The Drop-In FSSG that I have been using has worked well in terms of providing select-fire capability to my Glock 23 reliably, but I do have one issue with it, and that is in terms of ACCURACY when shooting it at full auto.
I first noticed when I saw that the spread of shots at 10 meters was quite large. The first shot would be dead on, but then the second and third shots would be way off by a couple of inches from eacch other. A rough estimate would be like this: If I aim at the bottom of the target, the first shot would hit spot on the lower right side of the abdomen, then the second would be on the chest area on the left side of the chest of the target, and finally the third shot on the left shoulder or left side of the face area of the target (see picture below).
I found this a bit strange, because the other metal FSSG that was given to me shot quite good at 10 meters (see my previous blog here). With everything else the same (i.e., same configuration, same distance, same ammo, etc.) from the pictures it looked like the metal FSSG was shooting tighter groups by about 3-4 inches.
I can't really say for sure how this came about, but my main suspect is the problem is in terms of the LOCK TIME BETWEEN SHOTS. I suspect is the issue, because when I do the Dry-Fire Test I described on another previous blog, the slide sorts of pauses a bit when it is near the end of its travel, before it goes right thru and releases the Striker.
In other words, the sword-like protrusion (which I will now start to call as the "Sear") gets a bit snagged with the Trigger Bar before proceeding thru. Now, why does it snag? I suspect that the Drop-In Sear does not have as smooth a shape when engaging the Trigger Bar. Because of this delay, it causes the lock time between shots to be just a little bit longer. Of course, the lock time is very short, measured in milliseconds, but that slight delay is enough to bring the muzzle up a little bit higher before the next round or rounds come out of the barrel. It is something like: Higher Lock Time Between Shots -> Muzzle is Pointed Higher as it Recoils -> Bullets Hit Higher.
What I have done, is to file down that sharp portion of the Sear, making it more rounded, so now the Striker is released more smoothly, and a little bit earlier during full- auto.
Another troubleshooting I made, was to remove my New York 1 Trigger Spring, and went back to the Standard Trigger Spring. My theory is that the heavier NY1 Trigger Spring affect the interplay between the Trigger Bar and the Sear. Since the Trigger Bar will have a heavier resistance against the Sear, then that affects the lock time also, making the lock time for the next shot slightly longer.
'Full-Auto Shooting Comparisons'
After making the fixes above, I took my Glock 23 on another shooting session. The full-auto shooting results showed still a large grouping, about the same as before tuning. There is a very slight improvement in that a lot more shots seem to be concentrated on the middle area compared to before.
Side-by-side comparison of the target boards used before and after tuning of the Sear and use of Standard Trigger Spring
The result is a bit disappointing, after all that work and adjustment, the improvement is only marginal. Remember that this is just at 10 meters. If the distance was at twice that range (at 20 meters), its hard to imagine hitting the target with any degree of consistency even when using bursts fire during full auto. So practical accuracy at full auto is not so good, its just mainly for fun at ranges only up to around 10 meters.
I still think the issue is with the Sear Lock Time, though. The Metal Full-Auto Only FSSG did very well, because its lock time was much faster, enabling closer shots during full auto bursts fire. The only way perhaps to improve the lock time of my Drop-In FSSG, is to smoothen the shape of its Sear. I don't know if that is even possible, because material has already been removed. Besides, I don't want to mess around with the Sear anymore. If I make a mistake, I will ruin that Sear, and lose the full-auto capability. So for now, I think I will just leave things as it is.
Side-by-side comparison of the target boards using the Metal Full-Auto Only Sear, and the Drop-In Select Fire Sear
I finally was able to take a video of me shooting the Glock 23 in full auto, here is the video:
http://youtu.be/tV37hTEqYCk
(End of Part Four)
--> Glock 23 Machine Pistol Configuration Part One
--> Glock 23 Machine Pistol Configuration Part Two
--> Glock 23 Machine Pistol Configuration Part Three
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