As thxmrgarand said, they are very well made SA revolvers that George contracted with J. P. Sauer in Germany, and were also noted for having a longer grip than other SA's to fit man-sized hands. While I had a 357 MAG Herter's for a short time in the mid 60's, I soon upgraded to his 401 Power Mag and had it until only a few years ago when I let a collector finally talk me out of it. I killed a lot of big game with it in the 60's and 70's - it made a perfect hog gun. It was a favored silhouette revolver for me after that. Over 35 years of good service out of it, and I sold it for 7-8 times what I paid for it. Still have the old Herter's dies for it, and with the original Herter's 401 brass a high priced collectors items now days, soon found I could just reform 41 MAG brass to shoot in it. Still have a few of the original cast bullet cartridges that Herter's sold for it, and they are hot loads. So they are very strong revolvers and were almost a give away in the 60's, as was most of the Herter's offerings back then. I wouldn't be concerned about shooting anything except maybe the hottest loads in it, and it probably would even handle them without problem. GCA '68 was their demise when George couldn't ship them direct to his customers anymore, and he begrudgingly removed them from his catalog.
Having grown up on a ranch, I ordered almost everything out of his catalogs from a young age (and from L.L. Bean, Carhartt, Orvis, etc catalogs). All of Herter's offerings were very serviceable, and low cost compared to other places. George was quite a character with salesmanship akin to a used car salesman in a plaid suit with a polka dot bow tie and saddle oxfords. Really got a kick out of his wild-eyed claims. The books he wrote are comical too although very informative, and his new catalogs each year were eagerly awaited. Still have a couple of mine from the late 60's-early 70's. I must have worn the earlier ones completely out as it was a great way to pass the hours and dream of better things with his catalog in hand. He offered it all for almost any sport and it was all unconditionally guaranteed. He boasted the highest quality and workmanship at the lowest prices, his guarantee was a full refund if you were not fully satisfied and he stood behind it. I won't say without question, as George really wanted and trusted the input form his customers. Remember talking to him on the phone many times. Not to complain, but to ask questions or get his opinion on something.
The company was not the same after George died. I'm not sure if it even stayed in the family, but George must have turned over in his grave for what it became. Literally a pale shadow of what he had made it.