SIG Sauer created the revolutionary ASP20 air rifle from a clean sheet of paper. Gaylord walks you through the entire project and tests the results in this two part report! (Photo provided by SIG Sauer.)
September 03, 2019
By Tom Gaylord
Introduction This article will be in two parts. A new American breakbarrel spring gun has been created and the creators, SIG Sauer, opened their New Hampshire plant last year to show the airgun media what they were doing and how they were doing it. In this part we will first tour the SIG plant, where we show how SIG builds firearms in general, then specifically we will see the ASP20 rifle being created on the production line. Then they will take us to their company range and let us try the rifle for ourselves. But wait — there’s more!
SIG is so certain that their new rifle will revolutionize airgunning that each writer who attended the tour was given a rifle with a new scope that was made specifically for the rifle. That allowed them to test it on their own in any way they desired, away from corporate controls. We’ll see how that turned out for me when I test the rifle on my own in part two.
Media Tours SIG Sauer In late July of 2018 a number of airgun writers and editors were invited to SIG Sauer in New Hampshire, to witness the start of the ASP20 production line, and to tour their Exeter facilities. On travel day the east coast was slammed by thunderstorms, so not all invitees were able to make it. Those attending were Tom McHale who writes for American Handgunner, Shooting Illustrated, Concealed Carry magazine, and too many other publications and websites to list. Kristen Voss from the digital side of American Rifleman magazine represented the NRA. Terry Doe and Dan Chart attended from Archant Limited, the publisher of Airgun World and Air Gunner magazines in the United Kingdom. John Bright of Highland Outdoors, a worldwide firearms and related products distributor headquartered in the UK was also there. And I represented Firearms News .
The Tour SIG’s plant is huge. This is one small corner. (Photo provided by SIG Sauer.) This visit was a one-day event to showcase the startup of the ASP20 production line to the media. The ASP20 is a new breakbarrel air rifle that I will now tell you is the FWB 124 of the 21st century. By making that comparison I’m saying this new rifle is fabulous! I will show you every unique and novel new detail, then in Part two I’ll conduct an extended test of the rifle for you.
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SIG builds much of this rifle in their Exeter, NH, plant. It’s the same plant that makes the M17 and M18 sidearms for the American military.
Security Is Tight If you remember the old Johnny Cash song, One Piece at a Time , where he stole a Cadillac over 20 years of employment on the production line, our Bureau of Alcohol, Tobacco, Firearms and Explosives (BATFE) doesn’t share that humor. They don’t want firearms walking out in lunchboxes, so everybody going into and out of the plant has to pass through security. And I mean everybody — even the vice president of SIG Air had to remove all metal from his body and step through the detector.
Ground Rules Once inside we were taken to a small conference room where the ground rules of the plant tour were covered. Besides the BATFE, SIG has an Army contract for the new M17 and M18 pistols, and the Army requires them to keep that work separated from the commercial firearms being made in the same plant. The M17 military sidearm is based on the commercial P320 pistol, with some variations, and the Army does not want their pistols to get mixed in with civilian handguns.
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All good companies have meetings before each shift starts. SIG holds them in small groups at each of their work centers. All military contract parts are stored in color-coded cabinets and all assembly of the military firearms is done inside locked steel cages inside the plant. We were not permitted to photograph the cages, but they are nothing more than a standard shop area that’s been enclosed by a steel security cage for this contract work.
We were also asked to not photograph any engineering documentation, to include displays on the screens of any of the dozens (hundreds?) of CNC machines. There were also certain machining operations we were asked not to photograph. Otherwise, we were given full rein to take whatever pictures we wanted, and believe me, everyone had a camera!
SIG Director of Media Relations and Communication, Joel Harris, conducted the first part of the plant tour, showing us the general plant operations. SIG considers the airguns they make to be as important as their firearms, and they make them in the same way, to the same standard and in the same place! That, by itself, represents a departure from practices at other firearms manufacturers who also build airguns — though there are very few who still make their own. Most firearms manufacturers source their airguns from outside the USA, usually from somewhere in Asia.
Rapid Change Before we walked down onto the plant floor we looked out over a sea of CNC machines that I was unable to count. They told us they have been upgrading the plant capability by switching to 5-axis machines that can do more work than the machines they replaced. But that wasn’t the big deal.
They also have CNC machines with robot arms inside, moving the parts around the inside of the machine to get more operations from a single machining center. That’s efficient but it’s not the big deal, either.
The Big Deal The big deal is that a short time (days) before we arrived these CNC machines that were running briskly had not been installed. Other companies take days to install one machining center and get it up and running, SIG installs dozens of them at a time and usually has them running in one shift.
