Fixed weights of .300 firearms.

Ref CleverRaven#34830

data/json/items/gun/300.json

@@ -7,7 +7,7 @@
     "name_plural": "M2010 ESR",
     "//": "http://www.guns.com/2012/05/17/remington-xm2010-army-sniper-system-esr-now-in-stores/.",
     "description": "A bolt-action, box-magazine-fed, sniper rifle chambered in the powerful .300 Winchester Magnum round.  The M2010 had completely replaced the M24 rifle series by 2017.",
-    "weight": "4002 g",
+    "weight": "5500 g",
     "volume": "2750 ml",
     "price": 1701000,
     "to_hit": -1,
@@ -29,7 +29,7 @@
     "name_plural": "Weatherby Mark V",
     "//": "MSRP, believe it or not.",
     "description": "The Weatherby Mark V is one of the finest bolt action rifles.  Designed in 1955 by Roy Weatherby and Fred Jennie, it has a strong action designed to safely fire high-pressure cartridges.  These rifles were presented to celebrities as part of a marketing campaign.",
-    "weight": "4200 g",
+    "weight": "3730 g",
     "volume": "3 L",
     "price": 259500,
     "to_hit": -1,
@@ -51,7 +51,7 @@
     "name": "Winchester Model 70",
     "name_plural": "Winchester Model 70",
     "description": "The Winchester Model 70 is a bolt action sporting rifle.  It has an iconic place in American sporting culture and has been held in high regard by shooters since it was introduced in 1936.",
-    "weight": "4100 g",
+    "weight": "3520 g",
     "volume": "3 L",
     "price": 46000,
     "to_hit": -1,