According to Wikipedia, the SNS term originated in a newspaper story published in 1917 to describe a cheap pistol. It became more popular in the late 1960s. Later immortalized by Lynyrd Skynyrd.
While not as fancy or costly as a S&W or Colt, The Iver Johnson revolvers were several steps above the SNS guns. Many of the old top breaks were neglected, and in poor condition (Mostly from improper cleaning!) and were sold off for cheap. Some people just didn't understand that many of today's safety features were invented on top break revolvers by Iver Johnson and H&R.
The standard bullet weight for 38 S&W is a 146 grain LRN bullet. However It is easier to find 146 gr. wadcutters. These will work fine if you load them with the bullet sticking out of the case to the recommended overall length. When The original Hydra-shok bullet came out, it was sold as a loading component: a 146 gr full wadcutter containing the huge hollow point with the post in it. I never loaded any in 38 Special, I loaded up 25 in 38 S&W, and that was my pocket gun carry ammo for several years! Never used any on people! But an angry dog or 4 found out that 38 S&W is a real gun, I only had top breaks and kept the loads to Lyman #45 specs. Any solid frame revolver could withstand a little beefier load.
Last summer I loaded up a batch of 350 38 S&W's for my brother and I I couldn't find any 146's, so I used 158 RN and SWC bullets. Lyman #45 and some later issues have data for them too. Stick with pure lead or a very soft alloy. .357" bullets work fine in my ,361 guns.
For loading dies: DO NOT USE 38/357 DIES! you will under size and ruin your brass. I had a batch of "New Handloads" from a commercial loaded that were sized on Special dies. Every fired case split just above the web from this mistreatment!
A 38 Super die works fine for a sizer die, 9mm Lugar flair, seating and taper crimp die worked fine. (I have a Lyman 310 tong tool die set, but prefer loading these with 7/8-14 dies.) I like WW231 for powder but Unique and Bullseye have always worked well! Standard Small Pistol Primer only, The brass is very common in nickel or plain brass. Several years ago, South Africa surplused out literally tons of 38 S&W brass with a blank head stamp. These were intended as starter rounds for small mortars from the WWII era. There is no difference from regular pistol brass, but at the time my best friend and I got them really cheap! BTW, 38 S&W has a larger rim diameter than 38 Special and uses a different shell holder.
Buy, borrow, or piece together a loading die set and assemble some ammo and enjoy these affordable and wonderful little guns! I don't have a Terrier (yet) but my Regulation Police, Webley, BSR's and top breaks all shoot very well with this ammo!
Enjoy!
Ivan