And even that wasn’t efficient enough for them. They did something I have never seen. They installed robot arms between two CNC machining centers and had the arms unloading finished pieces from one machine and installing them into the carriage of the other machine. In other words, no operators for the entire process! I have seen robots inside machining centers but this was the first time I have seen them operating between two separate centers without
Finishing A robot arm (the yellow in the background) is holding a pistol slide against a grinding wheel to remove the tool marks from the various angles on the steel part. This machine has several wheels and sanding belts that come into play at different times. Please excuse the blurriness from the speed of the robot and photographing through a Plexiglas enclosure. (Photo provided by SIG Sauer.) After walking around the plant we were taken into the finishing room. In there everybody had to wear hearing protection because of some of the loud machines like the huge industrial tumblers. I saw a robot grinder that was smoothing the pistol slides we had just seen being made. Everything was inside a Plexiglas enclosure, and the robot arm worked fast.
A solid block of steel goes into the machining center and all the machining operations are done. A lot more needs to happen before this slide will be complete, and there are other machines for that. (Photo provided by SIG Sauer.) Test Firing Each pistol SIG produces is test-fired on one of six indoor ranges inside the factory. Between the pistols and their semi- and full-auto firearms, SIG fires over a million rounds of ammunition each month! And, when I say they shoot each gun, I’m not talking about proof-tests. I’m not talking just about military contracts and law enforcement products. I’m saying they test each and every gun they make — period! Human beings firing groups!
We were allowed to see the test ranges but not to take photos. SIG also has a 100-yard indoor range for their rifles and submachineguns in the same plant.
Now, To The ASP20 The plant tour was fascinating, but it was only shown to us because SIG treats its airguns the same as they do the firearms they manufacture. They made us aware of the care that goes into everything they produce. And you don’t want to read about a plant tour. You want to know about the new Advanced Sport Pellet rifle — the ASP20. The name was created when the company was still thinking in a European way, because “Sport” in Germany, when it relates to airguns, means everything besides 10-meter target guns. The Germans are big on target shooting with airguns and not so much on anything else. The rest of the world knows airguns can do many more things besides target shooting, but SIG is a German company.
The number 20 refers to the rifle’s muzzle energy in .177 caliber. Twenty foot-pounds from a .177 caliber spring rifle is really pushing the performance envelope. To get that high any other airgun maker would just put way too much mainspring behind a piston that’s too fat with a stroke that’s too long and they’d call it hasty pudding. SIG went a different way. They reckoned if they could make a .177 spring-piston rifle that was easy to cock, insensitive to how it’s held and dead-nuts accurate — all at the same time, how nice would that be? What I am about to show you is the most significant development of the spring-piston airgun that has ever taken place since the first ones were produced in 1905!
The Engineers Take Over SIG had three engineers on this project. Ed Schultz, formerly of Crosman, was one. He’s the man who created the Benjamin Discovery and the Benjamin Marauder, among many others. The second engineer, Krzysztof (Kris) Kras, came over to the team from the firearms side of the house.
A third engineer, Justin Daniel Heckert, also formerly of Crosman, sadly passed away unexpectedly on February 22, 2018. He was beloved by everyone on the development team, and SIG has memorialized him by including his initials, JDH, in the serial number of every ASP20 rifle. Serial number one was presented to his family.
The ASP20 Air Rifle Assembly Line
Ed Schultz, center, conducted the tour of the air rifle assembly line. At this point Ed Schultz took over as our tour guide and led us through the brand-new ASP20 assembly line. It was one day old! He narrated the building of a complete rifle before our eyes.
Laser-Welded Parts The spring tube and barrel with attached base block and silencer showed up on the assembly line as finished assemblies. They had been laser-welded in another SIG facility and brought to this building, however that would change. The laser that welded them was moved to this plant but hadn’t been installed yet when we were there. As I mentioned — this was day two of production and things were still getting sorted out.
SIG bought a 2,000-watt industrial laser to weld the spring tube and barrel together. (Photo provided by SIG Sauer.) SIG already owned a thousand-watt industrial laser but it wasn’t big enough for this airgun job so they bought a new two-thousand-watt laser just for this project! Other companies weld the same parts (barrel, base block and spring tube) by friction or with induction welding, but SIG wanted the least possible distortion, making the laser the way to go.
The Cocking Shoe Many of the media members who attended are also accomplished airgun tuners. They could appreciate what SIG did with the cocking link and shoe! Speaking of innovations, let’s start with the cocking shoe, which is the interface between the barrel’s cocking link and the piston. The shoe in this rifle is made from hard zinc, and before you go ballistic about SIG trying to save 20 cents on a part, it was designed that way for a purpose. It hooks into the steel piston to cock the rifle, and when zinc contacts steel it has less friction than steel against steel. They lubricate this part for life during assembly and this shoe was tested over 19,000 cocking cycles at a force 25 percent greater than what will be applied in use.
