@ Zarlog: Nope FCO is all clear tempered glass now, but when it first came out in the 70s and early 80s there were frosted/serrated FCO glasses. My OV-15TD FCO has a serrated glass lens. I like it much better since it cuts back on the glare from the lamp, especially when a clear lamp is used. The reason why all metal halide products are only available in glass is because the scorching hot shards of glass will melt into the plastic lens during a lamp rupture. Even with glass refractors the bits can really stick to the refractor.
Horizontal PSMH lamp explosions are particularly violent since the arc is less stable in MH lamps when run sideways. MH and MV lamps run better vertically. With the old medium pressure MV lamps, a vertical lamp was a must. For GE's Form 109, an ingenious device was installed above the reflector to stabilize the arctube, since the Form 109 has a horizontal lamp. The modern day high-pressure MV lamps that came out sometime in the 50s could run in any position. With MH, the lamps are not as bright when run sideways as they are when run vertically.
@ Ryan: LOL Yeah it's hard to come up with totally unique designs that don't look really oddball lol. The R250's door does look like a M-250R2s but the top housing is a little boxier like an ITT 13 The R250 was designed basically as an elongated R150 with a larger refractor (standard small cobra lens as opposed to the OV-10 glass on the R150) and longer housing to fit a 4-bolt fitter and larger ballasts.
When I initially drew the R400 it came out basically being a drawing of a Model 25 to a "T". If you look very closely you'll see the erased line of the door, where it curved upward just like a Model 25 door does. It uses a Model 25 glass too so it really was a clone lol. So to make it different I indeed modeled the door after the OVM. So my inspiration for that light was a cross between the OVM and Model 25 lol.
As for the R1000, it actually uses a classic M-400 glass, so it's technically a medium fixture (basically the 1000W version of the OVX lol). It was actually based off the Powerlite B2255
which looks a cross between an OVM and M-400A. Powerlite made the same fixture casting in 1000W and called it the B2228. The fixtures were the same other than using an inverted socket bracket, which set the socket further back so a large BT56 lamp can fit (a 1000W lamp indeed fits inside a M-400 glass!)