I have a Aimpoint with a ARMS 22M68 and cantilever spacer with an ARMS 40 as my back up on my Bushy.  I would like the Aimpoint lower, whereas the co-witness is through the middle of the Aimpoint as opposed to the bottom third.

I understand I could just buy a half spacer for my ARMS 22M68.

My question is, if I buy a ARMS #38 swan sleeve, can I run my Aimpoint with ARMS 22M68 without a spacer to get the centered co-witness effect?

Thanks for your help in advance.
Greg

One of my guns is set up as you describe.  It is not centered, but seems a little higher than 1/3rd of the way up.