Reviewed: GAMO Swarm 10X Viper Gen 3i

Need an air rifle capable of ripping through cans and drilling targets with precision? Take a hard look at the GAMO Swarm 10X Viper!

posted on April 27, 2023
Gamo Viper 10X Lede

After what seemed like a drought of decent newer airguns to test and write about, I found myself pulling a GAMO Swarm 10X Viper out of the box. I had used a GAMO product similar to this one for another review two years ago and I loved that gun. Would the Swarm 10X Viper Gen 3i make the cut? 

My first order of business was to read the manual and then mount the scope on the air rifle. Seven shots was all it took to sight-in, and I was a very happy camper. The drought of good airguns was over ... I had a shooter! I then began testing various pellets to find the best match up.

I shot four different pellets to include brands other than GAMO, and found that the GAMO Rocket .177 pellets in 9.6 grain were by far the best. Not only did they shoot very accurately, but they hit really hard. I could hear a difference in the cans when shooting. The hardened steel tip, which looks like a BB on the nose of the pellet, was probably the reason. Another reason the Rocket would be my recommendation is that these pellets load easily and very consistently in the magazine. Some of the other brands required some extra effort to load in the magazine, and I have to wonder if that may have impacted accuracy of the rifle.

My test was straightforward and simple. I sighted the rifle in at 20 yards, and then started experimenting with the rifle and pellet combinations. I also shot at longer ranges; I shot cans and some wood boards.

I have to admit I get distracted at times and mess around which leads me to some unique field situations. For instance, once I knew where the Rocket pellets were hitting, I started shooting at oddball things at various distances on my range. We live in a very rural area with the nearest neighbor nearly a half mile away, so I have plenty of room to shoot.

After firing at the target and getting a photo of it, I noticed some raspberry canes that were bright red along the range. I wondered if the gun was accurate enough to cut one. The first shot answered that question. The cane was broken off at a 90-degree angle! Some gumballs from a nearby tree were made to dance, and an empty shotgun shell was fair game too. Fun stuff! If it had been squirrel season I think I would have taken a walk to see what would happen with that.


  • 1300 fps with alloy pellets, slower with lead
  • 2 stage adjustable trigger
  • Inertia fed, 10-shot, auto loading magazine with clear indicator how many pellets remain (I recommend getting a second magazine for more fun)
  • Break barrel
  • 3x9X40 scope
  • Whisper Maxxim Gas Piston that reduces the sound of the gun going off (think nosy neighbors or hunting situations)
  • Fluted polymer jacketed rifle steel barrel

Positive notes

Besides the factors I already mentioned, there are some observations I made while testing this rifle. After testing dozens of airguns the past few years, I found this one much easier to cock than many others. That is a huge plus, particularly for those who are younger, those without long arms, those without a lot of upper body strength or other physical limitations. The grip on the fluted barrel helped.

The gun is pretty quiet. It is not the quietest gun I have ever tested, but definitely far from the loudest and very comfortable to shoot. The noise won’t bother anyone. I would equate it to a smack on a fenceboard. The scope was easy to mount and very easy to get sighted-in. It is clear and straightforward to use.

The magazine is good. Users can tell at a glance how many shots are left. Most airgun magazines are a bit tedious to load .177 pellets due to the size of the pellets, but this magazine is easier than most. I would strongly suggest finding a pellet that is easy to push down into the magazine. Start with GAMO pellets, as my tests show they do load easier and shoot more accurately. I would also get a second magazine if you shoot a lot or hunt with it.

Accuracy is very good. Often I was ripping one big hole. The photo with this article shows an average group or possibly one that is slightly less than my average group and it was still spectacular, (particularly since I am confident that the one "flyer" was my fault. I would have no problem shooting varmints or small game with this gun out to 40 yards or so, possibly farther.

The trigger was good right out of the box. I tested it and found the pull was right at 3 pounds. That is a very nice feature. It is adjustable, but I never bothered given how good it was already.

As for cons? I would have appreciated a spare magazine (even if that meant a small bump in price). My biggest problem with this rifle now is keeping it secret from my daughters and some of the kids that are in the outdoor club I run! I think I will have to hide it. Parents, if you have a teenager that is responsible and enjoys accurate shooting or even small game hunting, this is a great rifle. Adult shooters, this rifle is high quality fun. For more information, visit!


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Henry Americanlegion

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