Inspecting Your Work

Several months ago I took in a Glock Gen4 Model G19 with an MOS (Modular Optic System) slide for an aftermarket trigger and spring kit installation upgrade. During disassembly of the MOS slide to reach the firing pin, I quickly found that the extractor detent rod and spring assembly wouldn’t withdraw as it was locked into the slide.

Removal of the MOS plate and both screws revealed that the plate had been installed with the long screw on the extractor side, a common mistake by Glock enthusiasts if not paying attention to the instructions. The screws were simply reversed and the aftermarket kits were subsequently inspected, installed, and dressed until the pistol worked smoothly and had a nice lockup and newly reduced trigger pull. Fast forward to the present date.

I took in what appeared to be another Glock G19 from the same customer for what he stated was a serious problem. During the initial telephone call he relayed to me that the gun at first shot well after I had done the work but then starting locking up and that the trigger would not reset after firing. He went on to say that sometimes the slide would lock fully to the rear during firing even with ammo still in the magazine. Other times it would stovepipe and/or jam.

My initial thought was somehow the earlier installation did not go as I had planned. I was no doubt curious about what had gone wrong. In my mind, I could not understand what had gone wrong and I was Be thorough in inspecting and documenting any work that you do. surprised at some of the answers to those questions that I ultimately found. When I received the pistol from him this time it looked different.

Back in the shop, I noticed that although the serial number on the frame matched that of the pistol I had previously worked on, it looked different somehow. I checked my records and then realized that the slide and barrel were different. Not only had the slide been finished with Cerokote, the gun now sported an aftermarket threaded barrel with a compensator attached. At first, I thought the slide was not from the same pistol that I had worked on previously.

After removing the compensator and slide assembly, I then noticed that it was sporting anew (different brand) trigger and sear block kit. All of this brought up more questions that I needed answers to. Going into a gun that has totally changed since the last time I had it made it very important for me to contact the owner and see if he could tell me about all of the changes that had been made. Trying not to offend, I began with a casual, "What type of ammunition were you using when the

problems began?" I figured I would start there even though I didn’t think that was the issue at all. But one never knows. Especially since the pistol was sporting anew compensator and it could have been that subsonic loads were used, which can create short stroking.

After he confirmed that he used standard 9mm ball ammunition, I went on to the really important questions of when was the barrel changed out, when was the trigger changed out, when was the compensator added, and whether or not he did the work/installations himself? He quickly stated that he had decided to put another aftermarket trigger in the pistol because he had that brand in one of his other Glock 19s.

And that he liked the threaded barrel and decided to order one and since it was threaded, he decided on getting the compensator. After all, "everybody is doing it—just check out the Internet." Now that I had most of my questions answered, I knew I would be starting all over on the pistol in order to try and ascertain what was creating the problem(s) he had while firing or the issues that he had relayed to me.

He had told me that the gun would not lock up after firing and that he would have to pull the slide to the rear by hand to get the sear to lock up so that he could fire it. I began by function testing the pistol just to see what it was, or was not, doing. The very first issue that I found was that the newly installed and threaded compensator was loose on the barrel muzzle and that the slide had a heavy "sticking point" when first trying to work it rearward.

One item found was that the loose compensator could turn just enough to pinch the barrel at the front of the slide and would cause the slide to be very difficult to pull back but only at first. So, I removed the already-loose compensator and started function testing again, sans compensator. The slide was still hard to get started to pull to the rear but after a certain point, it would break free and slide back fine.

The "lock up" or trigger reset issue he had told me about was not found during these tests as the trigger was resetting each and every time as was the sear engagement. So I was not sure what he had been seeing or feeling when he worked the slide. Moving on, I removed the recoil operating rod assembly and then tested the slide again without it in place. And, again, the heavy (though not as much) sticking when first pulling the slide to the rear was still there.

I removed the slide and checked the barrel fit in the slide and there I found excess Cerokote material inside of the slide where the barrel locks up into the slide locking lug area. I also found the Cerokote material clogging (for lack of a better term) the firing pin block hole, among other areas that had the heavy build-up. My assumption here is that he had sent out the slide for the Cerokoting and then simply replaced it on the frame when it came back.

Knowing I had this issue to address now, I continued looking for other issues. I closely inspected the trigger kit, connector, springs, and everything looked to be OK other than this was not the same trigger kit, by brand, that I had installed previously. I did see some grind marks and burrs on the trigger bar where the upward protruding stem lifts the firing pin block up so that the firing pin can move fully forward when firing.

I also noticed that the protruding "tooth" on the top rear of the right side frame rail (polymer tooth) was buggered up and in need of a light filing to smooth and clean it up. I went ahead and removed the trigger assembly and sear block just to make certain I had inspected everything and found that the connector had not been correctly fitted to the sear block. This is another common issue with Glock enthusiasts (or that I have encountered anyway.) Everything from that point on appeared to be in good shape.

