December 03, 2019
By Tom Gaylord
Stoeger’s new S4000E breakbarrel spring-piston air rifle combo is a moderately priced breakbarrel gas spring rifle that comes in both .177 and .22 calibers. It has several things I have never seen before, including a silencer that has a large air expansion chamber beneath the barrel.
The S4000E is rated to 1,200 fps in .177 caliber with alloy pellets and 1,000 fps with lead. In .22 caliber the ratings are 1,000 fps with alloy and 800 fps with lead. I asked for a .22 caliber to test because that is a reasonable power level for a spring-piston air rifle. It actually has a good chance to be accurate, compared to all those 1,400 fps mega-magnums that will spray lead everywhere as they slap you silly.
The rifle comes you with a 4x32 scope and mounts to augment the adjustable open sights. The scope is not mounted on the rifle, but it is in the rings, so all that’s needed is to attach the rings to the top of the rifle. You can scope it in one minute! I will test both the open sights and the scope separately.
Before I describe the rifle let me tell you about a couple of its unique features. I’ll start with the Multi-Grip System (MGS). The stock is 100 percent synthetic, and has two panels on either side of the pistol grip and two more on either side of the forearm, at the swell where your off hand goes. The black panels that come on the rifle from the factory are checkered with coarse diamonds, but they can be swapped with orange panels that have finer stippling or blue panels with the smoothest stippling of all.
I hoped that one of the panel sets would have a Wundhammer palm swell for the pistol grip, but no such luck. All panels share the same slim profile. I tried all three and definitely prefer the coarse diamonds of the original black panels that Stoeger calls their Pro Adaptive Checkering.
Another unique feature is the rifle gives you a choice of two different fiberoptic front sight tubes. That’s something I’ve never seen before. The front sight comes with a red tube installed and a much brighter orange/red tube as a replacement. The red tube seems dark to my eyes and when I use the open sights I will probably shoot with it for greater precision, as it will appear to me as a plain black post.
The rear sight adjusts for both windage and elevation. The manual tells you which way to turn the knobs to move the sight, which is good because neither set of adjustments has any reference markings. However, in yet another first, there is an adjustment knob on each side of the rear sight for windage, helping make the rifle ambidextrous.
The final unique feature I examined is the silencer. It’s baffled and the baffles direct the pressurized air down into a large expansion chamber located below the barrel. This quiets the discharge at the muzzle, however the shooter will hear the powerplant sound through the bones in their face that’s pressed against the stock. To the shooter only the rifle will sound louder. I have to comment that while it is a quieter rifle for its power, it’s probably still a bit loud for the smaller suburban back yard.
The S4000E is a breakbarrel rifle powered by a gas piston. It weighs 7.65 lbs., which is light for the power that’s produced. My neighbor, Denny, who is holding the rifle in the opening photo was surprised by how light and perfect the rifle feels. It looks big but holds small.
It’s physically a large rifle, at 44.125-inches long with a pull of 14.5 inches. The pistol grip and trigger blade are far enough apart to favor a larger hand.
The stock is 100 percent synthetic with a Monte Carlo comb and a raised cheekpiece on both sides for ambidexterity. The stock is nicely sculpted to fit both hands, with the forearm swell perfectly positioned for my off hand. When I raise the rifle up to my cheek it aligns quickly.
The synthetic material of the stock is smooth in most places, with the coarse checkering I mentioned earlier where the hands touch. The synthetic material is hard at all places except at the buttpad, where it is a soft grippy rubber. The feeling of all these parts makes this an easy rifle to hold offhand.
Gas spring/gas piston breakbarrel rifles used to be extremely hard to cock. Just 10 years ago 50 pounds of effort to cock was normal and I have measured some that went up to 75 pounds. But airgun designers have discovered that they can put less gas pressure in the spring or piston unit and still get plenty of power as long as the piston’s stroke is long. I think they learned that from the automobile industry! The S4000E’s piston stroke is quite long, as can be seen when the barrel is broken open. The actual rifled barrel is only 14 inches long, but the barrel shroud takes it out several more inches for both leverage as well as silencing. When the rifle has a long piston stroke the cocking effort doesn’t need to be that hard.
The two-stage trigger breaks at an average 4 lbs. 6 oz. Stage one stops at 1 lb. 5 oz. Stage two does have some travel but not a lot of creep. Travel means you can feel the trigger blade move; creep is an uneven starting and stopping throughout the trigger pull. However, there is a point in the second stage of the pull where the trigger blade moves back a lot with no increase in effort.
