by B.B. Pelletier

Part 1
Part 2
Part 3

Crosman’s new MAR177 upper is big news! This view shows the front sight properly oriented.

Today is the first accuracy test day for the Crosman MAR177 upper, so let’s see how this baby shoots. Blog reader Darth Cossack pointed out that I had mounted the front sight backwards in the last report, so I fixed that for today’s photo. It wouldn’t have mattered from a shooting standpoint, but we do want the gun to look right.

On this AR-15, both the front sight and the rear sight adjust for elevation, while the rear sight also adjusts for windage. The front sight requires a sight adjustment tool that I don’t have and didn’t see packed with the upper. You can also use the point of a 5.56mm military round, which I have an abundance of, but doing it that way is very laborious. I’m hoping the rear sight adjustments will take care of everything that’s needed.

And one more time for those who didn’t read it — the MAR177 is purpose-built for the new sport of National Match Air Rifle (NMAR). NMAR can be shot with traditional 10-meter rifles (using the CMP classifications of Precision and Sporter) and the course is three positions — standing, kneeling and prone. You can continue to use your shooting glove, sling and shooting jacket for this sport, as well. Shooting trousers are not permitted.

The benefit of the AR-15 type rifle that the MAR177 is a part of is that it helps shooters transition over to National Match highpower shooting, because the lower that includes the trigger can be the same for both rifles. And from a competitive standpoint, the MAR177 is very affordable. The only other AR-type air rifle that’s suitable for this sport is made by Anschütz and sells for $1,850.

It cost me $450 to build my lower receiver, and half of that was the National Match trigger. If I wanted to build a lower on a budget, I could do it for under $200 by careful shopping. And I just saw a complete lower advertised in a local sale for $250. But the trigger would then be single-stage and heavier, though there are ways to gunsmith the pull weight down to the legal range of 4.5-5.0 lbs. And when I say the legal range, I refer to high-power competition, only. An air rifle has no trigger-pull limit, because Precision-class target rifles, which are the Olympic target air rifles, are permitted to compete in NMAR.

Why did Crosman make the MAR177 upper for a firearm lower?
This question is being asked by many airgunners. Why would Crosman knowingly make their upper to fit a lower that then classifies the whole rifle as a firearm under federal law? The answer lies in the tens of millions of AR rifles now in the hands of shooters and the extreme popularity of the model. Crosman is building for a market that is more than a hundred times larger than the current active airgun market in the U.S. Even if only a few percent of those owners decide to buy a MAR177, they represent more than all the active airgunners in the United States at this time.

But Crosman isn’t blind to the potential for sales of an MAR that’s not classified as a firearm. I have no doubt they’re working hard on a lower that will accept a modified MAR upper that will not be classified as a firearm. But these things take time. I would expect such a project to be on the fast track right now, but how long it might take before we see it is unclear.

The difficulties are enormous!
You probably think the MAR was easy to develop. After all — every AR is the same (they’re all held to certain specs), so don’t they just have to develop a gun for one lower that will automatically work on all the rest? Actually, no. When your upper has to interface with all the lowers on the market and all possible combinations of triggers in those lowers, there are bound to be some problems. Crosman did their due diligence in designing a universal upper, but there are bound to be some combinations of lower receivers and triggers that experience temporary problems. That would be true for any company designing any new AR-15 upper from scratch.

As I mentioned in Part 2, my Rock River lower and National Match trigger worked fine from the first moment I assembled the rifle, so every new owner can expect success, but there are bound to be some hiccups. There are synthetic lower receivers on the market that are being sold on a price basis that are known to have interchangeability issues with firearm uppers, and this is going to carry over to the MAR177 as well.

I’m not going to list those brands here, but if you do a search for AR-15 lower receiver problems, you’ll come up with a good list of what to avoid. The problems are both the lower receivers, themselves, and the separate parts kits to complete them. People are buying these receivers and parts based on price, alone, and they’re running into problems when one brand of lower won’t accept another company’s parts kit and then work with those three other uppers.

