Like gwpercle stated, the heavier bullet is the issue....they are longer. Take the barrel out of the gun and drop a 124 gr bullet in that works and you'll hear it "plunk" and seat completely. Then confirm that it will spin freely in the barrel. Then try the 150 gr and I bet it won't plunk...
The first thing I'd try is a different brand of ammo. You may have some hard primers. If that doesn't fix it, I'd consider cleaning the striker channel. If no luck, contact S&W.
Good luck.
It looks like your twisting your hand to the right on the grip in order to reach the trigger. Make sure your only using the 1st pad of you index finger. Have you tried the small back strap on the 9c (Glocks not adjustable) and do you get the same result? If so, you hand may be too small but I...
Is it possible you didn't have the spring seated properly the first time? Try assembling/disassembling it a few more times and pay close attention to the placement of the spring.
Also, the take-down lever does not hold the spring.
Bruce
JCase, I don't have a CORE so can't comment on the plates/co-witness. I tried to locate the 7.0 MOA MRDS, but they discontinued making them. I even contacted numerous sellers but none left in stock. I went with the 3.5 and it works great, especially for precision shooting. I have this on my...
I bought a Eotech MRDS w/ a 3.0 MOA and I find it too small. Bought a Trijicon RMR02 w/ a 6.5 MOA and it's much better! The 3.0 is fine for precision shooting, but I think the 6.5 is best for both applications (precision/quick acquisition).
MLK18 you may look at Bowie tactical concepts. He does a lot of pistol mods. he can chop grips and do reduction and his work is A-1.
Bowie Tactical Concepts Home Page
Does this happen with every mag? If you're not sure....next time it happens, put a mark on the mag, then change to another and see if it happens again. At least you can rule that out of the equation.