Originally Posted by tire_iron

No joy on a drop in fit with the Raptor. Sure - the Raptor does drop right into the upper of the S&W - and cycles smoothly. However the problem begins when you try this with the bolt/bolt carrier installed. Binds up big time.
The hole in the front of the Raptor is a smaller diameter than the stock S&W unit.
The "trough" in the Raptor is just as wide as the "trough" in the stock S&W unit.
There is a small "step" in the Raptor right near the front end where the larger trough transitions to the smaller diameter hole. This is where the problem lies.
There is no step in the trough in the S&W stock charging handle.
Since for me the Raptor is by far the best charging handle - I decided to mod it so it would work. I took a chain saw file and made the front of the Raptor equal the trough, i.e. I removed the step. Then I dremeled it to polish it, put aluminum black on it and PRESTO I have a working Raptor in my S&W M&P10!
Love the Raptor - makes charging the S&W M&P10 so much easier - with either hand.
Hope this helps,
cheers
tire iron