Somebody asked me why I chose a Rock River lower receiver and a Rock River parts kit, and I’m telling you why. There are other brands that are just as good, and a few that are even perhaps better, such as the Giessele National Match trigger that one of our readers mentioned, but you have to be aware of the fact that not all AR-15 uppers fit all AR-15 lowers.

What I’m testing
One final comment I want to make. Building a gun like this is full of decisions. You are free to choose whatever appeals to you; but once you choose, your path is determined by the decisions you make. As I said before, there’s no trigger-pull weight restriction in the NMAR class for air rifle shooting, but if I were to want to use the same lower in a match with a firearm, I would be restricted to a weight range for the trigger release and also the style of pistol grip. While I’ll probably never compete in a high-power military-style match, I wanted to shoot a gun that would qualify. It was a choice I made, and one that you do not have to follow. But that choice led me to a certain level of performance in the rifle I am now about to test.

I’m also shooting the military-style post front sight. An aperture front would allow more aiming precision; but if you want to use the MAR as a training tool for your high-power competition rifle, you’ll stick with the sights that come on the upper.

The test
I shot 5 shots per group off a rest at 10 meters with each pellet I tested. Since there’s going to be more testing with this gun, I didn’t try to test all the pellets I have, but I did try eight different ones.

Sighting in was done with the Crosman Premier Super Match target pellets that Crosman packed with my test gun. And they were astonishingly good! The group fired for record measured 0.144 inches between centers. That’s in the range for CMP (Civilian Marksmanship Program) and NRA Sporter class 10-meter rifles that have much lighter triggers and aperture front sights. I was impressed.

Crosman Premier Super Match pellets are great in the MAR177. Five shots went into a 0.144-inch group between centers at 10 meters.

Loading is not perfect
I used the single-shot tray for all this testing. This is the same tray that the Benjamin Marauder uses, and there’s a small gap just before the breech of the barrel. If you try to load the pellet tentatively, the head drops into the gap and binds. If you slam the bolt home too fast, the pellet jumps up in front and also jams. It takes a while to get the right closing speed so the pellet feeds smoothly. Not all pellets jam this way, but a couple are particularly bad. You’ll have to try it for yourself if you use the tray. I was able to get the feed right for every pellet I shot, so it’s not a problem — you just have to spend some time to learn the peculiarities of the gun with the ammo you choose.

You can see the gap at the front of the single-shot loading tray. You have to learn how fast to load pellets to get wadcutters past that gap.

Number two
The second-best pellet in the test was the Gamo Match. While the group they made looks large, it’s so round that it doesn’t take up that much room. In reality, this probably means they’re not really second best, but I may have made a small aiming error with one of the other pellets. However, it’s surprising that such an inexpensive pellet is also this capable.

Five Gamo Match pellets made this 0.136-inch group. Second best of the test, though it appears open.

Best group
RWS R10 7.7-grain pellets that are no longer available gave the best results, with a group size of just 0.106 inches between centers. I shot them early in the test and was probably more rested than I was later, so my eyes were working at their best.

RWS R10 7.7-grain pellets made this five-shot group measuring 0.106 inches. It was the best of this test.

The other pellets
Besides these three, I tried five other target pellets. They were all very equal to the Crosman Super Match, and the largest group fired during the test was 0.162 inches with RWS Hobbys.

H&N Finale Match Rifle

H&N Finale Match Pistol

RWS R10 Match Pistol pellet

7-grain RWS Hobby

JSB S100 Match

One test like this is not enough to determine the most accurate pellet. If I were to do the same test again, the results would no doubt change. Lots more testing is needed to find that one best pellet for this competition air rifle. However, one test was sufficient to prove that the MAR177 has everything going for it. It’s accurate, easy to use and conserves air like a free diver. It mates to an AR lower perfectly to become the best possible training system for AR shooters.

I have more plans for this rifle. Next, I plan to mount a scope and test the rifle with accurate domed pellets at 25 yards. I believe the MAR177 has more to show us.