While I am not the top authority on Model 70's, one thing to keep in mind in this discussion, is that there are actually quite a number of different action styles, all called "Model 70's". They mostly all had the three position safety mounted on the bolt, and the same design trigger, until the advent of the new FN70, with the new trigger design.
As far as gas handling characteristics of the "Model 70", I have never read Frank de Haas book, but assume he is referring to the "pre-64" action. In this action, escaping gases could come back through the left raceway, and directly into the shooters face. The despised redesign of the Model 70 to a push feed style in 1964, has a bolt face very similar to a Remington 700, except for a better extractor, IMHO.
So I don't think this problem exists in the push feed style Model 70's.
The "Classic" CRF action introduced in 1990, while very similar to a "pre-64", is not identical and does incorporate some improvements over the "pre-64". One is a gas block, which resides on the left side of the bolt opposite the non-rotating extractor. This serves to block the left raceway, in the event of a case rupture, to help prevent hot gases from flowing back through the left raceway. Newer production Classics, starting in about sometime in 2002, also began incorporating a bolt shroud with a gas flange on the left side, which serves to deflect any gases which might escape past the gas block away from the shooters face. This flanged bolt shroud is seen on the CRPF action as well. The new FN70, a CRF action apparently identical to the Classic except for the trigger, also uses the gas block and flanged bolt shroud. Hope this helps to clarify some of these issues!
As far as gas handling characteristics of the "Model 70", I have never read Frank de Haas book, but assume he is referring to the "pre-64" action. In this action, escaping gases could come back through the left raceway, and directly into the shooters face. The despised redesign of the Model 70 to a push feed style in 1964, has a bolt face very similar to a Remington 700, except for a better extractor, IMHO.
The "Classic" CRF action introduced in 1990, while very similar to a "pre-64", is not identical and does incorporate some improvements over the "pre-64". One is a gas block, which resides on the left side of the bolt opposite the non-rotating extractor. This serves to block the left raceway, in the event of a case rupture, to help prevent hot gases from flowing back through the left raceway. Newer production Classics, starting in about sometime in 2002, also began incorporating a bolt shroud with a gas flange on the left side, which serves to deflect any gases which might escape past the gas block away from the shooters face. This flanged bolt shroud is seen on the CRPF action as well. The new FN70, a CRF action apparently identical to the Classic except for the trigger, also uses the gas block and flanged bolt shroud. Hope this helps to clarify some of these issues!


















































