Too thick for standard buffer - Spikes Tactical 9mm Buffer Spacer

I'm using a standard AR buffer tube (inside length measured from back of buffer tube to retaining pin 7 1/16"), standard AR buffer and carbine spring and spacer will not allow the bolt to retract enough to engage bolt catch. Tried this spacer in two other ARs and same thing.
Thought I could use the spacer instead of a stack of quarters in my AR9 build but just too thick. Be nice if Spikes could make a lightweight aluminum adjustable spacer.