The trigger adjustment affects the length of the stage-two pull. Stage two isn’t supposed to have a length in my book; it’s supposed to break like a glass rod. Well, this trigger doesn’t. Stage two acts more like a single-stage trigger that moves before it breaks. I tried the adjustment but didn’t accomplish much. However, it’s not bad. The trigger seems quite useable to me as it came from the box. I will have more to say after the accuracy test, because that is when I feel the trigger the most.
The safety comes on automatically each time the rifle is cocked and is very easy to take off because of where it is located. The safety is a button that’s centered on the spring tube at the top of the pistol grip, so once again Stoeger thought of ambidexterity.
There is an anti-beartrap mechanism in the system that prevents the rifle from being uncocked except by firing. The mechanism is there to prevent the barrel from closing suddenly on your fingers during loading. Such accidents have amputated parts of fingers in the past, so anti-beartrap devices were created. Now that you know the function, the name is very revealing.
As good as they are, though, we do not leave safety entirely to mechanical devices. They can always fail. So, whenever we load a breakbarrel air rifle we hold onto the end of the barrel just as we did to cock the gun. If the gun were to fire, the barrel would be restrained long enough to get our fingers out of the way.
What this means is that if you cock the rifle, you must put a pellet in and fire it to uncock it again. There is no way around this. It is not recommended that you shoot the rifle without a pellet in the breech, because there is no way for the piston to slow down before hitting the end of the compression chamber. The pellet in the breech seals the air channel, allowing pressure to build that both sends the pellet downrange and also slows the piston to a near stop.
One of the big benefits of gas springs and pistons is the compressed gas inside them never takes a set like coiled steel mainsprings do. You can leave the rifle cocked for hours with no degradation in power. That’s a real plus for hunters. Don’t do that indiscriminately, though, because a loaded and cocked rifle of this power is extremely dangerous. And that leads to the next discussion — how powerful is the S4000E?
I selected the .22 to test, and I’m glad I did. According to the sales literature with light lead pellets it gets around 800 fps, and 1,000 fps with alloy pellets that are even lighter. That is right where I want to be with a spring piston rifle — especially one with a gas spring. I’m counting on that long stroke to make the cocking lighter, and I’ll test for that.
First to be tested were RWS Hobby pellets. These are 11.9-grain wadcutter pellets that are one of the lightest pure lead pellets on the market. They chambered very snugly in the breech of the S4000E and averaged 801 fps, so Stoeger’s velocity claim of 800 fps, with lead pellets is upheld.
The variation went from a low of 781 to a high of 838 fps. That’s a spread of 57 fps which is high, but the rifle is brand new. After it settles in the spread will be tighter.
At the average velocity the Hobby generates 16.96 foot-pounds of energy. That’s a nice place to be for accuracy and consistency with a spring-piston air rifle. Now let’s look at an alloy pellet.
For the alloy pellet I shot some .22-caliber Gamo Raptors that are no longer being sold. They weigh 9.9 grains. I used them because I don’t have a lot of alloy .22 caliber pellets on hand. While they typically give the highest velocity, their accuracy usually leaves a lot to be desired.
Most Raptors fit the breech very tight, but a few fell in with no resistance. That tells me they are not sized consistently, which will have a negative impact on accuracy. The average velocity was 943 fps with a spread that went from 892 to 960 fps. That’s a whopping 68 fps and both the slowest and fastest pellets were loose in the breech. At the average velocity the Raptor generated 19.55 foot-pounds. We expect the most energy from the lightest pellet in a spring-piston airgun, and this seems to follow the norm.
Next to be tested was a middleweight pellet. In .22 caliber the middle ranges around 14–16 grains. At 14.5 grains, the RWS Superdome is a pellet I would expect to shoot in this rifle. It might be among the more accurate pellets — or at least that’s what I’m hoping. I say that because Superdome pellets have a proven history of accuracy in .22 caliber.
The Superdome pellet chambered about perfectly in the S4000E — snug but by no means tight. It averaged 732 fps with a spread that went from 722 to a high of 738 fps. That’s a spread of just 16 fps, and given the large spreads of the first two pellets, it’s an indication that this pellet might be right for the powerplant. At the average velocity Superdomes produced 17.02 foot-pounds of energy at the muzzle.
I have tested the lighter pellets and one middleweight, now let’s see what a heavier pellet will do. In .22 caliber there are pellets that weigh as much as 34 grains, but given the power potential of this rifle, I wanted to stay with a pellet of around 20 grains.
