by Tom Gaylord
Writing as B.B. Pelletier

Sig ASP20
Sig ASP20 breakbarrel rifle.

Part 1
Part 2

This report covers:

  • Trigger adjustment
  • Whiskey3 4-12X44 scope
  • Today’s test
  • Velocity with the lead Crux Pb
  • JSB Exact Jumbo
  • JSB Exact Jumbo Heavy
  • How fast will she go?
  • Easy cocking!
  • Barrel loose when cocked
  • Trigger pull
  • First stage?
  • Summary

Today we will find out about the velocity of the .22-caliber Sig ASP20 breakbarrel rifle that I’m testing. Before we get into that, though, I have a couple things to address.

Trigger adjustment

First, reader Siraniko asked this:

“You will have to show us a picture how the trigger is adjusted while in the gun. The only picture I could find of how to adjust the trigger showed it while separated from the gun (/blog/2018/08/my-day-at-sig-sauer-part-2/).”

That’s a good question. He asked because I showed the bent Phillips screwdriver that’s used to adjust the trigger pull weight. So let’s discuss the trigger adjustments now.

Nearly all trigger adjustments on firearms and airguns are located at the bottom of the trigger assembly, where they are accessed through the triggerguard. Sometimes, though, the stock has to come off to get to them. The ASP20 has its two adjustment screws in two different places and both the stock and the scope can remain where they are.

The adjustment to move the point of the second stage engagement is located on the bottom of the trigger assembly in the conventional location. It’s difficult to see because the screw is actually hidden by the back of the trigger. But the Allen wrench through the hole in the triggerguard will go to the right place.

Sig ASP20 trigger adjust 1
The Allen wrench passes through the triggerguard and into the back of the trigger where it engages the first stage adjustment screw.

The other trigger adjustment is the trigger pull weight and is located at the top rear of the trigger. It’s accessed through a hole in the back of the spring tube cap, and, with the bent screwdriver Sig provides, the trigger can be adjusted with the scope mounted.

The adjustment screw is spring-loaded, so you have to push the screwdriver tool down to engage it. That is important. If I hadn’t tried it I might have overlooked that important step. The push is substantial, though the manual calls it light, so when you get your rifle, give it a try, even if you have no intention of adjusting the pull weight.

Sig ASP20 trigger adjust 2
Push down on the trigger adjustment tool and you can adjust the trigger pull.

The adjustment takes about a quarter-turn of the screw to change the pull weight by 2 ounces. So adjust, then relax and reposition the tool. Then push down and adjust again. Repeat until the trigger is where you want it. Clockwise increases the pull weight and counter-clockwise decreases it.

Whiskey3 4-12X44 scope

Several readers were fascinated by the way the Whiskey3 elevation scope adjustment allows you to keep the crosshairs on the target at all times. This is nothing new. Field target shooters have been doing the same thing for more than 20 years. They make custom scope knobs that they cover with tape and then write all the distances to the targets on the tape. Once they sight in the rifle at all ranges, it works well.

Firearms scopes have similar adjustment features but they don’t work nearly as well. They don’t because they are calibrated for a specific round of ammunition that the owners of the guns either can’t get or they refuse to pay for — preferring bargain ammo. They also don’t bother investing in the rangefinders that are needed to determine the exact distance to the targets. I’ve had shooters tell me that a target I knew to be at 75-yards was 200 yards away! Without a rangefinder many people can’t estimate range accurately enough to use a ballistic scope.

Without discipline and controls, a ballistic scope has no chance to work as designed. Field target shooters only shoot between 10 and 50 meters (11 and 55 yards), so they don’t have nearly the problems that firearms shooters have with this concept. They cannot use rangefinders in a match, but they have learned how to use the parallax adjustments of their scopes as a makeshift rangefinder.

They also don’t skimp on ammunition. Whatever pellet their rifle and scope are set up to shoot is what they will shoot, because they have taken the time to set all of this up.

What I’m saying is the Whiskey3 might actually be better on an air rifle than any other ballistic scope in use on a firearm today. I have to sight in the rifle and set the scale on the scope before I can test accuracy, so you will have a chance to look over my shoulder at how this scope is set up.

Today’s test

With that out if the way it’s time to look at the velocity of the test rifle. The ASG20 is not like any other air rifle I have tested, because it has that Whiskey3 scope mounted. The scope is set up to work with pellets in the 14.5 to 16-grain weight range. That comes from Ed Schultz of Sig. What that means is that for the pellet to always impact at the point of aim you must know the range to the target, set it on the elevation adjustment of a scope that has been sighted in and then use a pellet whose weight falls within that range.

