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Gamo R77

I was talking to a new shooter who had dropped by to discuss the purchase of an air pistol to train his wife to shoot. I showed him the venerable Crosman 38C. Designed to mimic the Smith & Wesson model 19 revolver, there is little this old favorite lacks in the way of a fun gun. It’s a six-shooter with both single and double action, plus it has reasonably decent accuracy to 20 feet, or so. It’s ideal for training a beginner without the noise and range requirements of a firearm. The only drawback for the fellow in my office this day was the size of the grip. His wife has small hands, which is why he bought her a Smith & Wesson model 10. Weren’t there any airgun revolvers with smaller grips?

I purposely selected the 38C because I knew it to be smaller than the current Crosman 357 magnum. In fact, until this request, I had always thought of the 38C as a small air pistol. It fits my hands quite well, though I admit I’ve seen some folks struggle with it. But if that’s all there is, what are you going to do? A Brocock air pistol might work, but at a cost of hundreds of dollars, not to mention the fuss of charging the individual cartridges with air all the time. What to do, indeed.

Gamo has the answer. Their R77 is a nifty eight-shot CO2 revolver with a true swing-out cylinder that gets loaded from the rear. It comes in .177 only, which is fine for its intended purpose as a fun gun.

We bought ours from a Gamo distributor, Catoctin Cutlery in Maryland, because Gamo dealers weren’t stocking the R77, yet. Hopefully, that has changed by now. At $80 retail, this is a great little training gun for new shooters.

Velocities were taken with lightweight wadcutter pellets, which seemed suited to the power available. We recorded the following: Temperature…75°F Shots…10 Distance to start screen…Point blank RWS Hobby Average velocity 323 f.p.s. Extreme variation 5 f.p.s. Standard deviation 1 f.p.s. Gamo Target Average velocity 313 f.p.s. Extreme variation 18 f.p.s. Standard deviation 6 f.p.s. Crosman Copperhead Wadcutter Average velocity 298 f.p.s. Extreme variation 11 f.p.s. Standard deviation 3 f.p.s.

Because of a unique cylinder design that I’ll reveal in a bit, I seated all the pellets deeply into their chambers by grasping the front of the cylinder with my fingers and pressing against the pellet base with the tip of my thumb. That way, there was no pressure put on the cylinder crane. The big Hobbys had a definite feel when they finally overcame the resistance of their skirts and entered the chambers completely. Note that they also turned in the highest average velocity and the lowest spread. I think I know why.

Velocity drops if the shots are fired quickly, one after the other. By waiting 15 seconds between shots, I found that the velocity stabilizes for every pellet.

Unlike many CO2 revolvers, the R77 appears to have no copper or brass pipes in the gas delivery system. The gas flows directly from the powerlet in the grip through the valve and out into the chamber. Gas pipes are the second most common cause of leakage, after the use of improper oils. By omitting them, Gamo has made this a more reliable gun. I don’t think there is even one O-ring in the whole gun. We left ours charged for two months with no discernible loss of gas.

One weakness the gun has at present is the method of attachment of the right grip panel, which comes off to install a new powerlet. Gamo has chosen to fasten this panel with two plastic clamps cast into the grip. Just the strength of the plastic alone holds the grip to the gun by clamping onto the powerlet. Looking at how much those clamps have to flex, I predict they will eventually break. I would prefer metal for this job.

I didn’t expect this revolver to be an aspirinbuster— and it isn’t, of course. But at 10-15 feet, it will destroy a 1/2-inch bull with astonishing regularity. A single cylinder of eight pellets will remove all evidence that the bull was ever there. If the shooter gets too cocky and starts to “rattlebattle” with the double action feature, however, the shots will walk to the side opposite the shooter’s hand (i.e., a right-hander will string shots to the left). You CAN shoot this pistol with two hands, but why would you want to? It’s so light and easy to hold.

The rear sight is adjustable for both windage and elevation. And, a hammer-blocking transverse safety is located just behind the rear sight. It blocks the hammer from making contact with the valve seal, thus firing the gun. Even more amazing than that—Gamo engineers have incorporated a transfer bar in the hammer mechanism, so if the hammer accidentally falls, it won’t open the valve unless the trigger is also pulled back.

This is an extremely small air pistol. It’s sized much like the Smith model 10, which is a smallframe revolver. What you can’t see in the picture is the trigger pull, which is very nice in both single and double action. Oh, it’s no Colt Python, but it’s pounds lighter than the Crosman 38-series revolvers. You could do a lot of serious training with it!

One thing that threw me for a loop was that the cylinder doesn’t lock up positively except through the trigger. That’s right—there is no locking bolt! Pressure on the trigger advances the cylinder by means of the part called the hand, and that same part also locks the cylinder in place when the hammer falls. I am amazed that the thing indexes correctly; but after several hundred shots, I’m beginning to see how clever this design really is. It wouldn’t work for a firearm, of course, but it works fine for the relatively low pressure of carbon dioxide. All Gamo has to do is control the precision of their molding process, so the indexing notches in the rear of the cylinder are always in the right place, relative to the cylinder bores. It does seem strange to be able to turn the cylinder freely at all other times, though—kind of like the cylinders on the new-model Ruger single actions that go limp when the loading gate is opened.

Another question that I had concerns the long freebore the pellet must pass through (the entire cylinder) before jumping the gap to enter the barrel. You see, when you chamber a .357 round, the bullet is at the barrel end of the cylinder, making this jump a short one. But in the Gamo, the pellet starts at the back of the cylinder and has to traverse its considerable length before jumping across the gap into the barrel. That ought to make for lousy accuracy, not to mention low power. Well, the power IS a trifle low, but the accuracy isn’t half bad.

Actually, the cylinder isn’t a freebore at all— IT’S RIFLED! This is the first revolver I have ever seen with a rifled cylinder. And that rifling is in addition to the rifled steel barrel. The plastic (I’m sure there is a more technical designation for this stuff) cylinder has six narrow, but very deep, lands that engrave the pellet’s head as well as the skirt. My eyes could detect no twist rate, but if it is there, it’s a slow one. Even if it’s a straight twist, though, it still upsets the pellet skirt enough to obturate the bore quite well. Since the rifling holds the head firmly, there is no chance of the pellet tipping as it jumps the wide gap to the barrel. And, by making the entire cylinder from what is, I’m certain, a very low-friction material, they get as much velocity as possible from a small CO2 pistol. THAT is the secret I alluded to before, and it’s why you must seat the pellets deeply. This thing is really well designed—way to go, Gamo!

The cylinder/barrel gap on our test gun is something like .020", which is three times more than normal on a firearm. The long 1.610" cylinder is really where the pellet gets all its energy, so this gap isn’t as serious as it sounds. And, the generous gap allows Gamo to keep the manufacturing rate high without jeopardizing performance. The barrel is funnel-bored to catch the pellet and guide it into the second set of rifling. The real barrel has a slow but, I believe, detectable right hand twist. Not a design to copy for a target pistol, but it works well in the R77. With a company this clever, can it be long before they resurrect the Rast & Gasser gas-sealing cylinder design and up the potential velocity even more?

The rear of the R77’s cylinder has a gap, as well. There is a large visible space between the end of the gas valve and the start of the cylinder, where the pellet sits. This means that the CO2 force is very much dissipated before it hits the rear of the pellet. Still, Gamo found a way to make it work, because there is no denying the performance level of the gun. One wonders, though, what a short protrusion from the front of the valve face might do for things.

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