Let me start with the fit and finish.
The Stoeger X20 I received had a very nice wood stock with defined grain lines and was a bit darker than I expected with the pictures I have seen. Also it is fitted with a very nice butt pad. When I first shouldered this X20 if felt great in my arms. A very nice Monte Carlo ambi stock for the lefties...

The overall stock appearance was great Well made with finished cocking lever cutout.
The metal work is fair and equivalent to any Spanish or Chines air rifles that I have seen. There were no visible machine marks or scratches in the metal and held a uniform bluing finish from barrel to back of action. The trigger guard is plastic but the trigger itself is a copy of the Theoben triggers that most of you have seen on the early Gamo. One exception is the safety which is in the back of action instead of in front of trigger like Gamo and Crosman springer are. I have pictures to illustrate how it looks
The front an rear sights are a mix of plastic and metal. Where the main body of sights are metal and the actual sights and adjusters are plastic. I would say they are sturdy. I notice that the rear sights are mounted into the action which is metal and so is the body of the sights These will not wallow out or shake loose either..

The trigger guard is plastic but in my opinion looks very nice. It is set into the stock very nicely. To me there is more room to make adjustments to the trigger with this design of trigger guard.
My overall first impression of the aesthetics is a 9 with 10 being the highest Yes I was impressed by the overall appearance of this model Stoeger. It could almost be taken as a carbine since the barrel is so short.
Now for pre tune numbers. I cleaned the barrel and whipped the gun down. It was pretty clean and I will give Steve and Archer Air Guns credit for that. He offers a couple different preps prior to shipping guns. I took the basic one which is an inspection of the over all gun before he ships. Steve can chime in and give you the different types of services he has or just go to his web site and read about them.
I set up the chrony and picked JSB Exacts. They are around 8.3 gn I think. A bit heavier than the Gamo Hunters. The following string of numbers is really not a true given because the barrel, seal and spring was not broken in but here you go.
923, 911 920, 909 892 899, 901, 886,899, 885, 881, 878, 883, 883, 880, 880, 883, 890, 888.
I might add at this point that the trigger is exactly like the Gamo and Crosman Theoben triggers as far as being a heavy pull or squeeze. But we can fix that..
Those are the numbers and you can figure out the average and deviation if you like. I was not interested in the numbers myself since the gun was new.
Next was the tear down of the Stoeger X20. First thing I noticed was the action and articulating linkage. Very similar to what Crosman is having made in china. If I was betting man I would say these actions and linkage along with the piston came from the same factory...

When I got her all the way down for sure I thought I was looking at a Crosman Quest power plant..

These power plants have a good piston in them and most of the ones I have tuned the compression tubes have kept good tolerances. Outside of the different safety it looks just like Crosman Quest power plant for sure. I did my normal turbo tune on the Stoeger but I wanted to soften the recoil a bit. Instead of replacing the stock spring with one that was the same from JM I decided to use the Merlin XL square wire spring from JM. It is a bit softer and a bit more docile and will deliver less fps than a comparable spring.
As I mentioned above the trigger on the Stoeger weighed in at around 7 to 8 lbs on my trigger scale. And not for the BIG PLUS...

You can use the GRT-III trigger in the Stoeger X20. It is a drop in and works fantastic. The only thing that you need to do beside put the trigger in is file about thirty thousandths off the end of safety nub. I will show you in the pictures. It is just another few minutes of work and you are good to go..

After putting the Stoeger back together I slung some led to get any excessive lube out of chamber. Then ran he across the chrony once again. Now remember I replaced the new stock spring with a Merlin XL and of course an new delrin spring guide and Tesla seal so these numbers are really irreverent until a couple hundred shots have been run through her.
836, 842, 829, 820, 825,833, 830, 840, 835, 839, 831, 840, 834, 836, 841, 839, 840, 848, 837
The Merlin XL spring is not a power spring so I would imagine that after a couple hundred shots or so she will settle in around 840fps. That works for me and my paper punching. :)But I would assume if I had used the new Stoeger spring over she would of settled in the low 900 fps range.
I have taken a bunch of pictures to show all of you what the Stoeger looks like in pieces. Also you will be able to see what needs to be down in order to put the GRT-III trigger in. Really no big deal and everyone has a file...)
Oh and before I forget, the trigger scale reading with the new GRT-III trigger was right a 1 lb. Great break I love it when the trigger breaks so crisp and clean...

Here are few pictures..