Definitive Guide to Gamo Magnum GR

Gamo USA is going back to an old-school breakbarrel design with their Magnum GR. Not only does it have an all-steel receiver, breech block, and barrel, but the powerplant consists of a traditional metal spring. More on that later.

The Gamo Magnum GR pellet rifle weighs 6.88 pounds, has a barrel of 19.7", and is 49.2" in length. The stock is the same lightweight thumbhole ambidextrous synthetic stock found on Gamo's previous magnum class airguns, like the Swarm Magnum Gen 2 and Gen 3 variants. There's a tall cheekpiece that's ideal when using the bundled optic, but it's too high for the open sights, making them essentially unusable. This is unfortunate for those wanting to use open sights out of the box. However, there's some good news on this front. Gamo USA is working on a replaceable cheekpiece that can be swapped with the tall module, making it shorter and ideal for use with open sights. This optional accessory will hopefully be available directly from Gamo in the near future. There's decent stippling on the grip and forearm, which provides a good grip.

As mentioned above, the action is all metal, including the breech block and barrel. There's a noticeable lack of Gamo's traditional Whisper moderator at the front of the barrel. Rather, you'll find a simple fiber optic front sight with a metal globe. As you track backward toward the receiver, there's a fully adjustable fiber optic rear sight. On top of the receiver is Gamo's "Recoil Reducing Rail," which provides an 11mm mounting point for the bundled optic. There's a stop pinhole at the back of the rail to help prevent scope slippage.

Other features include the 2-stage CAT trigger, which allows for some adjustment, the SWA (Shock Wave Absorber) recoil pad, manual safety, and an impressive 5-year warranty. Gamo's standard 3-9x40 scope and one-piece mount are also bundled with the Magnum GR. It features a 30/30 duplex reticle and a fixed parallax.

Setup & Operation

Mounting the scope is very straightforward, and there are clear instructions included with the Magnum GR. The important part is to make sure that the stop pin on the mount lines up correctly when attaching the scope. Be sure to tighten all the screws on the one-piece mount to secure it to the rail. Once the scope is secure, check the reticle alignment and eye relief. If everything looks good and is comfortable, then make sure that the scope rings are also secure. Be sure to use an X pattern and tighten them down evenly. You may need to adjust the angle and the position of the scope in the rings. Take your time, and always make sure that everything is tight before you take your first shot.

The Gamo Magnum GR is a traditional, single-shot, spring-powered, breakbarrel air rifle. The cocking effort tops out at around 41 pounds. Fortunately, the metal spring builds pressure as you go, so the cocking effort doesn't start at that full 41 pounds. Once the gun is cocked, you need only load in your .25 caliber pellet of choice, close the barrel, release the safety, point the rifle at your intended target, and gently squeeze the trigger. To fire again, simply repeat the process.

The trigger pull weight is about 2.5 pounds. It's smooth and predictable, although we'd prefer a shorter second stage. While Gamo's CAT trigger is "adjustable," you can only adjust the position of the first stage and can't adjust the length or weight of the second stage. It's not a match trigger, but it's a very usable field trigger.

With regards to noise, the Gamo Magnum GR does not feature a shrouded barrel or moderator. However, most of the audible sound comes from the mechanics and not the shot. And since there's really no way to quiet that down, the lack of a suppressor doesn't really impact performance. We didn't find the Magnum GR to be offensive in any way and suspect that it should be perfectly fine for most backyards, provided your backstop is also designed to be quiet. If you plan to shoot into a steel pellet trap, the pellet impact may be louder than the .25 caliber Magnum GR.

Performance & Accuracy

The Gamo Magnum GR uses Gamo's most capable 33mm compression chamber, which should, in theory, deliver excellent power and velocity. Gamo reports a max velocity of up to 1000 FPS with lightweight alloy pellets at sea level. Our testing facility is over 4000 feet. Because the air is thinner here, the volume of ambient air in the compression chamber is less than at sea level and can't make the same energy. We still did OK, posting a maximum velocity of 909 FPS with a 16.54 grain GTO domed pellet. We guess that using the 14.4 grain Gamo PBA .25 cal pellets at sea level would get us a lot closer to that 1000 max FPS. Even at our 4000+ foot elevation, our GTO pellets pushed past thirty foot pounds, which is a great result.

Now, let's get down to what really matters, and that's accuracy. We tested three pellets at 25 yards, starting with the 26.54 grain JSB Hades. They produce 691 FPS and just over twenty-five foot pounds at the muzzle. The group was decent and certainly would deliver a definitive kill shot at 25 yards.

Next, we looked at the 26-grain Predator Polymags. They shot at 691 FPS, producing over twenty-seven foot-pounds at the muzzle. The group was a little larger, but all the shots stayed in the black. As with the Hades, if you were hunting small game at 25 yards, you'd be all set.

Lastly, we tested the Predator GTO lead-free pellets. As mentioned above, they are 16.54 grain, shoot over 900 FPS, and deliver over thirty foot pounds of energy at the muzzle. They also produced the best group at 25 yards. It may be a toss-up between the Hades and the GTO pellets. Either way, if you were looking for a hammer of an airgun for close-range work, the Gamo Magnum GR .25 caliber can get the job done.

Summing Up

So that's our definitive guide on the Gamo Magnum GR .25 caliber, old-school airgun. It's certainly capable of pushing some impressive power. The traditional metal spring is about as reliable as it comes, and for those out there who like to tinker, it's an opportunity to get back to airgun tuning basics.