I'd have to go with atvan on this, you'd be better off with the MD.
In the pull valve, the water has to flow around the edges of the piston. Most improvements to the internal flow before this valve will be ruined at this point, as the water flows around the internal parts of the valve.
As for modding the 310, a
laminator and/or a larger nozzle may be your best option. It won't improve flow, but a more laminar stream will be less likely to break up giving better range (usually!). With a bit of ingenuity you may be able to use the laminator AND keep the nozzle selector, or you may just want to make your own nozzles and selector (although a nozzle selector won't help the flow either!). You may just want to remove the selector altogether (you can always put it back on if you don't add the laminator!).
As for nozzle sizes, optimal size varies between blasters. Its best to slowly increase the size, and stop when you are happy with the range. Try the blaster without the nozzle selector first so you have an idea of what size nozzle the blaster can handle without having an adverse affect on range. If you do go too far, you can make the hole smaller, but it's not as easy.
That said, if you
really want to mod the 310's internals go ahead, but it may be more trouble than it's worth.
