Awesome, That worked perfectly!

Thank You!

I don't know if it's correct or not, but I've been lining up the "bump" on the engine with the circle held in the A strut for aiming, rather than the machineguns aimer.

As a non-native English speaker you guys got me confused. Shouldn't it be "sight" (as in "gun sight" and "bomb sight") instead of "site" (as in "place")?

The Aldis sight consisted of a metal tube 32in long and 2in in diameter. It embodied the principle of the ring sight and the sighting system was in the form of two concentric rings engraved on clear glass screens inside the tube which also contained a number of lenses. When the pilot looked through the tube the image was neither enlarged nor diminished and was always seen with it's centre directly on the axis of the sight regardless of the position of the gunner's eye. The rear end was protected by a rubber sleeve and eyepiece while a problem which had arisen during tests, the fouling of the front lens of the sight by oil or smoke, was solved by fitting a protective disc which could be raised or lowered by the pilot.
The secret of the Aldis lay in its series of internal lenses and the company always insisted that sights should not be tampered with and had to be be returned to the factory in the event of damage or malfunction. According to L.W. Sutherland, writing in
Aces and Kings, the reason for this secrecy was that to prevent fogging of the internal lenses certain gases had at the time of manufacture been introduced between the lenses at varying temperatures and if an Aldis were opened up these gases would disperse. It was claimed that this was the reason the Germans never copied the sight dispite the large numbers captured. The German pilots nevertheless liked the Aldis and frequently fitted it to their machines, the range of optical devices produced by German manufacturers during the war notwithstanding.
The first production Aldis sights were issued to operational units in mid-1916 and by the end of the year they were being delivered in large numbers for use with the fixed Vickers gun or the overwing Lewis by the RFC and the RNAS. The Aldis remained in service with the RAF until the late 1930s and the Americans also adopted it, their particular version being known as the "Unit Sight"*

*The Aldis was a collimating sight, that is, it employed lenses which transmitted parallel rays of light. The magnification was correctly expressed as being 1:1, hence 'unit' or one-to-one magnification.

That's pretty much how I use it, too. I initially did what I suggested to Rob above but didn't like how I was always to the left to aim with the machine gun site... So I got used to guesstimating where to aim and have never looked back.

As a non-native English speaker you guys got me confused. Shouldn't it be "sight" (as in "gun sight" and "bomb sight") instead of "site" (as in "place")?

A Predecessor of WWI reflector gunsights in a way

I've tried mostly shooting at the belly (without doing the "pop up") and have been surprised at how low the gunner can deflect his gun down. I think the difference may be that you are really directly astern, whereas I am more often than not somewhat to the side. More practice is called for - I'd rather not be court-martialed

What is the ring in the center for?