The Beeman Kodiak weighs 21.14-grains and also has a long history of accuracy in both .177 and .22 calibers. Kodiaks are no longer made, but they are identical to H&N Baracudas — a pellet with worldwide distribution. This pellet averaged 602 fps at the muzzle and had a velocity range that went from 598 to 606 fps. That’s just 8 fps. While it isn’t that fast, it certainly is consistent, and consistency usually means accuracy! At the average velocity this heavy dome produced 17.02 foot-pounds of energy. I find that even more proof that this pellet is well-suited to the S4000E powerplant.
This rifle is very calm when it fires — and calm is not a typical thing for gas spring guns! The firing cycle is super-quick — telling you that the rifle has a gas spring, but there is no buzzing and no slap in the face usually accompanies this type of powerplant. The recoil is also quite minimal. It feels like it is performing within its design parameters, which is a very good thing.
I tested the cocking effort, which consists of putting the muzzle on a spring bathroom scale and pressing down until the rifle is cocked. The effort required was 34 lbs. with some stacking or increase after the halfway point of the barrel arc. As mentioned earlier, gas spring rifles used to commonly require 50 pounds of effort to cock, so the S4000E is an advanced design. I’ll have more to say about this when I test the rifle for accuracy because that’s where the effort affects me the most.
Because the barrel comes back as far as it does, there is a point almost at the end of the barrel arc when the cocking effort becomes harder just because of geometry. Your arms reach a point where not as much power is generated. Fortunately you can learn to grab the barrel in such a way that this point is never reached. I used two hands to complete the cocking stroke most of the time, though it was very possible to do it with one if I wanted to.
The barrel detent does requires a little slap to break open, but it’s really nothing much. I tried breaking it with two hands and couldn’t, but the slap is the lightest I have ever felt. Now let’s see what the rifle does downrange.
The S4000E comes as a combo that has a 4x32 scope and mounts included. And the rifle also has adjustable open sights. I will begin the testing with open sights that will be a shakedown to learn as much as I can before I mount the scope. There are a couple things I want to find out from this first test. First, I want to know which pellet(s) the rifle likes. That way I won’t waste any time when the rifle is scoped.
I also want to discover how to best hold the rifle. The S4000E has a gas spring that usually makes rifles hold-sensitive. So I began the test expecting this rifle to be sensitive and I was looking for the best hold to use.
Sighting-in went smoothly. When shooting with open sights I sight-in at 10 meters, because I believe the designers have placed the open sights at the right place to get the rifle on paper. In 40 years of testing I haven’t been wrong yet. With scopes it’s a different story, but as long as the open sights are not damaged they will be on target at 10 meters. Now it was time to start testing pellets.
The First Test
After sight-in I was ready to test. I shot off a sandbag on a bench, using an artillery hold. That’s where I rest the rifle on the open palm of my off hand and hold the stock as lightly as I can. That allows the rifle to recoil as much as it wants, and surprisingly that is a secret to accuracy with any spring-piston air rifle. Hold them like a deer rifle and they spray pellets everywhere. They don’t all need to be held this way but the ones that move a lot in recoil almost always do. And nearly all gas spring guns fall into that category.
I only rest my off hand on the sandbag. In case you aren’t aware, only a few air rifles can be rested directly on a sandbag and still be accurate, and it’s best to start your test thinking the rifle is sensitive to hold.
I shot 5-shot groups because I wanted to test as many pellets as possible. I used the open sights and, while I did adjust them as I went, I wasn’t looking to hit the center of the bullseye. I just wanted the group to be somewhere on the paper target. I was looking for small groups — not high scores.
I tried JSB Hades, a new hollowpoint that has recently come out, Air Arms Falcons, a lighter domed pellet with a good track record and Arms Field pellets — another good domed pellet. Unfortunately all these first groups were too large to consider, but they did teach me something. This rifle shoots each pellet to a different location on the target. It’s so different that until I found the right pellets it didn’t make sense to adjust the open sights. I did discover that holding the rifle on my off hand back by the triggerguard was the correct way to hold the rifle. That set me up for the next discovery — which pellets worked!
The first pellet that made some sense (with the right artillery hold) was the JSB Exact RS dome, five of them went into 1.09-inches at 10 meters, with three of them in just 0.339-inches. An inch for five shots at 10 meters isn’t good, but it was the best I had seen to this point.
The RWS Superdome that I mentioned before was the first good pellet I found for the S4000E. Five pellets went into 0.555-inches at 10 meters. When I saw this I knew the rifle was accurate, because remember that I’m shooting with open sights!
