Do any other actions with long claw extractors use the interlock feature that a true Mauser uses? How about the Remington 30, the Springfields, etc.? Was the Winchester model 70 the first rifle to do away with this feature? Does it really make a big difference with modern ammo?

I am not sure what your refering to by "true interlock feature", could you be more specific...all the models you mention are true control feed rifles, along with the Win. M-54, in that they pick up the case head about midway down the cycle and hold on to it to lockup and then maintain that strong purchase and extract it after firing...

The Brno ZKK and CZ 500 series also use this and they are the only ones that do, I am fairly certain.

Ray, I think that he is talking about the underlip feature in the collar recess on the Mauser bolt body; as you know much better than most, the Pre-64s and so forth did away with this.

IMO, this is a good feature and I would prefer to have it on a hunting rifle, but, since many of my most used rifles don't and have never failed me, I don't lose too much sleep over it. It's like the C-ring vs. the H-ring FNs, I prefer the former, but, I would dance with the latter.

OK, got it....Only a true Mauser has this feature and according to Jack Belk the idea is to prevent nonfunction from debris and gunk in that area...

I, like Kutenanyboy, have not had a problem with this feature or lack off this feature nor the double cut FNs but far be it from me to take on Paul Mauser, thats a exercise in stupidity...the man was a the ultimate genius of all geniuses....given me druthers I will opt for the feature if Paul Mauser did....