Sorry if I was not clear enough on the other thread. I assume too much.
Williams makes the sight for Beeman and puts the Beeman name on it for them. Tony I think correctly identifies the Williams model # that matches the "Beeman Sports Aperture" as Beeman calls it. The mount you saw of mine on the thread the other day if you look close is a Beeman Base (the part that goes on the rail) as you see the name printed on the base Beeman. I then used a Williams Top piece (the part that has the windage adjustment that you can see when looking at the side of the gun in another pic the word Williams at the bottom of the elevation arm (where the elevation markings are and set screw to hold fast the elevation). The reason I mixed and matched 2 sights is that the Beeman would not adjust far enough to the left, and the much older Williams I had has a larger longer windage adjustment screw that lets me get sighted in correctly. All the time I have been using the Beeman/Williams with the stock front sight on the RWS 350M with no problem. Front inserts with the circle would be better for me, but to each his own. (I prefer the aperture front sights vs. post when using peeps and diopters)
The reason I don't offer guarantees and such in this game is that there are many guns that are the exception vs. the norm. As you see in my 350 the Beeman would not work, but that does not mean that the Beeman Sports Aperture is not fine for 90% of the RWS 350M out there. Who can say for sure? I had the Beeman sports aperture model on another 350M in 0.177 of mine before that would not adjust low enough as that gun did not have enough droop as well as a RWS 36 that also did not have enough droop so I had to use an Anschutz sight I had on hand. See photo here:
I USED and Anschutz because I HAD it. If I had an extra Williams LOW riding mount (Williams makes 2 mounts similar - one is higher than the one they re badge for Beeman and another that sits and adjusts lower to the rail I would have to look up the part #'s) that will work on guns with less droop.
If you have a gun that does not have much droop or one you have "fixed" to remove droop you might have difficulties in using some diopters. See what Tim at mac1 has on his site regarding this: Quote per Tim,
"When upgrading, Europeans are used to putting a decent target type peep sight on, rather than an expensive scope. Without "droop", most Target type Peep-sites are too high, and couldn't work unless a correspondingly high front sight is mounted as well! The incorporation of "barrel droop" solves these problems neatly."
I do not give direct recommendations on forums because of all the unknown variables. If I say buy or do: x y or z then there is a problem for someone that has a gun with some unknown issue or variable out of my control and or knowledge I would get slammed for it later on the forum and all I am trying to do is help. I usually say I have done or tried this for that etc. Each has to make his own mind up and be willing for some setbacks in this hobby as part of the learning curve. Good luck all and I hope I've helped some.
Kevin