Okay, I’m on a streak now. What about that other good pellet — the Beeman Kodiak that I said is the same as an H&N Baracuda? Well, I switched to H&N pellets for this test. Five H&N Baracuda Match pellets with 5.53mm heads turned out to be the very best at 10 meters. They are the exact same pellets as the obsolete Kodiaks I shot earlier. They are just sold under a different name, and H&N gives us a choice of head sizes where Beeman didn’t. I picked up the tin of 5.53mm heads at random, and look what they did! Five pellets went into 0.438-inches at 10 meters, and that is with open sights. This rifle can shoot!
Remember I said that this rifle is smooth? Well, it really is! When shooting for accuracy this first time I had my face against the stock for 55 shots and can tell you the rifle doesn’t slap — not even a little. It does lunge forward a little, but even that is under control.
How Is The Trigger?
I promised to report more about the trigger after shooting the rifle for accuracy, because that’s where I get the most exposure to it. The second stage on the S4000E has a long travel and it’s easier for me to think of the rifle as having a single stage trigger, because that’s how it acts. I got used to it right away and once I did, and also found the right way to hold the stock, look at the results!
This rifle needs to be held with the artillery hold (stock rested on the open palm of the off hand with a soft grip all around to allow the rifle to recoil as much as it wants to). Most spring-piston air rifles are sensitive to how they are held and this one, being a gas piston, is very sensitive. I tried several different holds during the 10-meter test and also during the much longer 25-yard test that’s coming next. I established beyond a doubt that this rifle wants to rest on my open palm with the heel of my off hand touching the trigger guard. Because the stock is so slim at that spot your hand can’t help but be a little cupped around the stock. As long as you don’t grasp the stock with your fingers it will be fine. Also don’t pull the stock into your shoulder, but you do have to grasp the pistol grip because the trigger is heavy enough to require it.
I cocked the rifle 55 times in the first test and can now report that it’s not that hard. The one thing that’s different is because the barrel comes down so far the rifle becomes a little harder to cock for the final few inches. It gets hard at a place where your arm wants it to ease up. It’s a geometry thing, and I found it easiest to use my other hand to boost the effort. I cocked it one-handed maybe 10–5 times and the rest was where I used the second hand at the end of the stroke. I could have gone on to shoot another 55 shots with ease, doing it that way.
Prepare For 25 Yards
Ten meters is a good place to start testing, but you can’t establish the true accuracy that close to the target. Now, at 25 yards things start to gel. So I backed up to 25 yards and used the same setup as before — rifle rested on my off hand in the artillery hold.
I expected the groups to increase in size, which they did. In fact, my first test at this distance proved disappointing because the best five-shot groups I got were all over one inch between centers. Three pellets would go neatly into a half-inch and then two would land away from them, opening the group considerably. When that happens with a firearm rifle and the ammunition is not suspect, I know that it’s always the hold. But with a pellet rifle is can be a few other things that I addressed.
Loose Stock Screws
One common cause for open groups with spring-piston air rifles is stock screws that are loose. It’s the same thing as a poorly bedded firearm, and we all know what that can do. So I went over the screws and found the two forearm screws were tight but the lone screw in the rear, at the back of the trigger guard, was very loose. That’s the worst screw to be loose because it directly relates to the bedding of the action. When I tightened it the action was pulled down into the stock. No way the rifle could have shot well with that screw loose.
Clean The Barrel
Another trick of the trade is to clean the barrel when the accuracy is off. I use JB Non-Embedding Bore Cleaning Compound on a brass brush that’s mounted to a solid Dewey cleaning rod. The Dewey rod swivels as the brush takes the rifling and a solid steel rod can do less damage to a bore than a segmented rod. A pull-through system will work, but for this procedure I want to scrub back and forth along the length of the bore and you can’t do that with a flexible pull-through brush.
The JB Compound goes on the brush to the top of all the bristles. Butter that brush like an ear of sweet corn! And don’t worry about damage to your bore. World-class benchrest shooters clean their barrels this way and I have cleaned hundreds of airgun barrels the same way over the last three decades. A brass or bronze bore brush cannot damage a steel airgun barrel. Don’t use it on a brass barrel, but there is no harm when the barrel is steel.
The barrel was surprisingly clean. Usually I meet hard resistance for thee first 10–12 strokes in both directions, but the S4000E barrel got smooth in two passes. I still scrubbed it 20 strokes in both directions, followed by a thorough cleaning of the bore with several popular solvents, followed by a thorough drying. You don’t want to leave any moisture in the bore because the heat of the compressed air can top 1,200 degrees F. at the breech. It only lasts for a fraction of a millisecond so it is adiabatic, but solvent droplets could explode.
