Benjamin's Dual Fuel Discovery Air Rifle

Real Guns™ is a type 7 FFL holder. These days, whenever we put a gun together, it ends up being big and noisy and weighs twelve pounds. Sure, there is always the entertainment value of blanketing the nearby hills with a pressure wave of rolling thunder, but none of this hardware is appropriate for vegetable garden pest control or taking out critters that are attempting to make a winter home under the equipment shed. I was watching just such a fur ball marauder, sitting in a row of our carrots, going all Bugs Bunny on us, when I got the idea that we needed an air rifle.

I’m one of those guys who likes firearms to have an appearance consistent with their purpose. Subsequently, my deer rifles have bolts and walnut stocks and my defensive rifles are AR 15 types. So when it came time to select an air rifle for the purposes defined, something more traditional in appearance seemed appropriate. It also seemed reasonable to select a gun that used inexpensive and readily available pellets and did not need specialized equipment or process to keep it charged  with propellant. After some research, and after trying several manufacturers’ guns, I selected a .177 caliber Benjamin Discovery rifle and high pressure hand pump.

Located in Bloomfield NY, Crosman manufactures and markets air rifles and pistols under the brand names: Benjamin, Crosman, Marlin, Remington, and  Sheridan. While ownership has changed over the years, the Crosman company has manufacture red air rifles since 1924. The current product lines are populated with traditional and very modern air rifles and pistols that range in MSRP from $34 for the very basic, to $1,500 for the more exotic. The Discovery rifle is one of their more moderately priced products.

Despite the large selection, choosing a specific gun isn’t difficult. The Crosman site’s MatchMaker function  prompts with leading questions regarding price, performance and application criteria then renders a list of applicable and models. Products are also classified by types: PCP (Pre-charged Pneumatic), break barrel, CO2 rifles, variable pump rifles, and pistols. Each model is listed with recommended applications: target shooting, pest control and small game, varmint and/or predator hunting.

Crosman does a credible job of making application recommendations based upon a gun’s ballistic performance. No inappropriate match up between gun and game. No .177 PCP guns recommended for lion hunting, domestic or otherwise. Where they do list an air rifle for larger predators; coyote, bobcat and hogs up to 200 lbs, the recommended rifle is a .357 caliber repeater that launches a 145 grain Nosler bullets with 4,500 PSI of air pressure.

Overview and general operation…

 

The Benjamin Discovery .177 caliber rifle is available as a stand alone air rifle or as part of a kit that includes a high pressure hand pump. The pump is universal for this purpose and works with all PCP air rifles offered by Crosman. So if a times comes when a .22 or .25 caliber rifles is purchased, the same pump will service all. The pump can also be purchased independent of an air rifle for approximately $200, and can be used with many other brands of air rifles.

 

This Discovery rifle has a maximum operating pressure of 2,000 PSI, which is well within the supplied pumps 3,600 PSI operating capacity. The gun is dual fuel capable and may also be charged to lower power levels with a CO2 cartridge. Use of cartridges requires the purchase of a $47 adapter and, of course, the purchase of cartridges. As noted later, the number of shots that can be fired with one pump fill, and ease of use, caused me to believe the pump was the preferred propellant source.

 

The pump connects to the fill adapter at the front of the rifle that is stowed beneath a trim cap when not is use. The pump’s quick disconnect coupling is easy to attach and disconnect. A pressure bleed valve on the pump is opened after the gun has been filled, and just before the quick disconnect coupling is released, to depressurize the fill line. The pump and bleed valve cannot be used to depressurize the gun.

 

The V base can be mounted wide to the rear or front. I found that mounted as pictured, I was positioned directly over the pump handle and I could use my weight, rather than my extended back, to provide the bulk of the pumping effort. Important if you are like me and one hundred and six years old. Starting on empty, it took approximately 95 strokes to fully charge the gun. It was a good workout, but not extraordinary, and filling from 1,250 PSI, the gun pressure point where velocity begins to drop off, took only 35 to 40 strokes to recharge to 2,000 PSI.

