I have the V4 on a T/C Encore .45 Cal. Smokeless Muzzy. I am shooting a 275 grain Sabotless bullet @ 2600 fps. I am also using the Zeiss Precision Scope Rings which are very high-quality rings. I have not had any issues whatsoever with the V4 on this rig.
Not trying to confuse you on your 2 choices but you might want to look at the Trijicons also. Trijicon Tenmile HX....... https://www.trijicon.com/products/subcategory/trijicon-tenmile-hx-long-range-riflescope
The V4, SHV and the Tenmile HX are all made in Japan as well as the NF NX8
The NF you are speaking of is a 56mm not 50mm if that makes a difference to you. I have 2 Smokeless Powder Muzzy's, 1 with a V4 3-12x44 and 1 with a NF NX8 2.5-20x50. Both are solid choices and I have not had an issue with either one. I did also have a SHV 5-20 on a previous build and never...
When I had my Savage my go to load was the 300 grain Barnes Original (.458) with a Harvester Black Crush Rib Sabot, Fed. 209A and 67 grains of Reloader 7 Powder. My gun had a "loose bore" from the factory. I tried a dozen different combinations of bullets and sabots and powders and was never...