Welcome to Sig Talk! SIG's Virtus is a great rifle with lots of setup options. I've enjoyed our Patrol and SBR MCXs with 5.56 and 300Blk setups. Am assuming you're starting with a 16" Virtus in 5.56 caliber. Also given your optic type, this rifle's primary targets are 100yds plus.
Here's our 16" 5.56 Virtus setup for longer targets, with S&B's 1-8x24MM scope.
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Virtus' short stroke piston system has many advantages, however weight isn't one of them - They're heavy up front. So, mounting a heavy optic probably isn't a great approach. IMO, quality glass in a 1-8 or 10 x24mm optic provides the greatest 5.56 range without adding an annoying heft to the rifle. Schmidt & Bender isn't in the budget, but there are some nice Nightforce, Trijicon, Vortex, etc. 1x8s that could serve you very well. Here's our rifle's weight with 1-8x24MM optic and M4 style butt stock.
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A much lower priced optic is Primary Arms 5x Prism optics. These aka 'Poor-man's-ACOG' are super tough with fine glass for their price. Sure, those 300yd targets won't look the same as with that 8 power scope, but for $350 - It ain't bad! Here's our 16" Virtus with PA's 5x Prism.
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I'll suggest POF's Roller Cam Pin
. It's an inexpensive and surprisingly effective trick to smooth these piston action's cycle. You'll notice the difference hand cycling your rifle right away.
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MCX Virtus heavy profile (SOCOM) barrel is built to last with very high round counts. After running thousands of rounds here, Virtus has much better precision with heavier projectiles. You won't be happy with MCX target groups running typical 55g 223 ammo - She much prefers the >70g stuff.
So, while you're waiting for the rifle, pickup some accessories & ammo during holiday sales.
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Hope this helps!