Well, I've had my Gamo Sporter 500 for a couple of months now, so I figure it's high time I really scrutinize the thing. I had originally bought it for a number of reasons... it was only $60, I was trying to build up my array of medium-powered springers in anticipation of moving and losing my 60 yard outdoor range, and I wanted a decent "teen gun" for the occassional younger shooter that comes by. Besides, I wanted to see what it was like. I always had a soft spot for anything made by Gamo, and for all their flaws I never came across one that I really disliked (defective examples aside).
It turns out that the Sporter 500 is a bit of an oddball - almost a cross between the smaller Delta and the "regular" breakbarrel that we're all familiar with. At 43" long overall, it's right in there with the Shadow in terms of size, although at under 5.5lbs it's noticeably lighter. The stock is nicely finished for a cheap rifle with moderately pronounced grain, a ventilated rubber buttpad, and a smooth, even satin finish. Much better than the 220 stocks I've seen. The trigger is the standard adjustable Gamo trigger (with manual safety and anti-beartrap), not the non-adjustable version found on the Delta. The blued compression tube is nicely finished, with "Gamo", "Made in Spain", and the serial number laser-etched on one side.
But as you move forward, things get a little different. The entire lockup mechanism and front yoke are plastic - it looks to be the same construction as used on the Delta. Ditto with the unusual breach seal arrangement - the "O" ring is actually on the stationary part of the action. The compression tube, by the way, doesn't have a closed end as such... it's bored all the way through. Part of the plastic yoke assembly actually fits into the front of the compression tube to seal it and is retained by two pins. Sitting on top of the breach is the old Gamo Shadow/220 rear sight (an improvement over the Delta's ramp-adjustable sight). The breach and the piston are connected via the normal Gamo articulated cocking link. Inside, though, there is no guide roller to keep the link from gouging the stock - but rather a simple plastic button just like the one on the Delta.
Inside the rifle the piston stroke comes in at about 88mm, compared to 100mm for the typical "full size" Gamo powerplant. The spring is almost a foot long, but the number of coils (38) and the smallish wire diameter (.115") keeps this spring about 20% softer than the Shadow-type spring. Preload is a little over 2", which translates into approximately 50lbs. The piston bore is the Gamo-typical 25mm, and appears to to use the normal Gamo piston seal.
The full size of this rifle sorta positions it solidly in the "teenage" age bracket and up (it's not a smallish youth gun like the Delta)... an impression that is reinforced by the effort required to cock this rifle. It peaks at about 26lbs, which is surprisingly close to the 30lbs required by my 220/440/Shadow rifles or the Crosman Quest family. I have a "detuned" Quest (with a lighter spring) that cocks with 24lbs - and delivers almost 40% more power. So I suspect that this powerplant isn't optimized as well as it could be. At least the trigger is pretty good on this example - it pops at about 4.5lbs - and will undoubtedly improve with use.
The absolute performance of the rifle shows it coming in a couple of notches below the "normal" Gamo, pushing 7.9gr Crosman Premiers out at about 650-660fps for about 7.5 ft-lbs of energy. Firing cycle on this example is lousy even for a Gamo, with LOTS of long-lasting buzzing and twanging from the mainspring. It needs some serious help in this department.
But it certainly needs no help as far as accuracy is concerned, and frankly this seems almost a foregone conclusion anymore with Gamo rifles. Initially I had little luck with the open sights... the front bead is much smaller than the rear notch, leaving a lot of room for it to "float around" while trying to aim. I just couldn't get consistent results with it, so I resorted to a scope.
At this point let me (once again) reiterate my poor marksmanship skills and wobbly aim... so that when I point out that this rifle had little trouble throwing a .2" 5-shot group at 10 yards, it is taken in proper context! That was shot with 7.9gr Crosman Premiers, which all my Gamo's like. Here I should mention that the short dovetails had trouble accepting the "C" mount that came with my Sierra Pro... the very ends of the mount had to bite into the curved part at each ends of the grooves. This gun will definitely prefer either a two-piece mount or a shorter one-piece. There's no provision for either a bolt-down scope stop or a stop pin, but the relatively mild recoil of this gun shouldn't make life too difficult for the mounts even without any extra help.
Obviously the rifle can shoot, which is really the final criteria on which a recreational gun of any sort will be judged. But the Sporter 500 still does has other issues that don't speak so well for it - specifically the heavy (for the power) cocking effort and the horrendous spring noise. So where does that leave it?
Well, generally speaking Gamo is never known to make a finely honed, well sorted gun... they are priced too low for that, especially for a European manufacturer. What they do, though, is deliver on the essentials. It's far easier to reduce spring twang than it is to cure a poorly finished barrel or compensate for a bad lockup design... so Gamo provides the essential foundation of an accurate rifle and leaves the rest to the owner.
As for the Sporter in particular, this description fits it well. Granted, there might be some reason to be concerned over the plastic construction in the critical yoke and lock-up areas of the rifle... after all, this gun does produce a fair bit more power than the Delta which uses similar construction. But we're gonna have to take Gamo's word on this... and the gun's performance with a scope would indicate that the plastic lockup mechanism is quite adequate (as long as it doesn't break). Some years back Gamo used to make guns very similar to this one for Daisy, plastic yoke and all, and I haven't heard reports of stress failures in those rifles. Perhaps others have, I'd like to hear about it.
All in all, the Sporter makes a very acceptable moderate-powered plinker, especially at $60. It's far superior to the Crosman 795, and it's not gonna tear up a cone trap the way a Shadow or Phantom will. Although the cocking effort is rather high for the power, it's still an "all day shooter" for anyone near adult strength.
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After thinking about it for a while, I couldn't help but wonder what a different spring might do in this rifle.
The first thing I tried was a Crosman Quest spring (C1K77-010), which tends to have a tighter fit over Gamo guides. Well, the fit was tight, and it was very difficult to get on. When inserted into the gun, the spring didn't have much preload so it was fairly easy to install. Unfortunately, the spring was obviously TOO tight, and it graunched annoyingly on the cocking stroke. The added friction caused a peak cocking effort of almost 30lbs, while power dropped to about 590fps. The only upside was the firing cycle - predictably, all twang was gone.
The next step was to try a stock (used) Gamo Shadow-type spring. It was a little looser on the guide than the Crosman spring, which eliminated the excessive friction exhibited by the Crosman spring. Again the preload was nominal, and it delivered about 630fps with virtually the same cocking effort as the original spring. For reasons which are not quite clear, however, the firing cycle is still a lot calmer, although not quite as "tight" as the Crosman spring.
It is very tempting to leave this last spring in place, but to work at it's best the gun really needs a new guide for the stock spring. Perhaps some day I'll get around to making one. But there's no hurry - buzzy or not, the gun is a very capable shooter, and as I mentioned earlier, that's really what counts.