So I began the reassembly, one part at a time, while working them to make sure they operated properly and had no burrs or other abnormal issues. Once the "tooth" was dressed and smooth, the connector was fitted for proper operation and then the trigger bar stem was stoned, carefully reshaped, and smoothed out. Whether or not my customer ground on the stem, I may never know.

That said, I have never seen a trigger bar with this issue from any of the aftermarket trigger manufacturers, until now, therefore, I have to assume that it did not come from the manufacturer in that condition. Had he brought the gun to me for the installation(s) I could have found that issue (and any others) and addressed it with the manufacturer, at least if it was actually caused by them. And that leads me to a point here.

Often, I will hear customers or folks say that drop-in triggers only take a few minutes to do. Or, that you don’t need a gunsmith to do it because you can watch it being done in videos online. And I agree with both of those statements or assumptions; however, not in their

entirety. Certainly, it can take only a few minutes to install a drop-in aftermarket trigger—if you just pull it out of the carton and replace your trigger/sear block assembly. And it will more than likely just drop in, but consider this: Have you ever purchased a food product or any other product that came right off the shelf, or from a factory, and was either already spoiled, had glass or metal chips in it, arrived to you in the mail missing parts, or was improperly assembled at the factory? Yeah, me too.

And so this can happen with drop-in triggers or other parts. Not often, mind you, but when pulling the trigger on an explosive device, you really want to be sure it will work properly. In this case, I doubt that the ground portion of the trigger bar stem was an error from the factory. Nevertheless, you need to inspect these parts when they arrive or during installation. Moving on, I reassembled the trigger and sear block assembly and completed the assembly of the frame.

A quick check of the operating system went very well with no sticking moving parts or unusual trigger pull and sear release issues. It would lock up just fine. This had not changed from the beginning of the job as the gun was locking up for me just fine when first bench tested. The only time it would not was when the compensator would turn in such away as to pinch the barrel against the front of the slide when trying to pull the slide rearward.

With the frame assembled, inspected and ready to go, I turned my attention to the slide. Yes, I fully disassembled the slide and removed the MOS plate just to be sure it was installed properly with the correct screws being in the correct locations (again). The reason I disassembled the entire slide was to ascertain if the Cerokote build up had made its way into the firing pin tunnel, extractor seat area, and for sure, I had to clean out the build up around the firing pin block hole that I had seen.

After some light abrasive work to clean up those internal areas, I found that the extractor seat had quite a bit of build up in that area and cleaned that up. Next, I test fitted the barrel to the slide (lockup) and found that someone had dressed the locking lug area on the slide to an extent, but not enough. The center area was free from excess Cerokoting material but both corners had heavy build up still in place.

I worked this area with a stone until the barrel would "click" into place when seated and locked and so that the full width of the barrel lug came into full contact with the slide lug opening. This area is what caused the slide to be stuck or so difficult to pull rearward at first when it came into the shop. The Cerokote was preventing the barrel locking lug from seating fully into the slide, and under spring pressure would compress the barrel locking lug into the Cerokote finish.

With the barrel now seating into the slide as it should, I went ahead and checked the front sight screw just on the chance that it wasn’t secure. Remember, I can only assume that the customer reassembled the slide upon receipt from the Cerokote job, if he indeed sent the slide out for the service. The screw was tight however, and with all areas inspected and cleaned up where needed, the slide assembly was reassembled.

Before re-installing the compensator, I reassembled the pistol without it and began all function and safety checks. The slide no longer stuck (at all) when pulling it rearward, the sear was engaging each time the slide was worked, and the trigger was smooth and working properly. It passed all function and safety checks, even the firing pin strike tests. I inserted the magazine he had provided with the pistol and it worked as it should.

In other words, the slide lock was operational when pulling the slide to the rear with no ammo in the magazine. I then loaded 16 rounds of 9mm dummy ammo into the magazine and began feeding them manually to see how they fed, chambered, extracted, and ejected. No issues were found or noted. With the gun now functioning properly, I decided to install the compensator just to see how it fit up with the barrel muzzle and end of the slide.

The assembly was straight forward and the pistol function testing went well until the compensator was loosened as it was when I received the pistol. When slightly turned, the compensator would pinch the barrel when first pulling the slide rearward. Not permanently, but enough to see that the compensator would pinch the barrel muzzle against the barrel hole at the front of the slide. But when the compensator was turned back to where it should be, the action worked fine.

