I'm installing a set of Trijicon HD's on my M&P Shield.  I removed the stock rear sight by drifting the rear sight out from left to right as you are facing the rear of the slide (as if you were shooting it).  I'm a bit confused on whether the new Trijicon HD rear should go on from left to right or right to left.

I was watching an APEX video on YouTube and it shows him installing the rear from left to right.  However, if I push the rear sight into the dovetail by hand as far as it will easily go without too much force, it slides in further if I push it from right to left than it does if I go from left to right like he showed in the video.

Is it alright to go from right to left (opposite what the video shows) because the sight "starts" further in?  Or should I definitely be going from left to right like the video despite which side it starts easiest from?

Thanks!

If the sight starts deeper from right to left, then fit and install it from that direction.

Thank you sir.  Much appreciated