If you were machining a crown would you want it square?

[hmangphilly]

Silly question really but I have been machining barrels this week - first time but think I am on top of now.

Anyway the question was raised in my mind about what would happen if the crown was out of square, well if you can imagine the moment the pellet tail leaves the crown IF the pellet tail is square and the crown is not then air would leave the space created first so throwing the pellet off and creating a flyer, that's the theory...

So following that theory through then surely every pellet would "fly" off in the same direction so if it was small you would never notice this as it would be dialled out when you set up the scope, it would be a constant.

But my experience of flyers is they can be in any direction and of differing amplitudes so not a constant?

Set me thinking what if the crown is square but the edge of the tail of the pellet is not square, would this be the same result as an angled crown, i.e. the air would be released from the gap created so creating a flyer but in random directions and amplitude.

I tried measuring some pellet tails for squareness (got bored after about 20) against some precisely ground parallel blocks and visualising with my USB macro/micro scope, couldn't see anything but then how often does a flyer happen?

Just some rambling thoughts I had today, anyway on the barrel machining I am getting some super looking in's and out's by avoiding any rotary machining, I am using an engraver with some modified abrasive rubber bits to machine/polish with a reciprocating action instead

Interesting stuff Lol Moore .

How were you checking the squareness of the skirt ? Between 2 ground blocks on a surface plate and eyeball the air gap from the head ? maybe ? ...interested in that . I bet there is some tolerance there .

got any pics of your ins and outs using the rubber stuff ? ( kinda cratex ?) how are the leading edges ?

here's a thought .....wonder what a deliberately wonky crown would shoot like .......wouldn't be hard to find out ......would need to recrown back to square again to check though


Sure the theory about crowns is that it needs to be square or the gas escaping first from the early gap will offset somehow the projectile .

Here's another thought , The lands apply some pressure /contact to the pellet .

If the end is un square , first affected will be the head , do you think the whole pellet could cant in the bore , even before the skirt gets to end ? .Then when the skirt gets there , the same uneven bias is applied and you have a wobbly projectile from the get go .

the tighter the choke , the greater will be the affect .......

does that make sense ???