Spacer kit for MDT long action magazine?

[Cactus kid]

My main rifle is a tikka that lives in an @XLR chassis, inletted for the long action magazine.

Currently I have the 3.56 MDT magazines that run great in the chassis.

I am adding a few barrels to my line up, including a .223 and possible 6arc

Does anyone make a spacer kit to the 3.56 magazine so i can run these shorter calibers a little easier?