The 21 appears to have a factory spring. I'm not sure on the 19 to be honest. It's not captive like the 21, and as I understand the 21 came with a captive single spring and the 19 came with a single spring (non captive).
The second generation Glock 19s switched to a captive recoil spring in 1991 (I believe). You probably can get Glock to send a recoil spring for free if you give them a call.
If you are not already aware, you should know about the "upgrades" Glock issued over the years for the 19. If you do a search for these you'll find more information on them.
1990 Upgrade
Glock Model 19, 9mm Luger caliber, requires an upgrade for the following serial numbers:
AN, BP, BR, BV, BW, BX, DL, DM, DN, DP, DR, DS, DT, DV, DW, DX, DY, DZ
These pistols may have the potential of the action to malfunction as follows:
1. The slide locking back on a full magazine.
2. Failure to lock into battery because the barrel lug drags on the slide lock.
3. The magazine follower tips or sticks in the magazine tube.
1992, 6 part Upgrade
GLOCK, INC. Technical Bulletin #920403
April 1, 1992
Glock, Inc. announces a production change of the firing pin safety system. This new firing pin safety system has been installed in all production Glock pistols since November, 1991. A voluntary upgrade is being offered to maintain the Glock tradition of ensuring that all of our pistoils are up to the latest standards in 21st century Goock technology.
Most importantly, the components of the new firing pin safety system are not interchangable with the components of the old systam and Glock will always strive towards maintaining this feature of interchangability while working to ensure future interchangability.
The upgraded firing pin safety system consists of: the firing pin, firing pin safety, the extractor, the spring loaded bearing and the trigger bar. The upgraded system is applicable only to Glock pistols with the following serial number ranges :
Glock 17 - alpha prefix AA - WF
Glock 21 - alpha prefixes through XL
Glock 19 - alpha prefixes through WJ Glock 22 - alpha prefixes through YA
Glock 20 - alpha prefixes thorugh WW Glock 23 - alpha prefixes through SK
The upgraded firing pin safety has a new surface finish making it nearly 100% saltwater corrosion resistant. Also, after rigorous and extensive testing, the new system proves to be more durable and has a longer useful life. Here, as alwyas, Glock is working toward maintianing its standard of perfection.
1993, G19 Upgrade
Glock Model 19, 9mm Luger caliber, requires an upgrade for all pistols.
These pistols have the potential for an UNINTENTIONAL DISCHARGE of a cartridge with the action open.
The Glock model 19 pistol slide has a bottom protrusion, whose function is to push cartridges from the top of the magazine into the chamber. When the pistol is jammed in a double feed situation, the slide protrusion can come in contact with the primer of the jammed cartridge and cause UNINTENTIONAL DISCHARGE while the action is open.
