Gun Review: Crosman MAR177 AR Upper

Remember the great ammo shortage of 2010? Thanks to a perfect storm of economic, political and psychological factors, prices shot through the roof (not literally). Millions of budget-conscious shooters discovered the economic joys of firing low-cost .22 caliber ammunition—especially when it flew out of the barrel of a gun that looked and worked like its bigger caliber cousin. Even mucho macho AR-15 lovers took to .22-caliber ARs and, better yet, rimfire-firing conversions for their existing weapon system. The trend is far from over. How’s this then: a .17 caliber PCP (Pre-Charged Pneumatic) air gun upper receiver for your AR-15. Enter the Crosman MAR177 AR Upper. It converts your AR-15 into a bolt-action—make that pull-action—air rifle . . .

Note: this ain’t your daddy’s Red Ryder. The MAR177’s 21-inch, rifled and choked, free floating Lothar Walther barrel weighs seven pounds, six ounces. The gun comes with a ten-round rotary clip [their words] that holds 120 shots per fill. The MAR177’s fitted with a standard Picatinny rail that will (of course) accomodate anything from red dots to serious scopes. As you’d expect at the price, it’s a serious piece of kit.

We’re talking about a PCP .177 caliber National Match Air Rifle competition grade rifle, straight out of the box. You can also use the MAR177 shooters as a full-on training rifle for National High Power Competition. Self-defense shooters looking to shoot-and-scoot can slap on a sling and do their thing in the comfort and privacy of their own backyard or, yes, house (observing appropriate safety protocol and neighbor notification).

And let’s not forget the MAR’s trigger and sight system are perfect for younger shooters who might not be comfortable with the standard AR-15’s recoil or muzzle blast. A young man eager to explore his militaristic fantasies might consider the MAR117 The Mother of All Air Rifles. What could possibly go wrong?

If you wanted to put an eye out with that thing, an MAR177-equipped AR shooting match grade pellets (yes there are such things) offers stunning accuracy at 20 yards. Unlike some of the plastic fantastic .22 AR’s frustrating owners with ammo sensitivity, the Crosman pellet gun is as reliable as a teenager’s fascination with’s Hot Girls in the Middle of Nowhere feature.

With or without comely companionship, an MAR177 shooter can plink in the middle of nowhere without worrying about disturbing the horses. Dandelions, however, should be very, very nervous. It’s almost as easy to shoot the heads off the weeds at 15 yards as it is to cluster holes on scaled NRA targets at 20.

20 yards, offhand

A solid test of how well this rifle imparts good habits and solid fundamentals on an individual: shooting an Appleseed Army Qualification Target. The Appleseed AQT consists of one large bust silhouette designed to simulate 100 yard shooting for its first stage, two medium busts simulating 200 yards for its second, and three small busts simulating 400 yards respectively. The shooter engages the first stage while standing, the second while sitting, and the third while prone.

I’ve managed to shoot the mythical rifleman score and earn my patch about a year ago using a SIG SAUER 556 Patrol rifle with 50mm 9x Leupold glass. Truth be told, I felt like I’d cheated. This time around I used a BCM 20” upper on a Bushmaster lower with a fixed A2 stock using only iron sights. I modified the course of fire to consist of only 30 rounds. Here’s my control group(ing).

Score:145/200: Sharpshooter

I set the bar fairly high, having shot sharpshooter on my first attempt. I set up the exact same course of fire in my backyard at a distance of 25 yards (the AQT is scaled for that distance). I removed the existing BCM upper and replaced it with Crosman’s MAR177.

The MAR177 assembles like a standard upper with one exception: you use a 3/16” Allen key wrench to loosen a screw located under the carry handle sight to relieve pressure on the assembly pins. Once the upper is installed, simply tighten the small set screw and reinstall the carry handle. It’s easy but inconvenient; you have to check zero every time you convert the rifle back to original configuration.

After popping the MAR177 upper on my Bushmaster, I shot the same course of fire. After repeating this 20 times (a total of 600 rounds expended) with the MAR177 upper, I replaced the airgun upper with the BCM 20” 5.56 upper.

Score:174/200: Marksman(Rifleman)

The additional training with the air rifle upper improved my score by 14.5 percent. That sort of improvement could make or break a score in competition, and mean the difference between being in the winner’s circle or not. I’m an experienced shooter. A noob with proper instruction shooting the Crosman MAR177 could see a vast improvement in their marksmanship.

If you’re the kind of shooter who only visits the range to sight in your new deer rifle or blast off a 100 rounds once a month, the MAR177 Upper is not for you. A gun that goes ffft not bang won’t light your synapses. If you’re a competitor, aspiring marksman, self-defense shooter or someone who just likes to goof around with cool-looking guns (observing proper safety procedures), the MAR177 is a must-have accessory.

UPDATE: Crosman has informed me that the set screw located under the rear sight does not need to be adjusted in order to maintain zero.


  • Model Number     MAR177
  • Velocity                  Up to 600 fps
  • Weight                    7 lb. 6 oz.
  • Length                    28.5
  • Mechanism            Repeater
  • Power Source        PCP
  • Caliber                    .177
  • Capacity                 10-Shot Rotary Clip
  • Barrel                     21 in
  • Front Sight            Removable post with adjustment
  • Rear Sight             Carry handle adjustable flip peep
  • Optics Rail            Picatinny
  • Safety                     Crossbolt
  • Material                 Synthetic
  • MSRP                     $650

Ratings (out of five stars):

Style  * * * *
I’m a big fan of the A3/A4 style AR-15’s and this looks awfully close. I didn’t like the odd hand guard but it gets bonus points for the weighted faux magazine.

Ergonomics  * * * * *
IMHO the AR-15 is the definition of ergonomic comfort. It will fit most users like a glove.

Reliability  * * * * *
The MAR177 has digested 700 rounds of Gamo match grade pellets so far without so much as a hiccup.

Customization  * * * * *
Unparalleled accessory support, there might not be enough room for a BUIS and an RDS, but on a pellet gun there is little to reason for a BUIS.

Overall Rating * * * * *
Even at $650 (MSRP), the MAR177 a bargain. It’s accurate, comfortable, and familiar; an ideal training platform.