Can you use other pellets? Of course. They just won’t adjust to the ranges marked the scope’s elevation knob in the way I have just explained. You can still sight in the Whiskey3 scope and use any pellet exactly as you would for any other airgun. Sig even gives you the original vertical adjustment knob with the mil scale, plus the knob’s cover. Just swap it for the range scale knob and you’re in business.

Velocity with the lead Crux Pb

I started with the pellet Sig set up the Whiskey3 scope to use — the Sig Crux Pb (lead). That is a pellet Pyramyd Air does not yet stock. The lead Crux is domed and weighs 14.66 grains, according to Sig. I weighed several and found them to weigh between 14.7 and 14.9 grains. Most of them weighed 14.7 grains, so I will calculate the performance from that weight.

Ten Crux lead pellets averaged 856 f.p.s. The spread went from 850 to 868 f.p.s., so a range of 18 f.p.s. At the average velocity this pellet produces 23.92 foot pounds of energy at the muzzle. So, with the first pellet the ASP20 has already exceeded its expected energy of 23 foot pounds (for a .22).

I have to mention the Crux pellets are not easy to load into the breech. I remember that from my time at Sig, and it appears they are still that way.

JSB Exact Jumbo

The second pellet I tested was the JSB Exact Jumbo. When I tested a rifle at Sig, this was the most accurate pellet and it also matched the trajectory set in the Whiskey3 scope. In the test rifle this pellet averaged 830 f.p.s. The spread went from 824 to 835 f.p.s. That’s a range of 11 f.p.s. At the average velocity this pellet produced 24.31 foot pounds of energy at the muzzle.

JSB Exact Jumbo Heavy

Next up were some 18.13-grain JSB Exact Jumbo Heavy pellets. They averaged 776 f.p.s. in the test rifle and the spread went from a low of 771 to a high of 780 f.p.s. That’s a range of 9 f.p.s. At the average velocity this pellet produces 24.25 foot pounds of energy.

How fast will she go?

The last pellet I tested in the rifle was the Sig Crux Ballistic Alloy dome. These weigh only 10.03-grains, which makes them fast! In the test rifle they averaged 1064 f.p.s. with a spread from 1056 to 1070 — a span of 14 f.p.s. At the average velocity this pellet produced 25.22 foot pounds of energy — the highest in the test!

I must note that these alloy Crux pellets loaded hard, just like the lead ones. In fact, I seated them deep in the barrel with a pen because my fingers got sore pushing them in directly. All the JSB pellets went in snug but easy.

Sig ASP20 seated pellet
I had to push the Crux pellets in to the breech with a pen.

For a brand new spring-piston air rifle the ASP20 is very stable. I feel it will probably continue that way for a long time.

Easy cocking!

Throughout this test I was amazed by how easy it is to cock the ASP20. The test rifle cocks with just 33 lbs. of effort! I could shoot this one for hours. And there is virtually no noise upon cocking. The gas piston is without sound when cocked.

Barrel loose when cocked

While carrying the cocked rifle back to my office after measuring the cocking effort, I noticed the barrel was swinging freely. It doesn’t stay put in any position like we try to make other breakbarrels do. But that’s because of the keystone breech. The breech is locked up solid then it’s closed, yet the barrel doesn’t add one ounce of resistance when cocking the gun. The action fork doesn’t have to squeeze this barrel to make the breech tight.

Trigger pull

I am flabbergasted by how light and smooth the trigger of this rifle is. Measuring it as it came from the box the first stage took 1 lb. 9 oz. and stage 2 broke at exactly 2 lbs. every time. It is so light and crisp that I didn’t want to adjust it, but this is a test, so I’m adjusting it heavier — because it’s a half-pound lighter than what Sig says is the minimum pull weight.

At first I turned the screw counter-clockwise to see if what Sig says about the trigger not going below the minimum. Or, at least that’s what I’m telling you. I won’t tell you that I turned it backwards by mistake — that would be stupid. Either way, the pull stayed at 2 lbs.

Then I adjusted it clockwise and raised the pull to 2 lbs. 7 oz. Yes — the pull weight adjustment does work.

First stage?

The first stage was adjusted the way I like it, but for the sake of this test I tried to adjust it out. And I succeeded! I gave the trigger a single-stage pull. Stage one was long and I could feel movement in the trigger blade, though there was no creep as the blade advanced.

After testing that I adjusted the trigger to exactly where I want it — a long first stage followed by a short crisp second stage. The Matchlite trigger is a marvel. You’re going to enjoy it!

Summary

This test could not have gone better! Everything I tested either worked as it had when I was at Sig or better. I just hope accuracy continues to hold where it was then, as well. Next time I will sight in the scope and give you the first groups.