TargetTalk

I just bought my first pcp airgun a Hammerli ar20. I know it’s entry level rifle but I have a ton of fun with it. So can you tell me a few things. One should I leave the cylinder charged? In the gun? Do I need to oil anything? Seems like I am getting water as it spits a couple drops on the stock after firing. I must say I am impressed as I was doing some pellet testing and was amazed at this guns ability. I think I found a pellet the gun likes how do I ensure I get pellets that shoot like this? How do you measure them? Here is my best group at 10m this is 10 shots Benchrest.

Not trying to be snarky, but your best bet is to follow whatever the manual says, rather than an internet forum (even one as great as this). :)

For example, the manual on my rifle says to loosen the air cylinder and purge the air inside the regulator between uses. However, I think I've read many here say to always leave it pressurized.

Generally I try to keep oil out of any trigger mechanism because it tends to attract crud, but others say a light oiling is good.

If you are getting water on the stock, I'd try to figure out where it's coming from. The most likely source is condensation on the outside of the air cylinder as you use up the air and it gets colder. If it's coming from anywhere else, I'd imagine there's a bigger problem.

marky-d

It is fine ( actually better) to leave the cylinder charged unless you are flying commercially then regulations require it to be discharged. It is generally recommended that the rifle itself should not be left charged when not in use so you would loosen the cylinder and discharge the air in the rifle by dry firing it.
The rifle should not produce water. You need to investigate the source of the water and eliminate it. Water will quickly damage the regulator and firing mechanism. The most common source of water is from the compressed air, how are you filling your cylinder?
You should not oil anything on an air gun, only lubricate as directed in the manual.
Pellets are produced in different sizes, eg. 4.49 and 4.50 and different weights.You select pellets by testing different lots of different sizes and weights
to find what shoots best in your rifle.