by Tom Gaylord
Writing as B.B. Pelletier

Sig Sauer’s new ASP20 gas spring breakbarrel air rifle breaks ground in many areas!

Part 1
Part 2

This report covers:

  • Why a gas spring?
  • Trigger
  • Why a breakbarrel?
  • Does the ASP20 have an internal shock absorber?
  • On with the build
  • Final assembly — the stock
  • The barrel
  • Off to the range
  • Shooting sensation
  • Cocking effort
  • Accuracy
  • Whisky 3 ASP 4-12X44 scope
  • Summary

Boy, is there a LOT of interest in this new rifle! You guys are asking a lot of very good questions about the new ASP20 breakbarrel rifle, as you should. I will begin by addressing some of the most prominent ones.

Why a gas spring?

Some call it a gas piston, others say gas ram, but we are all referring to the gas spring (the industry term for a spring that uses compressed gas in place of a coiled steel spring to do its job). Gas springs replace coiled steel mainsprings in spring-piston airguns. They are more modern and easier to make and obtain, they don’t take a set if left compressed, they are less susceptible to cold and, if the design is right, they are smoother operating. They also eliminate several parts that rattle and they remove some weight from the powerplant.


Why does the trigger stop at 2.5 pounds on the lower end? Someone yesterday said they wished the trigger adjusted down to 6 ounces like a Rekord, but the only Rekord that does that safely is the target Rekord found in the HW55. The standard Rekord stops at about a pound. Messing with screw 51B (the sear contact area) is dangerous! The Diana T06 is about the same, if not a little heavier on the low end.

When a trigger breaks cleanly, 2.5 pounds is very light. For a trigger on a hunting rifle generating 20+ foot-pounds, it’s as light as you need. Remember, when it’s cold your fingers will loose sensitivity. I’m sure there will be discussion about this, but that is the reason.

Why a breakbarrel?

Several readers asked why Sig didn’t just make a sidelever or an underlever — assuming those designs are somehow better. Sig designed this breakbarrel to be just as accurate as any sidelever or underlever and to save a couple pounds of weight and some cost at the same time. If they got it right, a breakbarrel was the way to go. We shall see how they did today.

Does the ASP20 have an internal shock absorber?

There is no internal shock absorber in the ASP20. You only need that when there is vibration to be absorbed. The ASP20 doesn’t vibrate, so nothing is needed. The Anschütz 250 (a target rifle of the 1960s) had an internal shock absorber, yet was well-known for its vibration. It’s better to design the gun right than to build in gimmicks that fix the problems.

On with the build

We left off yesterday with the powerplant being assembled. I didn’t cover the silencer/moderator/lead dust collector (ha ha!) on the front of the barrel. It is indeed an active silencer that contains three synthetic spools that look like old-fashioned hair curlers.

ASP20 silencer spools
Three synthetic spools snap together to make up the backbone of the ASP20 silencer.

ASP20 silencer wrap
Each spool is wrapped with felt. The small spiny projections on the spool hold the wrap in place.

Final assembly — the stock

I have passed by many 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 barreled action into a stock.

Some readers have commented on the strange shape of the stock. Sig patterned it after the German SSG 3000 sniper rifle stock. The first offering of the ASP20 will be in a black wood stock. Why? Because wood is easier to profile than injection molds are to fabricate. Instead of spending many tens of thousands of dollars creating the mold parts for a synthetic stock, Sig decided to launch the rifle with the wood stock first.

ASP20 stock
The barreled action fits in the stock in the conventional way.

They are still refining small design decisions for the synthetic stock, like should they offer an adjustable comb/cheekpiece as an option? They have already put in the design elements necessary to make the adjustable comb possible, but these mold parts take a long time to fabricate and wood is quicker to bring to market. So, Mrs. Calabash — do you want the rifle in September/October, or can you wait until next February? I’m making those dates up, but they represent the kind of timeframe the SigAir team is wrestling with. I shot the rifle in a wood stock and that is what I am about to report. It’s also on the rifle that I will test for you.

The barrel

We left the plant floor and returned to the conference room for a final discussion and presentation before adjourning to the range. This was where I got to ask about the barrel.

