Hi all, just wanted to share in case anyone is looking for this.
the T-Pro model comes with a different bolt release and seems like it’s hard to find. Well, I saw a picture of it on X-ray parts listed as bolt release for the M2 but it’s actually the same one as in the M4. I installed it and it’s perfect.
https://xrayparts.it/en/benelli-spare-parts/4365-bolt-release-button-for-benelli-m2-benelli.html
to clear up any confusion, these M4 stocks WILL fit an M1 by removing the metal sling keeper in the stock. pictured is one of two M1s ive put these stocks on over the years