So I'm window shopping in a local gun shop and see a compact Glock with a lower-than-normal price. It looks to be in very good shape, 98%-99%, but it's $100 cheaper than several other similar Glocks in the same display case. I peer at the tag, and the serial number looks strange; it appears to be a number, then 3 letters, then 3 numbers. So I ask to see/handle the pistol, and it all begins to get clearer.
A normal older Gen3 (flat non-LCI-extractor), in excellent condition. Frame looks positively minty, only minor exterior wear on the metal. Serial number on slide and barrel:
And serial number on the frame (normal location, under barrel and in front of trigger guard):
You might be thinking, hmmm, what's going on here; the serial numbers don't match (referring here to the added "1" at the front of the number, not the "US" which was a standard suffix on the frame serial number for many years, but has since been discontinued)?
Explanation: In 2001, Glock made a bunch of pistols that had a small problem with the metal frame rails that are embedded in the polymer frame. Some of the rails had been formed or hardened incorrectly, and after use, one of the rails would occasionally break off, often causing a stoppage and preventing further firing.
These pistols were all concentrated in the "E" series of serial numbers, such as the one pictured above. All serial numbers that began with "E" were not affected (only some of them had been built with the bad rails), but all the pistols with bad rails were in the "E" series of pistols.
Glock offered to fix (for free) any affected pistol that had a rail break, and also offered to replace the frame on any affected pistol (you had to call Glock Inc. and have them check your serial number to see if it was affected), again, for no cost. They also seriously annoyed many owners/users by terming this program an "upgrade", not a "recall", as in "We'll upgrade your pistol to one that works and shouldn't break." The response from users/owners was along the lines of "If it looks like a duck, sounds like a duck, and we see it in a duck pond..." Most folks treated it as a recall, it's just that the manufacturer never called, owners had to find out about it on their own (and most did).
Anyway, when the pistols were sent back to Glock, they would manufacture a new frame for it. However, there are strict Federal laws/rules about serial numbers only being used once on each model of any particular firearm, and so they couldn't make a new frame with the old number. If they did, even if they intended to destroy the old frame after replacement, for a short time there would be two frames for that particular pistol, both with the same serial number, and that (apparently) is a serious no-no. So Glock did the next best thing; they made a frame that included all of the original serial number, but with a number "1" added to the beginning.
In the case of the above pistol, the serial number does indeed fall into the range of guns that were caught up in the frame rail upgrade/recall. Now, that is not the only reason that a Glock can have a frame replaced at the factory. Another popular reason is because someone has blown-up the pistol, often with hand-loaded, reloaded, or even factory ammunition that was somehow defective. Sometimes the case will blow-out in a downward direction, and the high-pressure gas will damage the frame, with cracking and missing chunks of plastic being common problems under these circumstances. If the barrel and slide are inspected by the factory and cleared for re-use, the frame would be replaced (usually paid for by either the user or an ammo company) and the pistol would be returned to the owner.
Because there is no quick and easy way to know for sure WHY the frame was replaced, most folks tend to lean toward the worse-case scenario, and shy away from guns with mismatched serial numbers. For this reason, some dealers will end up pricing these guns lower, to get them to sell. I believe that is why the Glock pictured above had a significantly lower price than other similar pistols in the case, and that made it possible for me to pick it up quite reasonably in a trade. It shoots well, exactly to point-of-aim, and I am looking forward to using it regularly.
The approximate serial number range for the frame rail upgrade/recall is EGX*** through ESK***, although
you must call Glock Inc. to find out for sure if your pistol is affected by the upgrade (remember, not all pistols in this range will be affected, and there may be ones outside this range, too). As far as I know, this upgrade applied to all frames sizes and calibers.
Here is a photo showing the frame rails involved in the upgrade that break (most often the rear rails are the ones with problems; don't think I've ever seen/heard of a front rail break):
(Note: some of the information in this post was gleaned through discussions with factory personnel, some through discussions with other people like Glock/police armorers, some info was heard second- or third-hand from people that I trust, but most of it is not verifiable in any way, and that is why no sources are listed)
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