by Tom Gaylord
Writing as B.B. Pelletier

Sig ASP20
Sig ASP20 breakbarrel rifle.

Part 1
Part 2
Part 3
Part 4
Part 5

This report covers:

  • Air Arms domes
  • A different rest
  • The artillery hold
  • Screamer!
  • Another pellet
  • Final group — confirmation
  • Summary

In the last report I cleaned the barrel of the Sig ASP20 breakbarrel rifle and showed you there are no real baffles to worry about. Today I want to test the rifle to see whether cleaning has changed the accuracy in any way. I also want to test the rifle resting directly on a sandbag versus using the artillery hold. I will also try some different pellets, to see if there is more potential accuracy. It should be a good test, so let’s get started.

I’m shooting 5-shot groups today because I’m still learning things about the airgun. Five-shot groups allow me to test more things.

Air Arms domes

In Part 4 the most accurate pellet at 25 yards was the 16-grain dome from Air Arms. So that was the one I wanted to try today. But I had just cleaned the barrel, which can make a gun less accurate for the first few shots. Let’s see what happened.

The first five shots at 25 yards were shot with the rifle resting on the sandbag. The front of the triggerguard was touching the rear of the bag. Shot one went to 9 o’clock in the white and shot two went to 12 — also in the white. Shots 3, 4 and 5 are all together near the center of the bullseye and look like 2 shots rather than 3. The lower hole has two pellets through it. This group measures 0.815-inches between centers and is nearly twice the size of the group I shot at 25 yards with the same pellet in Part 4. That one was five in 0.412-inches with the rifle rested the same way.

Sig ASP20 AA group 1
The first group of Air Arms domes after cleaning looked like this. I marked the shots so you can see what I saw as they were fired. Five shots are in 0.815-inches at 25 yards.

I knew the rifle would settle down after a few shots and it looked like it already had. So I shot a second group with the same pellet and same rest. This time 5 pellets made a 0.51-inch group. That’s a lot better, but still not as good as the group I shot in Part 4. It is close enough to that group for me to to say that cleaning the barrel has made no impact on the accuracy.

Sig ASP20 AA group 2
The second group of Air Arms domes shot in the same way measures 0.51-inches between centers. This is a better group and it shows that the rifle has settled down.

A different rest

I wondered if resting the rifle more forward on the bag might make any difference, so I tried that next. This time the forearm was resting on the bag and it made a big difference! Five shots now went into 0.335-inches at 25 yards. This is a very good group! It’s getting into the neighborhood of what can be done with a good PCP.

Sig ASP20 AA group 3
When the forearm of the rifle was rested on the sandbag, five Air Arms pellets went into a 0.335-inch group at 25 yards. This is getting good!

I want to point out that by changing the way the rifle is rested we cannot make any claims that cleaning the barrel contributed to this increase in accuracy. It might have been just as possible to get this result before cleaning the barrel, if the same rest had been used.

The artillery hold

Okay, this is the test I really wanted to do. Would the artillery hold do anything to the accuracy of this rifle? While I was shooting at Sig I didn’t think the artillery hold was as good as resting directly on the bag, but now I have the time to test a lot more things under controlled conditions. For instance, I guessed that holding my off hand farther forward would help.


Since moving the rifle forward on the sandbag seemed to help, that was where I rested it on my off hand for this test. Five shots using an artillery hold with the forward part of the forearm resting on my off hand went into a group measuring 0.072-inches between centers at 25 yards. I believe that is the smallest group I have ever shot with any airgun at 25 yards. It may be larger than what I have measured — groups shot with domes are difficult to measure exactly, but my best estimate puts the calipers at 0.295-inches across the widest point of the 5-shot group. Subtract 0.223-inches for one pellet diameter and you get the group size, center-to-center. This qualifies as a screamer — the greatest 25-yard screamer I have ever shot in my life with a pellet gun! Was it luck? Probably a little. But with the ASP20 it’s easy to get lucky.

Sig ASP20 AA group 4
Five Air Arms domes seem to have gone into a 25-yard group that measures 0.072-inches between centers! I pulled out the three-cent piece for comparison but also used the dime because we are getting many new subscribers and readers each day who aren’t familiar with the smaller silver coin.

Another pellet

Okay, I didn’t measure that last group until I had taken the pictures and started writing this report, so I wasn’t shook up yet. I thought it would be nice to try a pellet I had not shot in the ASP20 yet, so I pulled out a tin of JSB Exact Jumbo Heavy domes. These 18.1-grain pellets are often the most accurate — especially in PCPs.

In the ASP20 this pellet dropped one inch below my aim point at 25 yards, which was the center of the bullseye that’s above the group you see in the picture. Remember also that I had sighted the rifle in at 10 meters and only adjusted the scope according to the known distance to the target. What I’m saying is that the scope is what centered the Air Arms pellets in the bullseye — I did not adjust it after 10 meters, except to adjust the vertical knob for the new distance of 25 yards.

Ed Schultz had told me the rifle likes pellets in the 14.5- to 16-grain range and this one was two grains heavier than that. I just wanted to see how it would do. Now that I knew the artillery hold was best for the rifle I held it that way to shoot this group.

Five of these heavier pellets went into a group that measures 0.421-inches between centers. That’s good, but in light of what the Air Arms pellet is doing, I think I will stick with it.

Sig ASP20 JSB group
Five JSB Extra Jumbo Heavy pellets went into 0.421-inches at 25 yards. The group is about an inch below the aim point.

Final group — confirmation

After shooting that extremely small group with the artillery hold, I had to give the bag rest one more try. Was I trying harder now and aiming better? I rested the forearm on the bag which we learned is the best way to rest it and I fired 5 careful shots with the Air Arms domes. This time 5 went into a group measuring 0.429-inches between centers. Earlier I had put 5 into 0.335-inches with the same rest. I have to say that this is a good way to shoot the rifle and this pellet is a very good one in the rifle, but it looks like the artillery hold wins. More testing will be required to establish this, of course, and that’s why they pay me the big bucks!

Sig ASP20 AA group 5
A second group of five Air Arms domes with the forearm rested on the bag is only slightly larger than the first. It measures 0.429-inches between centers.


Let’s see, what can I say? How about WOW? I’m 71 years old and well past my prime, yet today I shot the smallest 5-shot group of my life with an air rifle at 25 yards. Bully for me, but don’tcha think the rifle had something to do with it? I do.

The ASP20 continues to amaze me. The trigger is a peach. The rifle doesn’t vibrate. The scope is clear and sharp. And the accuracy… well — you know.