If you are wearing out Charters and Berettas in 1000 rounds, you must be doing something wrong.
The Jennings guns are made of die-cast zinc or zamak-a zinc/aluminum alloy. It's usually OK. for low powered guns. The parts that are stressed are steel.
We clean and lube the gun every week when shooting twice a week. Things break, even as beefy as the Ruger Mark II, I have broke the mainspring housing after about 7000 rounds. I had to buy the part lately and fixed it. I know I can fix the Beretta 950BS, but being so small, I rather buy a new one than to keep fixing it.
I read in the 80s even the Sig P226 cracked the frame in the military qualifying after a few thousands rounds. That's why they chose the Beretta 92F. Things break, it's a lot of stress on the metal firing the rounds.
Most frames are made by milling from a block, not die cast. I have a suspicion is zinc alloy, that's why it's so soft and easily being worn down.
I have no explanation about why the steel of Charter Arm was so bad. I do a little gun smithing, I smoothed out the DA trigger for all my S&W revolvers and my Colt Trouper. I was going to do that on the Charter Arm. When I opened it up, I discovered it was really worn out. It's a SS gun, it almost feels like it used wrong combinations of SS parts that rub each other off. This is a well known problem of SS parts if the metal don't match.
Things starting to break after a few thousand rounds, people that shot 10K+ round do have to change out parts, things do go wrong. I will NOT trust a gun that has over 5000round as something might break any time. For target shooting, it doesn't matter, but if my life depends on it, I'd keep it under 1000 rounds to just breaking in and qualifying the gun.