The way the Accurate weapon quality is written makes it a little absurd.
Let me show you how.
Standard Stan (a Weapon Specialist) has a Ballistic Skill of 30, the average for a starting character. He raised that by 5 for his Specialization. Now, let's hand him a Sniper Rifle.
Stan takes a Half Action to Aim, gaining a +10 to hit. The Accurate quality on his gun boosts that to a +20. He then must fire it Single Shot, as his Sniper Rifle lacks another mode of fire, raising it to +30. He's now rolling under a 65 to hit (at character creation!), with any roll under 45 dealing 3d10+4 Pen 3 (average damage on that is 17).
With just his starting XP, he can raise his BS to 45, bringing all this math up to 75. If he keeps throwing XP at it, and acquires the rather common (Scarce availability) Red-Dot Sight, you're looking at a 95% chance of hitting for 3d10+4 damage. Grabbing a Custom Grip brings us to a clean 100. While this is a rather hefty investment, it is certain to top anyone else in the party by far.
I'm not prone to calling "broken," but this just seems a little too easy. A sniper rifle or long-las is going to add +30 BS almost every round, which nearly guarantees the extra damage. I'm alright with the bonus to hit, but perhaps lowering it or removing the bonus damage would be smart.
(Fun thought exercise: BS 40 (maximum starting) +5 (Weapon Specialist) +20 (spending XP) +10 (Single Shot) +20 (Half Aim and Accurate) +10 (Red-Dot Sight) = 105% chance to hit, before adding in possible bonuses from Regiment)