Crosman’s new M4-177 multi-pump air rifle: Part 2
by B.B. Pelletier
Before we begin, I want to wish a Happy Thanksgiving to all my U.S. readers. I certainly have a lot to be thankful for, and I hope all of you do, as well. Now, on to the report.
This Crosman M4-177 multi-pump air rifle has proven to be one of the most interesting new air rifles of the season; and as a result, I’m looking at it a little more thoroughly. Today is the day we test velocity, and I have a couple other interesting things to share. One I’ll share right now…I bought the test gun. This is a neat rifle, plus this is a future collectible because Crosman will change the name stamped on the gun (from M417 to M4-177) by January 2012.
It’s a multi-pump
As a multi-pump pneumatic, the M4 allows the shooter to pump a maximum of 10 strokes, with the power varying with every new stroke. You probably don’t want to pump less than three times because the power is so low you risk getting a pellet stuck in the barrel; but from three to ten pumps, it gives you the ability to vary the power of the gun according to the situation.
How can you shoot BBs in a rifled bore?
The first question I’ll address is the fact that you can shoot both BBs and lead pellets in this rifle. It has a rifled steel barrel that will tolerate steel BBs without undue wear. Like you, I wondered what the rifling for such a combination gun must look like, so I took a reverse impression of the bore by pushing a Beeman Kodiak pellet from muzzle to breech. The rifling was engraved on the pellet, giving us a look at the bore in reverse.
Notice how much lead has smeared to the back of the lands and sticks out like a small tail as an extrusion at the rear of each channel. This is what barrel maker Harry Pope said was ruinous to accuracy, because it’s influenced by the expanding gasses at the instant the bullet leaves the muzzle. In other words, it’s the equivalent of a poor crown.
Now we know what the inside of the barrel looks like. Does Crosman harden their barrels to prevent wear from the steel BBs? I don’t know, but I would presume that the rifling button will work-harden the steel to a certain extent, and maybe that’s all it takes.
Shooting BBs in the M4
When you shoot the M4, you can choose between BBs and pellets but it’s a choice you must make. If you leave the BB magazine loaded and also shoot pellets, I would imagine there could be a double-feed problem. The BBs are picked up by the magnetic tip of the bolt, while the pellets are simply shoved out of the clip and into the breech when the bolt is shoved forward.
When I refer to the BB magazine, I do not mean the 350-shot BB reservoir. You can leave that full all the time and shoot lead pellets without a problem. I’m referring to the visible BB magazine that can be seen on the left side of the gun.
The visible BB magazine on the left side of the gun is filled from the internal 350-shot BB reservoir. The small switch at the right of this photo controls this magazine. Here it’s shown in the open position, so the magazine can be filled by holding the muzzle down and shaking the gun with a twisting motion. After the magazine is filled, push the switch to the rear to retain the BBs.
The instruction manual says to watch the tip of the bolt when feeding BBs into the breech. I found that to be impossible, because the 5-shot pellet clip blocks the view, and it must be in place to feed BBs. But you can watch the BBs move through the visible magazine window shown in the photo above and know for certain that a BB has been fed. Once I figured this out, there were no difficulties and feeding was reliable.
Velocity with BBs
I started with Daisy zinc-plated BBs because I’ve noted in past reports they’re the most uniform and usually give the highest velocity and the best accuracy. I decided to test the gun on five pump strokes and again on ten. That should give us an idea of what the gun can do.
On five pump strokes, the BB averaged 460 f.p.s., but the velocity spread was large. From a low of 451 f.p.s to a high of 483 f.p.s., the total spread was 32 f.p.s. Normally, I expect to see a 6-10 foot-second spread when shooting with the same number of pump strokes. However, I did see that the more I shot the gun the faster it went, up to a point. I think the pump cup needed to be warmed up through repeated use, even though I shot in 70 degrees F (21 degrees C) temperature, so it wasn’t too cold for the gun. The pump cup just needed to be flexed a bit to warm it and get it sealing all the way.
On ten pump strokes, the gun gave an average of 579 f.p.s. with the same BB. This time the spread went from 566 to 588 f.p.s., so it was still a 22 foot-second spread. Perhaps the hardness (durometer) of the pump cup material is causing such a large spread. That would probably make it a longer-lasting material, so there’s a tradeoff.
Okay, I guess it’s not fair to test a Crosman gun and not use their BBs, so I also tested some Copperhead BBs. On five pumps, the rifle averaged 465 f.p.s. with a spread from 459 to 472. That’s only 13 f.p.s., which is much tighter than the Daisy BBs.
On ten pumps, the gun averaged 581 f.p.s., so it’s also a little bit faster than with Daisy BBs. The spread went from a low of 574 to a high of 592 f.p.s., so a total of 18 f.p.s. The bottom line is that Crosman Copperhead BBs are more consistent in the M4. I guess I’ll have to try both in the accuracy test.
Pumping not that easy
I said in Part 1 that the M4 is easier to pump because the stroke is short. Well, after today’s test, I have to change that. After you pass five strokes, the effort required to pump increases; and by the end of the session, my left hand was hurting from the pump handle. Also, the gun makes quite a racket with every pump stroke because the handle slaps down hard when the stroke is finished.
Velocity with pellets
I tried only a single pellet in the rifle. I tried it on five pump strokes and on ten. The pellet I used was the Crosman Premier Super Match, which is a wadcutter target pellet that’s appropriate to a rifle in this power range. On five pumps, the pellet averaged 429 f.p.s. and ranged from 424 to 433 f.p.s. The velocity spread is much tighter when the projectile fits the bore better.
On high power the same pellet averaged 529 f.p.s. with a low of 508 and a high of 545 f.p.s. That’s a big spread for a pellet in a multi-pump rifle, so I don’t know what is going on.
What about lead balls?
I figured someone would ask about shooting round lead balls out of this rifle so I tried it. First, there was difficulty finding a ball that worked. Since lead balls aren’t magnetic, they won’t feed properly through the BB feeding mechanism, so they have to be treated like pellets and fed from the clip. That eliminates all round balls smaller than a .177 pellet because they won’t stay in the clip long enough to feed into the barrel. The only round ball that worked somewhat was a Beeman Perfect Round, which is no longer made, but is similar to the H&N round ball. These measured 0.176 inches, which is close enough that they stuck in the pellet clip — sort of. When I tried shooting them, the two that were outside the receiver fell out of the clip on the first shot, so they’re not really large enough to use in this gun.
On five pumps, the one shot I fired went 407 f.p.s.; and on ten pumps, the other two shots went 502 and 519 f.p.s. I do not recommend this ammunition in this airgun.
Impressions thus far
Today, I got past the appearance and had a good look at the functioning of the rifle. The fact that the clip has to be indexed by hand for every shot slows you down more than you might imagine. Like I said in the first report, making a multi-pump a repeater sort of misses the mark. The time that it takes to get ready for the next shot negates any speed the repeating mechanism offers.
My test gun is shooting slower than the advertised top velocity of 625 f.p.s. for this rifle. It’s close, at 581 with Copperhead BBs, but not close enough. Maybe the rifle needs to break in, or perhaps the 625 f.p.s. is what a lone maximum shot could potentially be.