What production or custom rifle, scope, and scope mounts would you choose for an ultralight mountain rifle? The gunsmith who mounted the scope took it to the range and said it shoots sub-MOA (as advertised), so that's something.
It no doubt did shoot sub-moa at 100 yards. That has little to do with how it will shoot at 500 to 1000 yard distances.
The typical unaided human eye can resolve about 1 arc minute. At 1000 yards one arc minute is about 10 inches diameter. What do you expect to shoot at 1000 yards? Moose? Prairie dogs? Something in between? What diameter kill zone do you need in inches and MOA? What conditions will you shoot in? Between sunrise and sunset?
Where can you loose weight on a hunting rifle?
1. The stock: McMillan sells carbon fiber hunting style stocks inletted for most actions. That won't hurt accuracy at all, at least if you shoot supported.
2. The barrel:. Longer barrels flex more. Smalller diameter barrels flex more. Larger calibers with heavier bullets flex more. A 20" featherweight barrel with a well designed contour
and a modest cartridge should work well.
3. Cartridge. My choice would be a 6.5 Creedmoor 6.5x47 Lapua as they will fit in a short action and still allow shooting VLD moderately heavy bullets, which are essential for good wind performance at ranges to 1000 yards. YOU need to decide what terminal energy YOU think you need for the game you wish to shoot.
3. The scope. Between sunrise and sunset a 6x30 scope will give enough resolution that the scope will not be the limiting factor for shooting 2" groups. The rifle, the ammo and particularly any downrange wind WILL be more limiting than the scope.
As others have suggested you need to practice. For any "long range" shooting wind deflection is the major problem to overcome. The weight of the rifle has no effect on that.
It's determined only by bullet velocity, bullet BC, and YOUR ability to determine how much the ambient wind condition between you and the target is going to deflect each shot. Only practice and the resulting skill will allow you to know your capability and limits in various conditons. It's not something you can buy.
Start by practicing with the rifle you have. So what if it's a pound heavier than you think you want to eventually want to carry. Don't buy anything except ammo which has low drag bullets which will fit in your rifle until you learn to >regularly< hit kill zone size targets. Paper plates make decent targets. Set them in safe locations at assorted ranges. Practice at a range at 100 or 200 yards is useless for learning to dope wind. You need to practice at the distances and conditions where you expect to eventually hunt.
