrels.

So, this design allows us to print spiralised barrels individually and insert them into a normally-printed cylinder (Which do also tend to be sturdier). It could also be interesting to try to create a spiralised holding cylinder.

Easy inserts also allowed for experiments on dimensioning, eventually I settled on approx. 13mm ID with 3x0.3mm lands (The rifling lines). I found that generally speaking less, albeit thicker, lands seemed to eat into FPS less than numerous, but shallower lands, but further testing is likely warranted.

I've included the F3D file to make it easy to customise the inserts.