One of the most reliable firearms you can decide to buy is a police/LE trade-in or used Glock, if you know what to look for. When looking at one of these used Glocks there are important things you need to look for and replace, if you purchase one.  In this article, I will breakdown some of the key things to look for and avoid, as well as the critical parts that must be replaced after your purchase. A gun store will not let you strip the gun completely down to its small internal parts so you have to understand what to look for, to insure you are getting what you want. This will cover only Gen2 and some Gen3 Glocks, there is a reason for that, and you will see why as we go along.

Gen3 G22 & Gen2 G19

Advantages:

First let’s talk about the advantages of buying a police trade-in or used Glock. When you understand what to look for in a used Gen2 or Gen3 Glock, you know you are buying the most reliable and longest serving generations of the Glock design. You are avoiding the sometimes problematic issues with the newer Gen3 and Gen4 designs and you are hopefully spending a lot less on the firearm.  On average you can get the trade-in /used Gocks in the Low to Mid-300 dollar range. I recently helped a co-worker select an excellent condition LE trade-in G23. He spent $314.00 on the firearm, I put in $20.00 worth of parts and it was good to go.  Another huge advantage and one of the main reasons to buy the older Glocks, is no MIM parts. The Gen2 and select Gen3 Glocks have investment cast /machine tool steel locking blocks, extractors and firing pins. You are getting a more robustly built Glock, with higher quality parts in those key areas, vs. the newer Glocks.

Serial Numbers:

You must pay close attention to serial numbers when looking at used Glocks. This will serve several purposes, unique to a Gen2 or Gen3 Glock.  The serial number will help you identify the approximate date of manufacturer and what to look for, depending on it being a Gen2 or Gen3 gun. Look to see if the Serial numbers on the Slide, Frame and Barrel match. If the serial numbers on any three of these only contain numbers, then they have been replace or are aftermarket if they are not OEM Glock.

GEN2 GLOCKS:

Gen2 guns have had several mandatory part changes and upgrades, depending on the approximate date of manufacturer. This will also help you understand how old the firearm is. All Gen2 guns will have the tool steel parts we have already talked about, unless someone changed them out.  In the 2002 Glock armorers guide, replacement of the old slide lock spring to the upgraded slide lock spring is recommended. All Gen2 guns will need this part upgraded.  Some Gen2 guns that have a black trigger bar will need the Six-Part upgrade.  Serial Numbers starting from AA through SL (depending on model) may need this upgrade, if not already done. (see Six-Part Upgrade: below for more information) If you stay in the three letter serial number range starting at (AAA###) and up, you should be ok as far as the Six-Part upgrade is concerned.

GEN3 GLOCKS:

With the Gen3 guns, you want to look at the serial number closely to make sure it was made before Early to Mid-2009. As long as you are under serial number range (MSZ###) or do not have the dip extractor you are probably ok as far as MIM parts.  Sometime in Early to Mid-2009, Glock started using the MIM locking blocks, extractors and firing pins. There may be some mixed MIM/non-MIM parts in the (M) serial number range, so be aware of that. The only required upgrade/replacement part in pre-2002 Gen3’s, is the replacement of the old slide lock spring to the upgraded slide lock spring, as mention above.  2002-2009 Gen3 guns will not require any part upgrades. important to note: if the serial number on the frame starts in the (EAK### through EVR###) range, the rear slide rails are prone to breakage. Glock recommends those frames be sent in for replacement.

Gen2 Extractor / Old Gen3 Extractor / Dip (MIM) Extractor

Wear:

There are some key areas of wear that you can look for, on trade-in /used Glocks. This will help you identify if the firearm has been used excessively or minimally, depending on caliber. Your .40 cal and .357 sig Glock will show more wear in these areas than a 9mm or 45ACP will, due to them being harder on the firearm.  Add all of these indicators up to make a decision on how used you think the firearm is. It will really help if you ask the gun shop, if you can removed the slide (field Strip) the firearm, to inspect the gun. I do not buy any used firearms unless I am able to do this. Bellow are examples of normal wear on 9mm and .40 cal Glocks, nothing extremely heavy.

1. Barrel Wear Areas

Barrel chatter marks will be visible on the outside of the barrel. The top of the barrel chamber will also have wear marks where it makes contact with the top of the slide. The stronger / more pronounced the wear in these areas will indicate use.

Barrel Wear G22 / G19 & G22 barrels / Slide Barrel Wear

2. Slide Wear Areas

The outside slide condition will indicate carry use. The inside of the slide will show wear in two particular areas. The inside top of the slide will indicate wear, where the top of the barrel makes contact with the slide as it reciprocates and on the slide rails on each side of the barrel chamber.  Heavy peening wear on the slide rails slightly in front of the barrel chamber area indicates heavy use.

Slide Rail peening G19 / Inside Slide Wear Gen2 G19 / Inside Slide Wear Gen3 G22

3. Frame Wear

You want to look at the frame carefully to inspect it for cracks or any major damage. While the frame is polymer (plastic), wear on the outside of the frame is not an indicator of firing use, only carry use. A lot of the LE trade-in guns are carried more than shot.

