>>64169854
Anon, I have a Stern Defense upper in 45acp on a FN-15 lower.
I had the "bolt wont cycle forward" issue also but with a Hoffman SS.
I modded 'removed metal' as picrel, per the red lines and 3/16 inch deep towards bolt centerline.
Your pic appears to have the weight removed...
If you use the weight 'see arrow in my pic' the weight will need to have material removed also.
I modded mine with a 1/8" carbide ball cutter and a 1/4" cone stone in my Dermel..
After the mod, it's functions like butta... smoother than a fresh bikini waxed.... well, you know.