[Old Man Dave]

Once you start messing with this jonny wou'll realise how complex it is. Until DB came into my life 3 years ago I regarded my gun as a tool to catch fish. I messed with it a bit but not much. Since then I've done a fair bit of messing. I even built a test gun solely to satisfy the need to know.

I see where you're going with the one step at a time and comparison idea but the trouble is that gun performance is right on the edge. A good example is that spears bend when you reach a certain loading. So, say a 6.5mm diameter, X cm long, spear powered by a 16mm band, Y mm long travels at Z speed smoothly through the water. Put a 20mm band on the same set up and the spears ass end tries to overtake the pointy end resulting in non stable travel. Changing any parameter alters the outcome. Trying to analyse the factors is fun but doesn't relate to reality. You need a test tank, high speed camera, loads of spare time and lots of money. Enter stage left the speargun manufacturers. Except the speargun manufacturers have a slightly different agenda to you and me, like ease of manufacture, quantity of sales and profit.

All this aside I love to try to work out what would be the ultimate gun. There again I own an Omer XXV Gold. The 25mm barrel is too thin and light. The spear is way too thin for the length. The band is too strong for the set up. So all round in theory it's crap. Trouble is it shoots miles, with deadly accuracy. Something about an engineer proving a bumble bee can't fly.

Dave