My girlfriend's old man has had this rifle for quite some time now, although I haven't got to shoot it much. Last week I was home alone all week and I can say with absolute confidence and authority: THIS THING IS FREAKING AWESOME!!
The 350 Magnum is not the rifle to buy your 6 year-old boy. It is a full sized rifle at 45 inches, and it's power comes at the expense of a very heavy cocking pull. It's lucky that the barrel is relatively long and increases leverage otherwise the Diana would get very tiring very quickly. The .177 version spits out pellets at about 1250fps and its bigger brother propels .22cal pellets at just under the sound barrier - about 950fps. At over 8lbs, it could also get too heavy for a youngster to hold for extended periods. These 'drawbacks' are well and truely worth it however; this thing will kill varmint sized gamed like the hand of god himself out to 50 yrds.
Open sights come standard, and are capable of accurate headshots on rabbits out to 30 yrds. The front sight consists of a hooded, replaceable red fluorescent bead while the rear sight is a dovetail with green inserts either side. Simply place the red dot between the green ones and fire. The rear sight is adjustable for elevation and windage, a dab of loc-tite on the adjusting screw would be helpful as the considerable recoil can work them loose. A scope dovetail is also provided above where the acton would be on a normal rifle. The unadjustable trigger has a mile of creep, but is very easy to use once you get used to it. Without the creep it would be just about perfect; it breaks smoothly and unpredictably. The 350 Magnum also has an automatic tang-mounted safety, and I will say this now, you will miss shots because of it
It comes on as soon as the rifle is cocked, and to release it all you have to do is push it forward, however I was constantly forgetting about it when lining up game.
The 350 Magnum will drive Gamo Match Pro pellets about an 1/8th of an inch into a block of aged redgum firewood at 25 yrds. 5 shot group sizes ranged from .5 - 1 inch. Sighted in to hit ~1 inch above POA at 25 yards, the Magnum will still reliably kill currawongs, rabbits and crows at least 50 yrds. Any of these varmints hit in the abdomen region within this range were DRT. I tried for longer shots but they were pretty hit-and-miss on the small game. I'd say that within 50-60 yards it would kill small game just as reliably as a rimfire .22.
Price is about $750 down here, no doubt it's much cheaper there so if you're looking for a quality, full-sized hunting .177 or .22 air rifle, you'd be well advised to look very hard at the Diana 350 Magnum.