A battle where I tested out critical hits with my brother:
(This requires you to have the VS recorder to see, connect to the internet and punch in the codes)
My persective:
GZ9G-WWWW-WWWX-E8VU
His perspective (Watch this so you can see how much HP is lost on both non-crits and crits):
FWZW-WWWW-WWWX-E95Y
Skorupi with Sniper had 40 SpA is the male skorupi. Spamming Venoshock against Solrock (78 SpD) and Minun (94 SpD)
Critical Hit lands on minun on turn 10
Skorupi with Battle Armor had 45 SpA and is the female skorupi. Spamming Venoshock against Zangoose (71 SpD)
Critical hit lands on Zangoose on turn 4
Also, for the lols this confirms that using Trick room twice resets the dimensions.
You may now at least have a rough range on how much crits (Both with and without Sniper) do. Get to it.
Expanding on this with information so you don't need to watch the replay:
Skorupi with Battle armor:
Non-crit hit 1 vs Zangoose = 27 dmg
Non-crit hit 2 vs Zangoose = 28 dmg
Non-crit hit 3 vs Zangoose = 25 dmg
Crit hit vs Zangoose = 40 dmg
Averaging the non crits ((27+28+25)/3) =26.67
40/26.67 = 1.499, which is 1.5x. So Its safe to say they nerfed crits to do only 1.5x damage now.
And with nerfing of crits means nerfing of Sniper. Kind of. Sniper didn't really change, it just multiplies with a 1.5x bonus to the base critical multiplier (Which used to be 2x, but is now 1.5x)
Skorupi with Sniper:
Non-crit hit 1 vs Minun = 19 dmg
Non-crit hit 2 vs Minun = 19 dmg
Non-crit hit 3 vs Minun = 18 dmg
Non-crit hit 4 vs Minun = 18 dmg
Crit hit vs Minun = 40 dmg
Averaging the non crits = 18.5
40/18.5 = 2.1621621...
Because my damage output against minun is so low, the numbers aren't exactly friendly enough to give it perfect accuracy, but I'm leaning towards it doing 2.25x damage.
So instead of sniper doing 3x, it now does 2.25x damage.
Proof of this is in the quote, watching that battle from my brother's perspective will allow you to see Zangoose/Minun HP. Zangoose and Minun's Special defense, as well as my skorupi's Special attack, are also in the quote.