Sig rifles their own barrels. They use precision-honed seamless tubing. Do you remember the Benjamin Maximus and the fact that it has a slightly more accurate barrel than the Discovery? Honing before rifling is the reason. Most airgun barrels are rifled from seamless tubing that is held to a tight tolerance in manufacture. But, as tight as they hold the dimensions, reaming and honing the tubing makes it more uniform. It costs more to do it that way and the improvement in accuracy isn’t that great, but it is there.

Next I asked about the breech. Is there a leade (a taper to the rifling at the breech) to help with loading the pellet? Yes there is. There is a two-part leade that tapers gradually into the rifling.

The barrel has 12 lands and grooves, which is pretty standard for an air rifle. The twist is 1 turn in 450 mm which is 1:17.72-inches. I know for a fact that Lothar Walther uses the same twist rate in some of their airgun barrels.

The barrel is not choked. I asked, and Ed sort of smiled. He said, “After you shoot it today, you tell me if you think it needs to be choked.”

ASP20 barrel
We saw a sectioned barrel, but it did not show the breech.

Off to the range

After lunch we boarded Sig7, their black SUV, 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, and several times while I was in New Hampshire people outside our tour group, seeing the SIG logo on shirts and such, came up and volunteered that they had attended one or more classes and loved them! Even the desk clerk at the hotel where I stayed said the same thing when I checked in. If I lived in the area I know I would attend.

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 where covert things are practiced? They run the ranges day and night and use cars, buildings and other structures to simulate real life. 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 airguns on an indoor range that goes to 50 yards. Needless to say the ASP20 was first on the list, but, as there were only two firing positions and more than 8 of us, we took turns. Terry Doe volunteered to go first and Ed Schultz volunteered me. Great! Me, next to a world champion shooter. I guess Ed wanted some balance.

Shooting sensation

I started with the .177 caliber rifle. Shooting was off a bench that had a semi-hard bag for a rest. Knowing that a gas spring rifle needs the artillery hold, I assumed that hold immediately.

ASP20 Tom shoots 1
I started out shooting with an artillery hold.

The trigger was set with a medium length first stage, which is how I like it. And the safety is manual. Take it off and act like a big boy. Put it back on when you need to — not when the nanny committee thinks you should!

The rifle had been sighted-in so all I had to do was aim and shoot. The second stage of the trigger broke crisply — as nice as a T06 trigger, if a trifle heavier. And then came the sensation of firing.

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 my R8 or to a tuned HW50.

After my first shot I turned to Ed Schultz who was watching my target through a spotting scope and I told him this is the first gas spring air rifle that hasn’t slapped my cheek when it fired! It feels like a TX200 Mark III, which I guess is the point. Remember that synthetic ring at the rear of the piston? A large part of the lack of vibration is due to that. Not all, though. Sig has paid scrupulous attention to every detail in this rifle, to make it shoot smooth.

Cocking effort

At dinner that evening I talked with Sig engineer Kris Kras, who told me Ed had requested up front they design a breakbarrel with a cocking effort of under 40 pounds. Kris developed a mathematical model that predicted a 36 pound effort, based on the design, and when they first tested the prototype it was 35 pounds. The production rifles are coming off the line at bang-on 35 lbs. cocking effort.

While that number sounds high after all I have said about the rifle being the new FWB 124, you have to remember — this one gets 20+ foot-pounds in .177 and 23 foot-pounds in .22! Any other air rifle in this category would cock with around 50 pounds effort, if not more. There were three women shooting with us this day and all of them were finding the rifle easy to cock. A couple who aren’t airgunners had to learn to hold the barrel at the muzzle to use all the leverage, but they did it without complaint. Would less cocking effort be better? Sure. I would also like to weigh 160 pounds, have hair and have a sixpack instead of a keg, but the laws of physics and nature have to be obeyed! (rim shot!)

Discharge sound

At this point I started listening to Terry’s rifle as he shot. You cannot tell how loud a spring gun is when you shoot it yourself, because most of the noise is in the powerplant — not coming out the muzzle. The sound travels through your cheekbones right to 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 that hasn’t been tuned. I would put the discharge as equal to my Diana 34P that I tuned with a Vortek spring kit. That rifle also doesn’t vibrate and vibration is where most of the noise comes from. Is it backyard friendly? That depends on the yard, your neighbors and where you live.


