There is not much market in Law Enforcement or Protective Services for 38 SPL revolvers these days. That is probably why the production is low. S&W has gone almost exclusively to 357 MGN in 38 CAL revolvers, at least for the steel ones. Check out the new M66-8 with the 4.2 inch barrel, if you don't need a new 38 SPL only, for some reason. They will handle the 38 SPL just fine, and S&W actually refers to their 357 MGN revolvers as 357MGN/38 SPL plus P. It saves having two 38 CAL revolver lines. The M66-8 was made a little longer to be legal in Canada, same as Ruger has done with some of theirs, for example, the SP101 4.2 inch model. The new M66 revolvers are only slightly heavier than the M67, probably due to the longer barrel. It is a true K frame, but the barrel is different. It is a two piece barrel, which means that they no longer need to make a flat on the bottom of the rear of the barrel to provide for clearance for the cylinder boss. With the L frame, they solved the "flat spot" problem by making a larger cylinder, thus a heavier weight.
I just bought a new M686 SSR with a 4 inch barrel and highly recommend that model, if you can tolerate a few more ounces and about $150 increase price. I have bought several revolvers on the internet (gun broker) without a problem, just the hassle of going through an FFL dealer. Not too bad. If there is a problem with the gun, S&W will make it good.
Best,
Rick