Dropping your trusty AR down to .177 caliber in one change of the upper

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The neat thing about the AR-15 series rifles is the ability to, with the removal of a pin, change out the entire upper receiver to accommodate your flavor of the minute. This allows the same platform to move from caliber to caliber, short CQB style uppers to long, heavy match-style varmint set ups-- the sky is the limit. Well, one conversion that can help with your training needs while conserving your stock of 5.56mm is an air rifle conversion.

Say what?

We didn't stutter. A couple years ago Crosman, one of the longest running names in airguns, and Pilkguns, a big name in the world of Olympic competition-grade airguns, teamed up to make a modular AR-compatible upper that would both perform and simulate the 'real thing' as much as possible.



The upper, termed the MAR177, simply replaces any AR-style upper receiver and can marry to a standard lower (sans magazine). Once installed, the PCP (Pre-Charged Pneumatic) .177-caliber pellet rifle upper is good to go as long as you have air in the tank and pellets on tap. The surface controls (including the charging handle) are laid out correctly to a standard AR-15. The carrying handle holds a correct and adjustable National Match 1/4-inch sights. Should you want to add optics, the handle comes off to allow mounting of anything you want on a standard Picatinny rail.


According to Crosman Product Manager, Terry Neumaster, "The Crosman MAR177 PCP Rifle is designed to support match air rifle competitors, using the traditional service rifle of National Match series competitions. To better serve the requirements of elite competitors, we've partnered with two-time, National NRA High Power Rifle Champion, Dennis DeMille of Creedmoor Sports Inc.," he said.

Best yet, you are using your own lower, which means every shot fired is with your trigger group. When your sights or optics are mirrored on the MAR177 upper, you are simulating everything about your gun except the recoil and the price of the rounds fired.


The gun is powered by a standard air reservoir capable of firing about 120 shots and can be refilled by a hand pump. It uses the same 10-shot and single-shot adapter magazine as the Benjamin Marauder series of guns. In fact, since Crosman (who now owns Benjamin) developed the MAR177, many features of their upper-line PCP series rifles (read: reservoir) seem to be the same.

"Using the magazine, 10 RWS R10 7.7-grain pellets (an obsolete weight for the R10) grouped in 0.484 inches at 25 yards. That's great performance." Photo by Pyramydair

Airgun Reporter Episode #93 - Specifically on the Crosman/Pilkgun MAR .177 AR15 upper, using a Panther Arms lower. Air Gun Reporter considered it 'backyard friendly' in terms of noise propagation, and verified the manufacturer's specs as far as accuracy, capacity, and operation.

Velocity Up to 600 fps
Weight 7 lb. 6 oz.
Length 28.5 in
Mechanism Bolt Action
Power Source PCP
Caliber. 177
Ammunition Pellets
Capacity 10 Shot Magazine
Barrel 21 in
Front Sight Removable post with adjustment
Rear Sight Carry handle adjustable flip peep
Optics Rail Picatinny


Now don't get us wrong, there are some drawbacks on this upper. With its 21-inch Walther Lothar match grade barrel, the upper is heavy (7-pounds) which gives your gun a bit of extra heft. In addition, it's on the long side, which counterbalances any move and shoot training that you intend to do with the rifle while set up as an air gun.

Then there is the power curve. As far as airguns go, the MAR177 is petty low-powered at about 600 fps. This makes it a decent target gun but if intending to hunt small game or pests with the set-up, it is only on the marginal side of capability. However it is laser accurate, capable of putting 10-shot groups made from 10-meters (32-feet) inside less than a half-inch MOA, which is a counterpoint to this argument.

Then there is the price. We checked around and around and around and around once again and the best (only!) price we could find on these uppers was $600. If you want an airgun, there are much better, less expensive options out there for this. If you want a cheap upper for your AR that fires inexpensive ammunition, you can get a dedicated .22LR upper for less-- but is .22LR really that inexpensive anymore?

On the brightside with the upper being so self-contained, you can build an inexpensive lower (polymer anyone?) to set the gun up as a dedicated all-up airgun for about $800.

Also the legality of this is that any working AR-lower, when attached to this airgun upper, is still a firearm- and has to be treated as such.

Nevertheless, these conversions are out there and are a valid option for introducing young or inexperienced shooters to AR platforms with a minimum of stress as well as providing a source for truly inexpensive practice. The $600 price could be paid for in just two cases of saved 5.56mm ammunition while the trigger time is yours to keep.

After all, we haven't seen anyone starting to horde .177 lead pellets.


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May 9, 2014  •  04:49 PM
Haha! I have over 25k pellets (in 4 calibers) from the early to mid 90's, when I became obsessed with air rifles.
Let the hoarding begin!!
I have a few domestic rifles, but back then, the real quality was in the European guns. I've got a few...
May 9, 2014  •  05:33 PM
If I were to carry this around in my neighbor hood, the cops would have a feld day, Then say it was thought to be an all out weapon
August 13, 2016  •  02:10 AM
your right about the .177 pellet for target is better than a .22 caliber pellet as far as hunting the .177 can go through a rodent so fast and not take it out would cruel , so to hunt small animals .22 and target .177