I have a definitive source: Noah Webster 1892.
Reticle n. (Latin reticulum, from rete, a net) a small net.
Reticule n. a little bag of network; a lady's work-bag, or a little bag to be carried in the hand. 2. In a telescope, a net-work dividing the field of view into a series of small squares.
Somewhere along the way, someone thought it simpler to reduce "reticule" to just a handbag. While optics existed before 1892, obviously a standard consensus was not realized because of the extreme rarity of them. I have always used reticle, but acknowledge reticule is also correct. I would also acknowledge crosshair or specific naming of the reticle like "German #4", "Horus **", "duplex" etc. when ended with reticle/reticule. Technically the old definitions are not 100% correct either, for the field of view is not a square, subsequently cannot be divided into anything but wedges; and scopes have nothing to do with nets. So I'll prefer a later consensus for "reticle". But if you refer to your car tires as tyres, that is still a standard but they are not the wheels, nor are wheels the rims.
Units for measuring mass are nouns, and to weigh something in a unit is an intransitive verb, hence it is incorrect to say "how many grains is the bullet." It is "how many grains/grams does the bullet weigh?" I often fail, as will most but at least strive to write and speak properly... especially in your native tongue. Have some objective pride in doing things well... half baked efforts and half baked results are gross: just look at the government and electorate of Canazuela.
seems to be the normal 
these day's