The spring-loaded cocking shoe (arrow) changes its angle as the cocking stroke progresses. The shoe is articulated (it rotates through a small arc) and is spring-loaded to eliminate most of the friction that a rigid steel cocking shoe would have. Airgun tuners know that they have to deburr the cocking slot, the cocking shoe and the piston when they tune a springer. Even then, the cocking shoe will try to gall (rub with pressure great enough to melt and score metal) the insides of the spring tube. SIG designed a shoe that articulates with the changing angle of the cocking link and also lubricates itself as it moves.
Matchlite Trigger Ed Schultz (black shirt) shows me the Matchlite trigger being assembled. (Photo provided by SIG Sauer.) Next we were shown something shocking — an American-made air rifle trigger called the Matchlite! Airgunners will want to know if it’s as nice as a Weihrauch Rekord trigger, which is the standard. That’s a judgment call, but I will tell you how this one is designed and what it does.
SIG Thinks Inside The Box! When I was first shown this rifle at the 2018 SHOT Show, SIG bragged about the Matchlite trigger. I told SIG Air vice president, Joe Huston, that shooters were going to fiddle with the adjustment screws. Historically they do that with every new airgun trigger. When Beeman warned them not to fool with the Rekord’s sear engagement screw 51b, it was like a neon sign, telling them where to start! For some odd reason, Joe just smiled back at me and said nothing.
The Matchlite trigger comes with two adjustments — one for pull weight and the other for the length of the first stage pull. The lowest pull weight is 2.5 lbs. and the highest is 3.5 lbs. An adjustment screw allows you to adjust between these limits in 2-ounce steps. Period! The screw bottoms out when turned to the limit in one direction and turns without effect when it reaches the other limit. Between the two limits you have full control to set the pull where it best suits you.
The Matchlite trigger has been designed so all the adjustments are contained within this performance “box.” The other adjustment is the length of the stage one pull. If you don’t want a 2-stage trigger, stage one can be adjusted out. If you want a long first stage you can have that. When I get a rifle of my own to test, I will verify that.
SIG has given us a sporting trigger that’s light, crisp and can be adjusted to suit — to the limit of the adjustment parameters. If that was all there was it would be fabulous, but now let’s look at the trigger that I watched being assembled part-by-part.
This is a graphic of the trigger, assembled. (Photo provided by SIG Sauer.) We watched the worker assemble each part of the trigger. He used a special fixture to hold the parts while the pins were pressed in.
The trigger blade is a special polymer, reinforced with fiberglass. It is relatively straight and feels quite positive when pulled.
SIG has selected a two-hump contact design for the sear that works in concert with their stage adjustments. When you adjust the first stage length you are moving the pivot point of the setup. This same design approach can be seen in Mauser military triggers, but SIG has taken it to a different level to make the adjustments exact and precise.
They Balanced The Trigger! “And then, at step two, a miracle occurs…” is the punchline to a scientific joke. Well, at SIG, it ain’t no joke! They actually balanced the trigger assembly!
I photographed this back in the conference room, after the tour, The Allen wrench passes through the trigger pivot pin hole and, as you can see, the trigger is balanced. The parts that were used in the trigger were both dimensioned and made from materials that allowed the finished unit to balance, fore and aft, on its pivot pin. That makes it extremely sensitive to each adjustment!
Anti-Beartrap SIG put an anti-beartrap device in the trigger to prevent accidents. As all airgunners should know, you NEVER release the barrel of a breakbarrel rifle while it’s open for loading! There are safety features designed into most airgun triggers to prevent the barrel from snapping shut violently, but anything made by man can fail. Your fingers could be seriously injured if the breech closed on them. I didn’t appreciate how much the general public does not understand this until we were at the range later in the day and I saw several of our tour group who are not airgunners release the muzzle of the rifle as they loaded the pellet. They were all corrected, of course.
Assembly Continued The pivot pin fits into the hole drilled through the action forks and base block. These parts remain together from this point on. The pin is held in by a single Allen screw, because no sideways force is needed. As assembly progressed, Ed showed us the barrel and breech. They are held in the action forks by a large pivot pin that the barrel rotates on when the rifle is cocked. The number one problem with a breakbarrel rifle is barrel droop, which means the barrel points down, relative to the sight line. Special scope mounts are made to counter this problem that almost every breakbarrel has. SIG decided not to have the problem, so when they bored the hole for the pivot pin, they bored the spring tube forks and the breech together! They were held in alignment as the one hole was bored. Afterward, that barrel remains mated to that spring tube for life.