In the picture below; a G19, (SN# FKF 826), date from 2003, has a cracked dust cover.  I purchased this pistol for 334.00 dollars out the door.  I did not notice the crack at the time of purchase, but when I got home and did a detailed strip and inspection, I noticed the crack.  I remembered there was another G19 at the store with an FKF serial number, so I returned the next day with the cracked frame Glock. Luckily for me, this store was a Glock LE distributor and traded the firearm, no questions asked.  Make sure you check the frame areas very carefully, as some stores will not let you bring the firearm back.

Dust Cover Frame Crack on SN#  (FKF 826) G19

Replacement Part Recommendations:

After selecting the used Glock and purchasing it using the information above, I would recommend purchasing an OEM Glock Spring Kit and have it installed. This serves two purposes. (1) If you have a Gen2 or Gen3 with the old slide lock spring, it is in the kit. (2) The spring kit replaces all six of the springs in the firearm and will insure that all springs are fresh as true round count will be unknown. Replacing the main recoil spring is also a good idea when round count is unknown. Since the main recoil spring and slide lock spring are in the kit, this is the best purchase as it will only cost you around $20.00 dollars. Most Glock parts are very inexpensive, if you identify any weird after market parts you are not sure about, replace them.

Spring Kit / Old Slide Lock Spring / New Slide Lock Spring

Trigger Springs (NY1) & (NY2):

Some Police/LE trade-in Glocks might have New York (NY) NY1 or NY2 Trigger Springs in them. A NY1 spring will be OD green and a NY2 spring will be Orange.  Bellow: The black frame on the left, has a NY1 OD green spring in it and the OD frame on the right, has a stock 5.5 lbs spring. If you have one of the NY Trigger Springs, your trigger pull will be heavier than the stock 5.5 lbs spring. You will probably want to removed the NY’s and replace it with the 5.5 lbs spring. If the Glock has a NY1 spring and the trigger pull is relatively smooth and easy to pull, it probably has an OEM (-) Connector. This is a popular combination with LE Glocks.

      Connectors:

Now, you wont be able to see if the Connector is a (-), standard or (+) Connector, without stripping the Trigger Mechanism down, and the store is not going to let you do this. If you see the Glock has a NY1 Trigger Spring and the trigger pull is excessively hard/heavy to pull, it probably has a standard or (+) Connector.  You will have to decide if you want to spend the approximately 20.00 dollars to replace or experiment with there combination.  Note: I prefer a NY1 with (-) Connector combination in my Glocks.

(left) Black Frame with OD NY1 trigger spring (right) Green Frame with 5.5lbs Spring
(-) Connector & OD NY1 Trigger Spring

.40 Caliber Gen2 Glocks:

If you are buying an early Gen2 .40 caliber Glock, usually pre 1995, you will need to be on the lookout for the 4340 ejector.  The 4340 ejector was replaced with the 1882 ejector. Some confuse the 4340 ejector as a broken ejector, due to its short appearance.  The 4340 ejector was replaced, as it puts unnecessary stress on the extractor and due to late ejection can cause case deformation and crimping. This can also cause stove pipe issues.  Over time the use of the 4340 ejector can cause the extractor to break. If you find a .40 cal Glock with a 4340 ejector, you may want to pass on it. If you buy a Glock with the 4340 ejector, replace it with a new Trigger Mechanism Housing with the 1882 ejector.

4340 ejector & 1882 ejector

Six-Part Upgrade:

It is important to note this upgrade is extremely rare to come across, as it was identified over 20 years ago. Some  Gen1 ‘s and early Gen2’s may require the Glock Six-Part upgrade as mention above. If you identify the Glock is one that needs this upgrade, I would suggest passing on that particular Glock as replacing the firing pin and extractor with new MIM parts would defeat one of the main reasons of getting the older/used Glock. If you are looking at a trade-in /used gun, you can easily pull the slide back and look at the trigger bar. If it is solid black and not just dirty from use, it will need the upgrade. This consists of replacing the (trigger bar, firing pin, firing pin safety & spring, extractor and spring-load bearing).

(Top / Right-Side of Frame) Silver Trigger Bar, no upgrade needed

Conclusion / Final Thoughts:

Most police/LE trade-in Glocks have been maintained by a department armorer and will probably have the upgraded parts already in them, from years ago. Used Glocks that where in private hands, will more than likely be the ones that need minor part replacement here and there. I have purchased several LE trade-in /used Glocks. Two of my main personal defensive firearms are a late Gen2 G19 and an early Gen3 G22. These have been my go to Glocks and I prefer the quality of the older Glocks compared to the new offerings. Glock does not care if you are the original owner.
They have a lifetime guarantee and if you ever have a problem, simply call them and they will take care of it on their dime.
I will put a few links to serial numbers, they change from time to time, so if one does not work you can go to the next. Information on Glock serial numbers can be found here: (Glock Talk Serial Number Project),  (Glock Talk Serial Number current Updates),  as long as they stay up. 
If you remember to look for the key things talked about here, you will be walking away with a excellent Glock, that will be very dependable and reliable for years to come.

Duncan

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