True all Model 70 actions were the same length and the H&H length was achieved by removing metal.
Same was done with many of the '98 Mauser actions. The MarkX, Whitworth, Santa Barbers and most of the English and German small shop builds, and even some of the larger firms used "Standard" length Mauser actions simply opened up to accept the longer length.
Metal is always removed, but if done correctly safety will not be compromised, but of course the action is a bit weaker.
Some look at the bottom lug of the Mark X in the H&H length and it's almost knife like top edge of the lower lug and shudder....but as far as I know they have never failed as a result of the modification.
The Savage 110 is another example of a standard length actions being opened up to accept H&H lengths, although that metal was only removed from the rear of the action just ahead of the bolt. I believe after the mid '90's all of the Savage 110's so called standard length actions were long enough to handle the longer cartridge. I believe that mostly came about when they started chambering the RUM and STW cartridges, for production cost reasons. If you look at a 110 pre mid '90's you will see about 3/8" of metal just ahead of the bolt when it is at the rear of it's travel, in later models that metal is gone, hence the longer length.