The Gamo DynaMax repeater – Part 1
by B.B. Pelletier
Today, we’ll start a review that some of you demanded. You were interested in the new DynaMax from Gamo, and you really wanted to see it put through its paces. Here we go.
The Dynamax is a repeating precharged pneumatic rifle (PCP) that currently comes in .177 caliber, but which is also scheduled for release in .22 in the future. The .177 rifle is advertised as achieving up to 1,200 f.p.s., which I have to assume was with a PBA non-lead pellet, so I’ll test for that. With that kind of power, I suspect we’ll see velocities in the high 800 f.p.s. or even the low 900 f.p.s. range with heavier pellets such as 10.2-grain JSB Exacts and 10.6-grain H&N Baracudas. That’s just about ideal for the .177 caliber because it extracts all the energy the rifle has to offer without going over 1,000 f.p.s. and losing accuracy. I plan to test a wide range of different pellet types.
The rifle has a charcoal gray synthetic stock that’s not ambidextrous. It fits me very well, and my sighting eye is elevated to the right part of the scope’s eyepiece by the high cheekpiece. The barrel is so clearly free-floated that it could serve as the dictionary illustration for that term. The barrel is just under 19 inches in length, but a compensator adds a bit more.
The weight is 8.75 lbs. if mounting the scope Gamo includes with the gun. Since a scope is required, that is a good weight to use. The stock sports quick-detatchable sling swivel studs, which hunters will enjoy. Overall length of the rifle is 38.25 inches, so it’s very compact–almost carbine size except for the weight.
The DynaMax is a black-on-black rifle. That makes it very difficult to photograph. Flash is out because of the hot spots it creates. I want to show you some details on the rifle, so I’ll be painting the subject with light as I go. That relieves me of the need for a lengthy setup with a balanced background, which is the professional way to do what I’m doing. I’ll describe in each photo how I took it.
I have to comment on the obvious BSA lineage. This repeater has strong familial ties to the BSA Hornet single-shot PCP. The tipoff for me was the cocking button in front of the forearm. That was handed straight down from the Hornet and all its offspring. So, this gun isn’t cocked like a typical bolt-action, even though that’s exactly what it is. To cock the DynaMax you press the steel button straight back with the fingers of your off hand until the sear catches.
The rifle I’m testing arrived without an owner’s manual, no doubt because I was sent an early model to evaluate. However, knowing its BSA heritage I suspected the fill pressure would be 232 bar, and it turns out that was correct. That pressure translates to 3,365 psi, a pressure that many U.S. scuba tanks and hand pumps cannot reach. Fortunately I still have a Hill pump, obtained when I tested the last Hornet derivative, a BSA Tech Star. Being British, the Hill had the correct 1/8″ BSPP threads at the end of the fill hose for the DynaMax fill probe to connect to. So, I was able to get a full charge for my testing.
If you have a 3,000 psi air supply you will still be able to fill the rifle and get maximum power; you just won’t get all the shots it’s capable of. You will fill to the middle of the power curve somewhere, which doesn’t mean lower velocity. It means fewer shots before it’s time to refill. I’ll try to sort that out for you in this report. Gamo says you get 30 shots at full power when the fill is also full, so the number gotten with a 3,000 psi fill will be somewhat less than that, I imagine.
Let me see….What about the DynaMax would you be most interested in? Why, the magazine, of course. In .177, it hold 10 shots and it’s rotary with a driving spring. The outer housing is steel and the inner cylinder is non-ferrous metal with two circumferential o-rings to hold the pellets in place in their chambers. Of course, with the cylinder residing inside the magazine housing, there’s nowhere they can go until they’re aligned with the bolt and the bore. As you load the magazine, you compress the spring, which will then unwind as the gun is fired, cocked and loaded again.
I find the magazine very easy to remove from the rifle’s receiver. It’s not a bit difficult. Just flip the bolt to the rear, pull out a magazine catch in front of the receiver and the mag slides out to the left. Load it with pellets, and it slides back in just as easily.
The DynaMax has no pressure gauge, so you have to count your shots to know when to refill. That’s why my info on the shot count at 3,000 psi will be so important. Hopefully, it’ll come close to a number of full magazines, probably two, since we know that the higher pressure fill gets about 30 shots. As you become familiar with the rifle you’ll also learn to hear when the shots are no longer on the power curve. They’ll sound both louder and longer.
I mentioned that the rifle comes with a scope. They include a very nice 3-9×50 Gamo variable scope with an illuminated reticle and its own mounts. The illumination is just a central dot, and you get red, green and blue colors with three brightness settings each. The dot is etched on glass, so there is no internal flaring of light at even the brightest settings. The duplex crosshairs do not light up, just the central dot.
This will make a terrific hunting scope, even for centerfire rifles on big game. But the dot in the center is so large that it covers too much area for precise grouping at 50 yards. It seems to cover more than an inch at 50 yards, making it perhaps a 2-mil dot. So, it’s perfect for hunters but not precise enough for tight groups at 50 yards. I’ll substitute another scope for the accuracy test. However, I do want to say that this is a very nice and capable hunting scope, and the glass-etched dot is a refinement that many hunters really need for low-light hunting.
Look at the lines of the stock in the first photo for a moment. Notice how vertical the pistol grip is. There’s also a scallop for the thumb in exactly the right place on the right of the pistol grip. Whoever designed this stock was a rifleman. I think the pistol grip, combined with the high cheekpiece, is why the rifle feels so natural to me.