Okay — I have waved the big juicy sirloin steak in front of you dogs for three days now and I got you slobbering all over yourselves. I will make this pretty brief because I am still going to thoroughly test the ASP20 in .22 caliber for you. And, I will remain as skeptical as I always am when testing.

I started shooting with the ,177 caliber rifle at a target just 7 yards away, to verify that the scope was sighted for me. I hit just to the right of the aim point and at the same level. Then I reached out to 35 yards and shot a couple, all the while being amazed that the powerplant is as smooth as it is. Definitely no slapping of the cheek when this rifle fires. Then I shot it a couple times at 50 yards. I probably put 3 or 4 into 1.5 inches. Remember — I was using the artillery hold. That fact is about to become important.

Ed then asked me if I would like to try the .22 caliber rifle. He felt it was a touch smoother, which it is. That’s why I asked for a .22 caliber to test 6 months ago when Sig asked me which I preferred. At this power level the larger caliber is always a trifle smoother.

Remember, too, that Terry Doe, a world champion airgunner, was shooting on the bench next to me. I looked over at him and, lo and behold, he was resting the rifle directly on the sandbag. Golly! Doesn’t he know?

ASP20 Terry shoots
Terry Doe shoots at 50 yards with the ASP20 resting directly on the bag!

Oh! Wait! Maybe he DOES know! Maybe this rifle is so smooth that it can be rested directly on the sandbag. By this point I had shot the .22 caliber rifle at 7 yards and knew its scope was on. Then Ed mentioned something about the scope I am using.

Whisky3 ASP 4-12X44 scope

I listened to Ed before proceeding. The Whisky3 was developed for the ASP20 and, besides being a bright, clear optic, it does something I have never seen done well before. Sight it in at one distance (or was it two?) and you can then dial the elevation knob to adjust for any distance you are shooting. When I returned to the shooting bench I tried it. Ed showed me that the scope on the rifle I was shooting was set at 7 yards — its closest focus distance. He then dialed it to 35 yards and told me to try a couple shots. This time I rested the stock directly on the sandbag. Ed said to rest it just forward of the triggerguard.

I shot two pellets at 35 yards and they hit dead-center on the aim point with their holes touching. So the direct rest worked. Then I dialed the scope to 50 yards and shot at the far target. Once again, dead center. Ed was watching my target through the spotting scope and I told him to watch me shoot the second shot. This time when I shot, the hole at 50 yards stayed the same size. The scope was set on 12 power and Ed had a more powerful spotting scope, so I asked him what he saw. He said he never saw the hole increase in size! I either shot a second pellet through the same hole or I shot the rifle completely off target, which is an old marksman’s trick to impress newbies. Guys, I would have done that (the trick) but I wanted to know how accurate this new rifle is, so I was really trying. I never expected it to shoot through the same hole! Yes, Ed, I guess this barrel does not need to be choked!

The Whiskey3 scope is a real stunner! It retails for $359 by itself, but Sig is bundling it with the rifle for a whole lot less. One reader commented that bundled scopes are usually not good, and I would agree. This one is the exception.

Ed suggested that I not shoot a third shot at this target, because it might mess up my day. It probably would have, but at the same time Terry Doe was having the same good fortune on his 50-yard target with the .177 rifle. I did stop shooting after just two shots, but Terry went for a full 5 shots, and look at what he did.

ASP20 Terry's target
Terry Doe shot five .177 caliber JSB Exact 8.44-grain domes. Terry said this (it’s around one inch) group will only get better as he learns the rifle. Photo provided by Sig Sauer.

Oddly, I was also shooting .22 caliber JSB domes, so now we know what brand of pellets it likes. We also had some Sig Sauer Crux and Wraith domes to shoot, but I found them very hard to chamber.


Whew! I thought today would be the end of this report for sure, but there is still a lot more to come. I have pretty well covered the ASP20, though.

I’m taking a break tomorrow and writing about some gun from history. The last part of this report will come next week. This report has been fun, but I am also worn out! Have some pity on a tired old man and let me catch my second wind.