LTT SCD

[WobblyPossum]

The tab in question interfaces with the FPS during the cycle of operation so that the FPS and firing pin aren't battering each other. The tab allows the FP to remain in a free-floating state during halfway point of the cycle, in the previous Gens this would allow the FP to ping-pong off the FPS thereby battering both. What would happen on high round count Glocks (Gen 1-4) is that this battering *could* allow the FPS to fail if these parts were not replaced when enough wear was present.

If you have a Gen5 simply lock the slide to the rear and you will see that you can freely move the FP, Gen 1-4 you cannot.

Learning has occurred.

[Jim Watson]

Be advised that there is a literal Chinese Copy on the market. A deal too good to be true, etc.

https://www.ebay.com/itm/17493135893...3ABFBM9re0rvRf

[Clusterfrack]

I took some measurements of a stock Gen 4 and Gen 5 backplate along with those of a Gen 1-4 SCD (Tau manufacture) and Gen 5 SCD (LTT manufacture) with a digital caliper. Hoping this will help some who are wondering if they can use a Gen 5 SCD on a Gen 1-4 Glock. Sorry for the crappy cell phone pics and if my handwriting isn't legible. Let me know if needed and I can type out the measurements or try to get some better pictures.

Attachment 86248

Outside of the obvious difference in the shape of the right side notch, what I'm seeing is that the notch on the left side of both the OEM Gen 4 backplate and on the Tau Dev Gen 1-4 SCD is slightly larger than their Gen 5 counterparts (.01" larger comparing the OEM backplates and .0135" larger comparing the SCDs). Right side notch on the Gen 5 SCD provides plenty of clearance for Gen 1-4 Glock frames.

I installed the Gen 5 SCD on a Gen 4 G19 to test fit and function/compatibility and it does work but is a little tight due to the narrower left side notch on the Gen 5 SCD. It runs into a slight clearance issue on the inside edge of the Gen 4 ejector housing and what appears as a bit of a flange on the rail (this same flange is not present on a Gen 5 ejector housing). A slight push on the gadget will push it past the flange but it will not swing back to the fully closed position freely.

Outside of the stickiness when pushing the SCD forward, function is unaffected in the sample of one that I've tried it on. Speaking only for me, if I had a Gen 1-4 gun and the lack of an SCD was preventing me from carrying it then I'd grab the LTT gadget and slightly file/sand enough material off of the ejector housing flange to make it flush with the remainder of the rail and use the gadget without concern.

One final thing that I've noticed on both of the LTT SCDs that I picked up, the flange that fits into the slot in the backplate is around .005" thicker and the hinged plate is around .003" wider. It isn't much but I've been able to tell that they're a more snug fit than my Gen 1-4 Tau Dev SCDs and exhibit less play during install/removal. Overall awesome products and I'm ecstatic that they're back on the market as I was in the boat of not switching to carrying my Gen 5 until I got a gadget back on it.

Flange on the Gen 4 ejector housing rail that causes slight interference with the Gen 5 SCD
Attachment 86250

Gen 5 SCD on Gen 4 19
Attachment 86251

Did you compare the depth of the circular recess for the firing pin spacer? This is important for retention of the SCD.

[Duckysattva]

Did you compare the depth of the circular recess for the firing pin spacer? This is important for retention of the SCD.

Good question and why I freakin’ love this place.

I don’t have a depth micrometer (and now won’t be able to sleep until I get one and can definitively answer this question with real numbers) but my eye tells me that the Gen 5 SCD recess is ever so slightly deeper than on the Gen 1-4 SCD.

Not sure of the best way to bubba the measurements in the absence of a depth or maybe some small feeler gauges. For now, I took a mechanical pencil and released the tension and pushed the lead back with the gadget to the point that the shelf on the edge of the pencil’s guide and the upper edge of the recess on the SCD met. Repeated the same method a few times on each Gen SCD and it appears to me to confirm that the Gen 5 recess is very slightly deeper, I’m betting on the order of a couple thousandths at most.

Anyone have a version of each SCD and a depth micrometer that check this?

What are the odds that one of the few folks who got the CAD drawings for the Gadget from Tau could provide dimensions of all these key points (notch widths, firing pin sleeve recess depth, flange thickness, etc.)? That would be very interesting to be able to compare the multiple generations.

[WobblyPossum]

This is all correct -- as long as you replace "the tab" with "the vertical extension added to the starboard side of the trigger mechanism housing". The tab on the frame only serves to help fill the much larger gap in the slide cover plate necessary for it to clear the new vertical extension on the trigger mechanism housing when removing the slide from the frame.

I was referring to the tab added to the frame in the Gen5 guns.

[echo5charlie]

This is all correct -- as long as you replace "the tab" with "the vertical extension added to the starboard side of the trigger mechanism housing". The tab on the frame only serves to help fill the much larger gap in the slide cover plate necessary for it to clear the new vertical extension on the trigger mechanism housing when removing the slide from the frame.

You are correct, however I misread this "...the one on the right is also to pass over the little rectangle of plastic that sticks out from the back of the frame." and presumed the question was about the "tab" I erroneously referenced.

Removing the 'frame dust tab' would accomplish nothing in this case as the slide cover plate still has to pass the vertical FPS tab I reference during the installation of the slide to frame.

[echo5charlie]

I was referring to the tab added to the frame in the Gen5 guns.

The frame tab is only to reduce the amount of 'hole' required by the Gen5 slide cover plate. Removing it would still not allow a Gen4 plate to work.

[WobblyPossum]

The frame tab is only to reduce the amount of 'hole' required by the Gen5 slide cover plate. Removing it would still not allow a Gen4 plate to work.

So my initial understanding that a Gen5 SCD will work with a Gen 1-4 gun but a Gen 1-4 SCD won’t work with a Gen5 gun is correct?

[Clusterfrack]

Good question and why I freakin’ love this place.

I don’t have a depth micrometer (and now won’t be able to sleep until I get one and can definitively answer this question with real numbers) but my eye tells me that the Gen 5 SCD recess is ever so slightly deeper than on the Gen 1-4 SCD.

Not sure of the best way to bubba the measurements in the absence of a depth or maybe some small feeler gauges. For now, I took a mechanical pencil and released the tension and pushed the lead back with the gadget to the point that the shelf on the edge of the pencil’s guide and the upper edge of the recess on the SCD met. Repeated the same method a few times on each Gen SCD and it appears to me to confirm that the Gen 5 recess is very slightly deeper, I’m betting on the order of a couple thousandths at most.

Anyone have a version of each SCD and a depth micrometer that check this?

What are the odds that one of the few folks who got the CAD drawings for the Gadget from Tau could provide dimensions of all these key points (notch widths, firing pin sleeve recess depth, flange thickness, etc.)? That would be very interesting to be able to compare the multiple generations.

I did some testing for Tom several years ago, and have some notes. Unfortunately I’m on the road for the next week.

[echo5charlie]

So my initial understanding that a Gen5 SCD will work with a Gen 1-4 gun but a Gen 1-4 SCD won’t work with a Gen5 gun is correct?

Yes and maybe no. I have installed a Gen5 Tau SCD on a Gen3 Glock in the past and the flapper would not come to proper rest. Applying a very small amount of pressure would seat it. I never did a live fire test.

That is the result of a study group of one.