There are interesting discrepancies for all the gunsights. Guns without telescopic or some sort of reflector sight had sights mounted on both the receiver and muzzle (or in a corresponding position on the cowling). The "sight" (sometimes called an "iron sight") is actually made up of both of these references. Either reference by itself is useless and the shooter must line each up to properly aim the gun. Without a reference on both ends of the gun, iron sights are worthless and neither the F.1 or F.2b have both fore and aft references so, if you move your head away from the default forward view position the sights don't work. Looking on line, I've seen pictures in which the Camel has a post on the receiver and ring on the muzzle (both on the left gun) or a tube sight on the centerline but ours just has a center mounted ring. I can't find a good picture of the Bristol but one I found appears to have both a forward ring sight and post hanging down from the rear of the upper wing. The observer's Lewis gun has a good set of iron sights, strange there are none for the Allied pilots.
Both German planes at least appear more accurate because they have iron sights on each gun but the D.VII is the only plane in the set that actually has an in-game usable iron sight (the large one in the center) with front and rear references. This sight and the iron sights on the Lewis gun are the only ones that actually work when you line them up. The iron sights actually on the guns themselves though doesn't work because they don't line up correctly and you'll miss low if you use them (I'm sure this has something to do with the graphics modeling).
Provided you do not move your default forward head position the ring sights (and crossed brace wires on the DR1) on all the planes work fine but you'll lose this as soon as you move your default head position in either up/down or side/side directions. If you use Track IR as I do, the only iron sights that work are the D.VII and F2b's Lewis gun.
So what's this mean? If you use the normal AH view system, don't move your default forward view side/side or up/down if you want an accurate sight (you can move it closer or further back). If you use TIR then it gets more complicated and you have to force the forward view. You can do this by pausing TIR or do what I do. I have an X52 with a two stage trigger. The first stage is set to select forward view (keypad 8) which forces the view to line up with the aircraft axis, the second stage fires the guns. You can then line up the iron sights on the D.VII and Lewis gun but it won't work with the other sights. The only way to make this work well with the other airplanes is to put a reference dot in the center of your monitor and that becomes your sight. You can also use the dot if you really need to change your default forward view head position in the normal AH view system. Of course, you can't beat filling your windscreen with an enemy aircraft before pulling the trigger, that way you can't miss. This may be one of the reasons there seem to be so many collisions in the WWI arenas (well, that plus all the wings blocking your views).