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A gauge embedded in the rifle’s forearm tracks pressure. As indicated by the gauge, CO2 operation tops at 1,000 PSI. It took on the average forty five shots for a charge to drop from 2,000 PSI to 1,000 PSI. Velocity drop after a pump fill, associated with lower pressure, began to gradually show below 1,250 PSI, but pressure can fall just below 1,000 PSI before charging is required for proper operation.

 

A valve meters propellant air volume, so there is no direct correlation between pressure and pellet velocity, which means more uniform shot to shot performance. A hammer spring actuates the gun’s striker with uniform force. Stored pressure against the other side of the valve varies. The higher the stored pressure, the more limited the striker’s travel. As pressure declines, striker travel increases. As a result, the valve meters uniform volumes of propellant by adjusting its response to the striker. Recorded over a chronograph, the progression of velocity decline looks like this:

 

I’d attribute the first four or five shots to the absence of break-in leading and subsequent increase in friction as they are notably higher than the rest of the population and this higher velocity did not repeat in subsequent sets of collected data.

 

Let’s define velocity decline as the point where no shot’s velocity is significantly higher than any preceding shots. That point was reached at shot #23, however, the decline remained gradual and the rifle remained fully operational through shot #45. Small game or pest hunting might benefit from recharging the gun at thirty shots to assure maximum power but, for target practice and plinking, shooting until pressure drops below 1,000 PSI is OK.

 

Construction

 

The Benjamin Discovery’s receiver is steel and the bolt actuates not unlike a .22 rimfire rifle; lifted and pulled reward to cock the trigger, pushed forward, down and locked to chamber a pellet. Unlike a spring – piston air rifle where a pellet needs to be in place to dampen the force of its spring loaded piston, the Discovery can be degassed by dry firing.

 

Lots of products look good on the outside, few look as good when the stock is removed. I believe this one in one of the few. Top left, the quick disconnect coupling, as well as all other hardware that hasn’t been nicely blues is plated, cadmium or nickel, I’d guess. The hardwood stock may not be walnut, but it is cleanly finished and moisture sealed inside and out.

 

 

 

The gun comes apart with removal of the detent spring retained cross bolt safety and one 1/4″ x20 screw that passes through the stock and into an oversize stock lug that is anchored to the gun’s receiver.  The fiber filled poly trigger guard, case and cover form good protection for all of the piece parts it contains. Nicely integrated and well thought out design elements. I do not know the gun’s service history, but I would think the Discovery has a good record.

 

I’m at the age of needing good sights or bigger targets…

 

The Benjamin Discovery rifle is supplied with quality fiber optic sights. The rear is fully adjustable for elevation and windage, adjustment stays put once it is set. The sights form a three dot sight picture that is easy to see against bright or shadowed backdrops and they are quick to get on target.

Not a lot of fiddling is required to keep on target with this sight set as shifts in point of impact over the gun’s operating pressure range, or pellet weight range from 4.7 grains to 10.5 grains, are minimal. Groups shift a maximum of 3/4″ as a result of those changes.

I did shoot a few 25 yard groups with open sights. It was nice to see the light pipe diameter was kept to 0.065; plenty of illumination and contrast, but not so large as to obscure a target within legitimate striking distance.

Crosman’s CenterPoint’s Adventure Class 2-7x32mm scope

The CenterPoint Hunting and Outdoors division of Crosman markets a number of shooting accessories, including a range of rifle scopes that would be classify as low to moderate in price; $31 – $200. The scope shown below is manufacturers in China, as is the case with many scope brands these days, and carries an MSRP of $89.99. It is recommended for rifle, shotgun and muzzle loading hunting applications. Because the Benjamin Discovery is not a break barrel, spring piston design, there is no forward recoil in advance of rearward recoil to warrant special air rifle consideration when purchasing a scope.

I can’t speak for lens coatings, shock or fog resistance, or method of purging or filling as these details are not provided in product literature or on the CenterPoint site. However, the scope is of one piece tube construction, it is marked as “Torture tested with a .416 Rigby” and it carries a limited lifetime, original owner warranty. The last point, I believe, tells us what is important, the manufacturer stands behind the product.

Since customers will shoot a variety of pellet types through their rifles, I do shoot other than same brand ammo in my Winchester and Remington firearms, I thought I would try a handful of brands to see how much performance varied. Of course none proved a problem, but performance did vary.