Starting to pistol smith

The milspec is series 70, it acomplishes its drop saftey feature by using a titanium firing pin. Many people consider the mil spec one of the best values out there. Also many consider it a good platform to custimize. I would recomend you go for the stainless "milspec". It is slightly more but as you experement and mess with parts you don't have to worry about refinishing each time. Another option that is cheap would be a systema. I was waiting on a stainless milspec to send off to be customized and when it arrived I was a little disapointed in this particular pistols quality. I don't think that is indicitive of the overall line though as many people posting on this forum and others are happy with them. Springfield does appear to take some shortcuts recently that is kind of disapointing, but they can be overcome.

For example they use 9mm extractors in all their pistols so they only have to stock one type of extractor.

They seam to have no set part list. It appears that they just have a large part bin and pick parts at randon. I have seen milspecs with a variety of different triggers, one parkerized milspec in my local shop has a stainless barrell bushing(I was there when they unwraped it so it did come that way)

One of there higher end models in my local shop has slim grips with a normal mag well wich is very odd also.

But if you are going to custimize anyway it is a good deal. I haven't heard of any problems with their 2 peice barrels and there frames and slides are forged, I believe so that is always a plus.

If you want to learn as you work, buy one of the Systemas. (When you look it over, you will see that you have a major challenge.) Then, buy a good quality match barrel, a good quality trigger, extractor, long ejector, slide lock, disconnector and recoil system. You should also buy a set of good quality fixed sights.
When you get an aftermarket grip safety fitted and flare out the mag well, it is time to buy some Wilson magazines and head out for the range. When you fire it for the first time, you may realize that you need to replace more parts. Do it!
If you want to be a pistolsmith, you will have to be able to outshoot everyone on the firing line...and that will take some practice. If you can't shoot one, you won't know whether you have done an acceptable job building it.
Accomplish that and you can look at yourself in the morror and say you are a pistolsmith. It might take a decade or more before others will say that about you, but if you apply yourself, it will happen. And, you will have your very own X ring shooter to show others on the range.