Hi
what is your opinion about building a cusatom DGR rifle on husqvarna commercial m98 actions? like 146 and 640 series. caliber would be 9,3x64 or 404 jeffey.
regards
yes

I have a 9.3 X 62 on a Brazilian 1908 and I don't see why your Husqvarna wouldn't be well suited to it. As far as the .404 goes, it could be done but, I wouldn't do it. I have a .404 I built on a Post 64 Model 70 that was a .300WinMag and that worked quite well. The magazine opening in the Model 70 was long enough to begin with and only alerations to the feed rails and a long magazine box were required for the conversion. With your Husqvarna, the magazine well would have to be lengthened by cutting both fore and aft. Taking everything from the front leaves too little backing for the lower locking lug, not to mention extensive feed rail work and opening the bolt face and altering the extractor. You would also need extensive altering of the existing bottom metal or purchase ($450-$500) new bottom metal for it.
If you want a .404 Jeffrey (and I heartily recommend it), get a action made for a magnum cartridge and better a long magnum cartridge based on the .375 H&H. The bolt face doesn't even need to be opened (although it could stand about .005" -.007" more open) and the box length is good to go. Mind you, all Post-64 70's in the long action have a long enough magazine opening and usually, all you have to do is alter/change the mag box and cut back the bolt stop and ejector.