Other airgun companies create solutions to fix the barrel alignment problem. SIG designed the problem out, altogether!
This way the barrel never gets out of alignment with the spring tube. They cannot get out of alignment, because of the second brilliant thing — SIG invented the Keystone breech!
The Keystone Breech The Keystone breech works by flanges (arrows) that bear against the sides of the action forks when the barrel is closed. The spring-loaded detent below the breech and lubed with gray molybdenum grease, slips under its catch in the action forks, drawing the breech tightly down into the action forks. The number two problem with breakbarrels is a barrel that wobbles from side to side in the action forks when it’s closed. Not all guns have the problem, but way too many do and there is little or nothing that can be done to fix many of them. SIG decided not to have this problem, either. They invented a breech that locks the barrel tight without requiring spring-loaded locks. It had no name when we saw it at the SHOT Show and again six months later on the tour, but unofficially everyone was calling it the Keystone breech. When you see the shape you will understand why.
Piston And Gas Spring Assembly The ASP20 is powered by a pressurized gas piston. The piston has a conventional seal up front and some sort of synthetic ring at the back to cancel vibration. The piston seal was lubed with what appeared to be molybdenum disulfide paste.
SIG installs the piston by hand just like the rest of us. Care must be taken to avoid nicking the piston seal in this process. We were shown the installation and lubrication of the piston seal, followed by its installation into the spring tube. Like spring gun tuners everywhere, the SIG workmen have to take this step carefully, or risk cutting the seal on sharp edges in the tube. They did a good job, but I expect a few more special tools were created for this procedure after we left. I know I need them.
Why does SIG use a gas piston in the ASP20? Gas pistons are more modern. They don’t take a set if left compressed. They are less susceptible to cold and, if the design is right, they operate smoother. They also eliminate several parts that rattle and they remove some weight from the powerplant.
One More Brilliant Feature SIG did away with the washers and just machined washer-shaped flats (arrow) on both sides of the base block. Nothing can slip out of alignment during installation. If you have ever disassembled a precision breakbarrel spring gun, you have probably encountered the thin shim washers that help the base block (the party that holds the breech) rotate between the action forks during cocking. In some rifles those thin washers can be a pain to install — especially when the rifle is new and the action forks are tight. SIG did something very clever here. They machined flats on the base block that take the place of those washers and can never slip during installation! Just lubricate them and slide the base block into the action forks.
Other breakbarrel guns like this Diana 45 have separate thin washers that must be lubricated and are often hard to install when assembling the rifle. The Silencer Three synthetic spools snap together to make up the technology of the ASP20 silencer. Now let’s look at the silencer/moderator on the front of the barrel. It is indeed an active silencer containing three synthetic spools that look like old-fashioned hair curlers.
Silencer-Wrap Each silencer spool is wrapped with felt. Each spool is wrapped with felt to absorb the sound of the compressed air. The small spiny projections on the spool hold the wrap in place. I will have more to say about this silencer later.
Final Assembly — The Stock I have passed over many small things in assembly that are standard. I wanted to hit the high points of innovation for you, and even that has taken a long time. Now it’s time to drop the assembled barreled action into a stock.
The barreled action fits into the stock in the conventional way. SIG offers the rifle in either a wood or synthetic stock. The synthetic stock saves 8 ounces of weight and eighty dollars in the retail price, but it looks very similar to the painted wood stock.
At some point the synthetic stock will be offered with an optional adjustable comb/cheekpiece. The elements necessary to make that possible were put into the initial design, but, since mold parts take a long time to fabricate and wood is quicker to bring to market, they brought out wood first. I tested the rifle in its wood stock, both at the factory and several months later in Part two when they sent me a rifle of my own.
The Barrel The assembly was over, so we left the plant floor and returned to the conference room for a final discussion and small presentation before adjourning to the range. This was where I got to ask about the barrel.
SIG rifles their own barrels. They use the same precision seamless tubing from which all quality airgun barrels are made. However, as tight as the tubing dimensions are held during its manufacture, reaming and honing the tubing before rifling makes it even more uniform. It costs more to do it that way and the improvement in accuracy isn’t that great, but it is there.
I asked whether there is a leade in the breech. Yes there is. This helps you load those longer pellets, because they don’t bite into the lands as quickly. A two-part leade tapers gradually into the rifling.
A sectioned barrel showed the SIG had well-rifled lands. The barrel has 12 lands and grooves, which is pretty standard for an air rifle. The twist is 1 turn in 450mm, which is 1:17.72-inches. Lothar Walther uses the same twist rate for some of their airgun barrels.
