It is a good piece. I use it in most of my 1911's.
How would this part have anything to do with bullet velocity? What this part does is allow you to increase locktime slightly, by putting resistance lower on the hammer (towards the pin) as the slide cycles. I think this is why you may be thinking that velocity will be affected. The bullet is already well down the barrel however, before any unlocking occurs - with this FP stop or anyone else's.
How would this part have anything to do with bullet velocity? What this part does is allow you to increase locktime slightly, by putting resistance lower on the hammer (towards the pin) as the slide cycles. I think this is why you may be thinking that velocity will be affected. The bullet is already well down the barrel however, before any unlocking occurs - with this FP stop or anyone else's.