TargetTalk

Good to know. I am similar situation. I also got a letter from MEC to say they work fine on spring loaded sights like Pro57.
If you have more than one rifle you can buy just the adapter part that screws into the rearsight.

Just borrowed one of these off fellow shooter (he didnt like it at all, caused him to overload [multi bull targets]) as am left eye dominant & thought it might be worth a try to gain a bit more clarity with aging eyes. With only quick set up it seems to work pretty well, but needs much more testing. Initial thoughts, would be terrible for outdoor as it restricts your field of view so you wouldn't be able to see wind flags. Yes it does seem to- make/help you center your eye behind the sight, but the view I get through the Swap is not flash. It acts as a peep so cuts down field of view. Your adjustable peep still allows you to adjust light, but size of rear peep view stays the same. Might see if I can take a picture that might show what I see. Also seems to be light bouncing around inside and so you see parts of the inside, and its not evenly round. Sorry for poor description, and I may need to take more time setting it up. Would like to hear from others who have used one for a descent length of time.

Looking at the photo that looks like a similar device but not a MEC or maybe an early version? Different shape.

TenMetrePeter wrote:Looking at the photo that looks like a similar device but not a MEC or maybe an early version? Different shape.

It's not a Gehmann I think; that attaches to the eyepiece. The device pictured above sits between the rearsight and the eyepiece. The attachment at the rearsight looks like a Centra. The body is more rounded at the corners, perhaps the website photos are pre-production.

It has MEC on the end of it.

I finally got one. Plus a spare mount for my other 6 yard sight. I had to re-zero the sights after moving the rearsight forwards about an inch to maintain eye relief. Had some practice shots - it was not as awkward as I had feared, easy to keep the image in line with my better eye and I can make out the aiming mark clearly now! There is a universal joint adjustment with torx screws for getting the foresight centred in the rear and for eye height. There are some stray reflections but these are from inside the mount which is blued but not matt - easy to paint with some camera paint I guess.