I shot the S4000E several hundred times at 25 yards, learning the quirks of the rifle. A gas piston air rifle is usually sensitive to its hold and this one is no exception. If you try to hold it like a deer rifle you will be disappointed. And 25 yards is more revealing than 10 meters when you want to know real accuracy.
One of the secrets is to use the artillery hold. If you have watched old war movies you have seen the barrels of field artillery pieces recoil several feet each time the gun fires. Yet field artillery is extremely accurate many miles downrange. The secret is that while the barrel recoils, the gun carriage is immobile, having been pinned to the ground or having dug in its carriage feet into the soil. The gun can recoil all it wants, as long as the carriage remains still. The shell always leaves with the muzzle in the same place, which is the secret to accuracy.
With an air rifle you become the gun carriage. You can’t hold the gun the same way repeatedly, so you don’t try. You hold it as loosely as possible and let it recoil as much as it wants to. Do this and your two-inch groups at 25 yards will become half-inch groups — it’s that dramatic! So the artillery hold is the first key to an accurate spring-piston airgun, but with a gas piston gun there is a second step.
Relax — that is the big secret! Get into your hold, put the crosshairs in the center of the bull, then close your eyes and relax. Relax completely! Open your eyes, and, if the crosshairs are still within a half-inch of where you want to shoot, line them back up and take the shot. If they aren’t, adjust your hold and body until they stay there. This procedure guarantees that when the rifle recoils it won’t go in some direction that your body is spring-loaded to send it. It will always recoil the exact same way every time.
If the crosshairs move when you relax, try shifting your elbows, your feet and even the position of your hand on the rest. Don’t stop until those crosshairs stay where you want them when you relax. I forgot to relax the first day I tested the rifle at 25 yards and my reward was a bunch of 1.5 to 2.5-inch five-shot groups at 25 yards. But within many of those groups there were three pellets touching. That was what tipped me off. The rifle wanted to shoot, but I wasn’t relaxing before each shot. That first day I shot about 125 shots to no avail.
The next day was similar. I even removed the scope and replaced it with a fine UTG reflex dot sight that has always proven reliable, and still I got large groups with several tight smaller groups inside. Seeing that the dot sight was no advantage I replaced it with the 4-power scope that came with the rifle. And still there was no joy. Until the end. At this point I had fired 90 shots. And then I remembered how important it is to relax. It’s really a prelude to a perfect follow-through, which we all know is the best shooting secret.
Shots 91 to 95 were taken with JSB Exact RS pellets and look what happened! Five pellets landed in 0.957-inches at 25 yards. I know that isn’t as tight as I would like to see, but I had been shooting for several hours to get to this point!
By this time in the day I was very tired. One good group under my belt was enough. Rather than shoot another, I adjusted the scope two clicks up and two clicks to the left and put the rifle away. The next morning I would be rested and ready to do my best.
The Next Day
I did great! The first two shots went where they had gone the day before because of scope stiction (the crosshairs don’t move when the adjustments are made, but after one or two shots they are jarred loose and suddenly shift to the new location). The first group I shot was five JSB Exact RS pellets in 0.547-inches at 25 yards. I relaxed for each shot and really concentrated on doing my best. It paid off. The S4000E rifle is accurate — just like I thought.
To affirm the accuracy I wanted to shoot a 10-shot group. That would show that the two good five-shot groups from the day before and earlier this day were not flukes. I shot the same way as before — relaxing before each shot. After five shots I could see that it looked good, and I hoped I wouldn’t tense up on the final five.
On the second five shots, though, something remarkable happened. I could feel in my off hand when the shot was ready to go. The rifle felt dead-calm in my hand and I knew the pellet was going to the right place. As a result, the final five shots did not change the size of the group. Ten shots went into 1.134-inches. But look at the group. Seven of those 10 shots are in 0.725-inches.
Stoeger’s S4000E is a welcome new addition to the breakbarrels that are available. For a street price of about $150 retail you get power and accuracy that used to cost $100 more. The rifle comes with both open sights and a 4x32 scope and mounts. I found the scope clear and bright at 25 yards and it was even possible to see the pellet holes in the black bull at that distance.
I thank Benelli USA for the opportunity to test this new addition to their airgun line. For more information please visit: usa.StoegerAirguns.com.