The barrel is not choked. I asked and Ed smiled. He said, “After you shoot today, you tell me if you think it needs to be choked.”
Off To The range After lunch we boarded several in their fleet of black SUVs, and headed to the range 7 miles away. On a 300-acre campus SIG has put more than 40 firearm ranges that run from 15 yards to 1,000 yards. The public is welcome to attend special classes given on these ranges.
The ranges are also used for law enforcement and the military, and there were a couple ranges we were not allowed to see. Is this where covert things are practiced? They run ranges day and night and use cars, buildings and other structures to simulate the real world. I jokingly asked where the Las Vegas cop had learned to shoot through his windshield while driving and a particular range was pointed out!
We shot the air rifles on an indoor range that goes to 50 meters. There were only two firing positions and more than 8 of us, so we took turns. Terry Doe volunteered to go first, so Ed Schultz nominated me for the other bench. Terry was the 1991 field target world champion, so I guess Ed felt some balance was needed. Or perhaps comedy relief!
Shooting Sensation I started out shooting with an artillery hold. (Photo provided by SIG Sauer.) I started with the .177 caliber rifle. Shooting was off a bench that had a semi-hard bag for a rest. Thinking that a gas spring rifle needs the artillery hold, I assumed that hold immediately. The artillery hold allows the rifle to move freely and without restraint in recoil.
Terry Doe shot with the rifle rested on the bag and got the smallest group of the day — an inch for five shots at 50 meters/55 yards. Terry Doe rested his rifle directly on the bag. That doesn’t usually work with a powerful springer, but he shot the smallest group of the day. After seeing that, I switched and was rewarded with better accuracy. That is a reflection on just how smooth the ASP20 is.
Terry Doe put five pellets into an inch at 50 meters/55 yards. The triggers on both test rifles were set with a medium length first stage, which is how I like it. The rifles had been sighted-in so all we had to do was aim and shoot. The second stage of the trigger broke crisply — as nice as a well-adjusted Diana T06 trigger.
There was a little recoil jolt and no vibration. I mean none — as in zero, zip, nada, null, void of, and lacking in all respects. If the rifle hadn’t jolted, I wouldn’t have known that it fired. I would compare the firing sensation to that of a tuned HW50.
It was also surprisingly easy to cock. SIG engineer Kris Kras told me that their design goal was a breakbarrel with a cocking effort of less than 40 pounds. Kris developed a mathematical model that predicted a 36-pound effort for their final design, and when they tested the pre-production prototype it cocked at 35 pounds. The first production rifles are coming off the line at bang-on 35 lbs. cocking effort.
While that number sounds high, compared to the FWB 124, you have to remember — the ASP20 produces 20+ foot-pounds in .177 and 23 foot-pounds in .22, where the 124 that cocks with 10 pounds less effort was lucky to make even 12 foot-pounds! Any other air rifle that develops power similar to the ASP20 would cock with around 50 pounds effort, if not more.
Discharge Sound You cannot tell how loud a spring gun is when you shoot it, because most of the noise travels through your cheekbones right into your ears and the rifle sounds loud. When someone else shoots, you hear how it really sounds and the ASP20 is not that bad. It is certainly quieter than any other 20+ foot-pound spring rifle. Is it backyard friendly? That depends on the yard, your neighbors and the laws where you live. The noise level is partly due to the silencer and partly to the smooth gas piston.
Day Is Done The SIG tour was wonderful and I learned a lot about the rifle that would never have come to light any other way. But I wanted to get one of my own so I could test it my way — where I could shoot a lot longer and be more thorough!
Thanks My thanks to SIG Sauer and to the SIG Air team of folks who made this tour most interesting and informative. They afforded all the media folks a rare opportunity to look behind the curtain and see things that are seldom revealed to writers.
Summary I’m not done testing the ASP20, but I am finished with Part one of this report. SIG Sauer has designed a spring-piston air rifle from a clean sheet of paper that performs like a custom rifle out of the box. It’s 100-percent American designed and made, which is a story in itself. Keep an eye out for part two of this article!
Read part two here .
SIG SAUER ASP20 AIR RIFLE SPECIFICATIONS Manufacturer : SIG Sauer
Model : ASP20
Calibers : .177 and .22
Length : 45.6-inches
Weight : 8.5 lbs unscoped, 9.75 lbs scoped
Pull : 13.8 inches
Sights : None, but a Picatinny rail for scope
Stock : Wood or synthetic
Price : $430 wood, $350 synthetic
Scope : Whiskey3 $350 (bundled for less)
