Can I assume that I can fire 125 gr. bullets through it? Will it flame cut like I was warned on my Model 19?
Suppose to pick it up today, has S&W followed Springfield and done away with the internal lock?
The problem is not flame cutting on the Model 19, it is cracking of the forcing cone with a steady diet of full powder loads. The crack appears at the bottom of the forcing cone where the barrel has been relieved to make clearance for the cylinder crane.
While it may happen more quickly with light weight bullets such as the 125 grain bullets, it can happen with a steady diet of full power 158 grain bullets.
My Model 19-4 had its barrel replaced for a cracked forcing cone after I fired lots of 158 grain full power loads.
The current Model 66 has been re-engineered a little to strengthen the forcing cone.
The L frames were originally designed in part to strengthen the forcing cone area to be able to handle a steady diet of full power loads.
The grip frames on the L frames are the same size as the K frames.
Except for a few J frame revolvers where "no-lock" versions are offered for some specific markets, I believe S&W still installs the lock in their revolvers. At as as of 4th quarter, 2015, the S&W revolvers still came with the locks.
The Models 586 and 686 are great revolvers.