If military procurement was based on the desire for something new, I would be extremely happy.
However having dealt quite a bit with military procurement it's based more on what was purchased in the past. Obsolete patrol slings, aluminium wash basins, melamine plates and cups, tac vests etc.
For new items, sometimes it's based on only seeing one product without seeing other options.
There are few times when a variety of items are tested fairly against each other, however sometimes one item might be excluded due to the wrong sized paper used on the quote (No $hit, this has happened).
Dammit, now I'm starting to rant...........
Darren,
The point being of course, that we just don't update something if the current item meets the defined requirements. The equipment that is purchased is based on the user defined requirements which are captured in the bid. The prioritization of the critiera can sway what type of product is purchased particularly if the solicitation is written poorly.
I have bid on work overseas that turned out to be very lucrative because the contracting officer did not write a good solicitiation. Same goes for firearms. If for example, you use accuracy at 300m as the sole discriminator between the systems as submitted. You could have the best shooting rifle at 300m but equipped with a bushnell scope with alumuium rings. Using a tapco stock and grip. If the solicitation does not articulate the requirement or standard, the manufacture or bidder can use whatever they like. Sometime we get crap gear in DND because the soliticiation was written so badly. That is why it is important to have professional contract guys to support solicitations...