The rear of the recoil spring assembly must be positioned fully 'up' (toward the barrel) in the semicircular notch located on the front of the barrel lug during reassembly. This positions the rear of the recoil spring assembly so it can be properly located in the frame during reassembly.
When you field-strip the pistol the rear of the spring assembly is sitting 'low' in the notch, which is normal. This captures the assembly for field-stripping.
When the pistol is reassembled, however, the rear of the spring assembly must be positioned completely 'up' in the small notch ... NOT in the same 'low' position in which you found it during field-stripping.
When I attended my Glock armorer class we were warned that if someone didn't position the rear of the spring assembly completely up into the semicircular notch for reassembly that the assembly could become damaged/broken. It puts unintended, improper stress on the base of the plastic guide rod, and it could become damaged. In the single spring assemblies this can result in the rear base of the guide rod breaking off. In the subcompact dual-spring assemblies, with metal bases, the inside of the frame can become marred, scratched, gouged, etc., if the metal base of the guide rod is sitting too low in the barrel's notch during reassembly.
Sure enough, one day one of the guys had his guide rod come out the front of his G22 after he reassembled it and was hand-cycling it. The base of the rod had broken off. After I replaced the spring assembly and was talking to him, I learned that he had never bothered to properly position the rear of the assembly completely up in the barrel lug notch during reassembly. Didn't think it was important. :banghead:
Also, it's not uncommon for the bottom of the barrel to rub against the top of the recoil spring, at the rear of the spring assembly, during barrel movement (unlocking/locking). It can sometimes sound like a scrunchy, unlubricated screen door, and you can probably see a rub mark along the bottom of the barrel at some point after a while. Rubbing lubricant along the bottom of the barrel in this area, while you're lubricating the pistol after cleaning, can help reduce the friction in this area.
Of course, remember that the pistol was intended to cycle during shooting (aside from initially loading the chamber in preparation to fire) when things happen very fast, and the spring was designed for this task. Trying to duplicate the 'feel' of the functioning intended to occur at 'full speed', via hand-cycling, isn't going to yield the same results, you know. Recoil operated is not the same as 'hand operated'.
Also, I rather doubt they designed the firearms so owners/users could sit around and slowly hand-cycle the empty pistols, listening to them ...
Read the entire owner's manual. It's never a bad idea.
As an armorer I've had to resolve more functioning problems caused by insufficient or excessive lubricant than I have actual parts problems. Either extreme can have its own problems. I've never understood why some folks just seem to think that when they have a firearm and a bottle of lubricant in front of them that they're somehow inherently 'gifted' with the knowledge of how to properly lubricate the firearm. I've watched some folks very deliberately apply barely a 'fly speck' of lubricant to a gun, and then another person try to use half the bottle of oil, saturating the gun (so they don't have to worry about oiling it for the next several months
).
If you have a Glock armorer in your area, like perhaps wherever it was that you purchased the pistol, why not stop by and talk to him/her for a few minutes to learn more about your new pistol, how it functions, how it should be maintained, etc..
It pays to learn about the needs of each design and the recommendations of each manufacturer.
You can also call Glock if you want to talk to a customer service person, or maybe a technician, depending on how busy they may be at the time.
Just my thoughts.