The US Army Field Manual 23-10 contains a lot of good information which can be helpful for the new long range shooter. While it is based upon the Remington 700 bolt action rifle and is intended for basic sniper training, there is enough in it to make it suitable for learning to shoot at long range using any modern day bolt action rifle. However, wading through its many pages and trying to separate the information into what's needed at what point in the shooter's development can be a bit overwhelming. It's also tempting to move too fast through the learning curve if you rely solely on that publication.
I'd recommend working with a book or instructor with a focus on mastering basic shooting skills. Then, perhaps, looking through 23-10 (it is interesting) and gradually building on those most basic elements.
I do believe it is possible to become an expert "self taught" long range marksman. The problem, as I see it, is that once you've developed a bad habit and have no source to rely upon for correcting it you're likely to remain a mediocre rifleman.
IMO, there is no substitute for an accomplished shooting coach. Keep in mind that, even with the manual, the military provides expert coaching.
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