I had asked the customer when I first spoke with him (one of those many questions I had) if he had used any thread locker product(s) that either came with the compensator or was purchased afterwards and he told me that he had not. So, based on what I found, it needs to be used so that the compensator does not become loose when firing. And rather than do that now, I opted to range test the pistol first without the compensator.

This was so I could see how the pistol worked without it installed just in case I had overlooked something. The main goal being was to determine if the pistol would fire as it should, without any or all of the issues my customer had relayed to me previously. At the range, the pistol fed three full magazines of ammunition without any issues or previously reported problems. The pistol cycled perfectly, with no jams or other issues.

I then installed the compensator and fired three more magazines full of ammunition; and

again, no issues were noted. Obviously the problems, all of them, were solved. Back at the shop, the pistol was given one final cleaning and the compensator was installed according to manufacturer’s instructions. The use of thread locker should hold the compensator in the correct position now but I also left instructions for my customer to always keep an eye on it just to be sure that it doesn’t spin during heavy shooting outings.

Now that I have covered all of that, it leads me to where I wanted to go from the beginning. This job came in after I had done work on the pistol a few months earlier, and based on the initial description by my customer, it sounded like the work that I did for him fell apart. And until I took the gun in to inspect for myself, I quite honestly thought the same thing. However, I quickly found that the pistol that I had worked on was not the same gun at all, really.

It is my shop practice to document all of the work that I do on each and every job taken in, and often, digital photographs are taken of that job along with "notable" pictures of areas of concern, previous damages or of just the areas that I performed the work on. Thank goodness that was the case here. Even if I had never worked on that pistol before, one really never knows what one is taking in at any time.

At a time when "drop in" is the "in thing" and more and more firearms than ever before are being manufactured to accept aftermarket goodies, the gunsmith (and even the customer buying a used firearm), needs to look at them closer than ever before.

Just like AR platform guns or the 1911 series pistols, I always begin by finding out if the firearm left the factory exactly as it appeared in my shop that day, or if it was a build gun, regardless of who built it; The good news here is that you can contact the firearm manufacturer and they will tell you if the firearm you are inquiring about left the factory assembled completely as a firearm, as a frame only, or any other variation. And, they will tell you if they sold the frame only, and to whom it was sold.

They are very accommodating and reasonably quick these days with their responses. Pertaining to, let’s say, a Glock, you can contact them and give them all of the numbers on the gun (frame, slide, etc.) in addition to the serial number and they can tell you if it left the factory as a fully functional firearm or if you have a build or semi-build gun. I think that is a good practice to do, especially as the platform guns continue to roll out.

In this case, I actually checked with Glock to ensure that the slide was the same one that originally came with the pistol when it was sold by them and it did. I realize that this can be time consuming but a little homework can save you many headaches when taking in a platform gun or firearms made from drop-in parts, as you can get a clearer starting point as to what it was when it was born and where to begin your inspection/assessment.

In closing, I want to add that I have no issues with platform or drop-in kit-type firearms manufactured. If it came across that way, I meant no disrespect. Firearms manufacturers have to stay alert to consumer trends and sales (what sells and what doesn’t) just to survive these days of stamped or fully machined parts and firearms that need little or no human hands to assemble them.

Accordingly, you really need to be sure about what lands on your bench so that you can protect an unsuspecting new owner of a used firearm from costly repairs, or worse, improperly installed and fitted parts and accessories that could cause injury or death. Just remember that the firearm that had drop-in parts "dropped in" and dropped in incorrectly, now becomes your shop liability when you take it in and perform any type of repairs on it. And that is why I keep detailed notes of each repair performed.

In fact, I record every identifying component serial number with that firearm repair so that I have it just in case. I want (am trying) to protect myself and my business from someone that comes in with a build gun, has me deep clean it, or simply install an accessory or part, only to later claim that the work that I performed caused his or her firearm malfunction or injury.

If I only install a scope and bore sight a rifle in the shop and it goes fullauto on the customer or some other major malfunction not related to the installation of the scope occurs, then I want to have that information available when the attorneys come knocking on the door claiming I did something wrong that caused the issue or incident. Finally, the good news here was that all issues associated with this Glock were reversible.

You will also notice that I did not accompany this article with photographs of the firearm and parts in question only because the intent of this was not to frame aftermarket drop-in parts and accessories negatively. It was about the sum of accessorizing a firearm with many different aftermarket parts and accessories, and can lead to disappointing results if not carefully installed and fully tested.

Therefore, I intentionally did not include the specific names of any parts or accessories used in this case, nor did I photograph any of those parts to protect the manufacturer’s product lines because none of this was the fault of any manufacturer here. Just stay alert out there and make sure that you know what you have in front of you before working on it. A drop-in part here and an accessory there, over time and different gun owners, can create a myriad of issues you will ultimately have to sort through. AG