I can kinda see where the OP wants to start with crap guns as a training issue.
Turn a $100 .22 crapfire into an accurate rifle is a lesson learned.
The fact it would not make it a $500 tack driver rifle is understood in his opinion as I understand because its a training gun only.
He needs to learn the basics of making a crap gun into a tack driver to establish a reputation and then move on to that specific caliber/platform to create a reputation among the gun community. Some on this forum have done that.
One of the greatest gun makers in this country is JJ Perodeau that lives/works in Ok.
He had to do years of apprenticeship in Belgium before allowed to actually touch a firearm and then he had to apprentice under a master gunmaker.
(notice I did not say gunsmith)
A person can aspire to be a gunsmith with general knowledge of guns,machining and the ability to repair just about anything.
A gun maker is the next level beyond.
I KNOW that I cant take some worn out rusted gun and turn it into a "forever" sidearm.
I also at this point have no background at all, worth mentioning at least.
Just need to start somewhere, however it seems like where to start is a point of contention, which I did not expect.
The gunmaker thing is so far out of my league, I am not even considering something like that.