Don't know when you sent it back, but for the last two years, Benelli Defense has displayed a M4 with the SureFire fore grip at SHOT show. The SureFire rep tells me everytime I ask that 100% of production is going to Benelli Defense.
I told him to look at this website to see how popular the foregrip actually is.
I'll see him again in 95 days, it'll be interesting to see what he says (Benelli going with an in-house fore grip may mean the real end of the SureFire M80)
The attached photo was taken in January 2019.