Point. The Primal Demon door does lock behind you, I believe. But Bargate is kinda boring if you go back, at least if you already emptied it of everything. There's nobody there and nothing.
a quick way for me would be start a new game and play up until u have to do the quest where you have to save the grandson from the hobbe cave. now after you get there befor u enter the the quest save right be for you go in to the arc that takes u to the grandma's house. After you save go in and go to the small dirt patch up buy her house dig up the key. After u dig up the key save on the file u saved before u entered the arc. then load the file u saved before u entered the arc. this way u can keep on getting and getting keys until u have enough for the armor.
a quick way for me would be start a new game and play up until u have to do the quest where you have to save the grandson from the hobbe cave. now after you get there befor u enter the the quest save right be for you go in to the arc that takes u to the grandma's house. After you save go in and go to the small dirt patch up buy her house dig up the key. After u dig up the key save on the file u saved before u entered the arc. then load the file u saved before u entered the arc. this way u can keep on getting and getting keys until u have enough for the armor.
If you're talking about the hero save glitch, that can seriously mess up your system