View Full Version : Recommendations on the mods for Gen 4

Bearbait in NM
01-30-2016, 11:41 AM
Sitting here looking at the various pieces, to mod for my Gen4 41. The ribs on the inside of the grip do not appear to add any "connectivity" with the back strap inserts, as the inserts only catch the lip of the grip at the bottom. And fortunately, my 41 fits best with no back straps. It appears that the channel ribs add only compressional rigidity to the frame, for the backstrap inserts?

So my options would be to mill this channel out of the grip, then mod the endo. Or more complicated but doable would be to leave the channel, and take more time and remove more material from the endo, creating a slot on the endo, to correspond with the frame channel. My first instinct points me to removing less material from the endo, as this point of connectivity seems like the weakest link. But the endo modified for the channel might provide better "twisting" support?

Any thoughts?



Edit: Went ahead and tried milling the endo, by cutting the endo shape to match up with the Gen 4 channel inside the grip frame. Decided to try the old "work on the cheapest part" concept. It weakened the rib at the pin hole, and I managed to crack the insertion nub, while installing and removing, for fit. The endo material is actually very easy to work with. My suggestion, based on a sample of one, remove the channel on the inside of the frame, if you want to fit it to a gen 4. Off to try the next test, whether Accra Glass will adhere to the endo material........

Bearbait in NM
02-05-2016, 10:18 AM
The Accra Glass did not adhere to the endo plastic, at all. Even with scuffing up the surface. First attempt was a failure.

OK, got the replace modded to my 41 Gen 4 last night. Thought I would post more observations.

I am pretty handy with this type of modding, and on a scale of 1-10, would say it is about a 5, to try and get it reasonably correct. For the second attempt, I went ahead an milled the ribs down on the inside of my grip hollow. The more material you leave on these ribs, the more material you will have to remove from the endo stub. I left about 10 thou on my ribs. I used a 1/4 round mill bastard file that has a width and arc/circumference that matches up with the inside of my grip frame hollow, reasonably well. It still took a long time to file the ribs down.

If you attempt this, you will find that in order to get the endo as deep in the frame as intended, you would have to remove a lot of material right at the base of the stub. This would also place the pin hole on the endo deeper in the frame, than the existing hole in the gun grip frame. I stopped removing material from the base of the endo stub, when the pin hole of the endo aligned with the stock grip frame hole. This gets the top of the endo interface with the tang of the gun frame close, but not perfect. I filed a square inlet at the top that corresponds to the tab in the frame that is used by the Glock grip adapters. The top interface seems stable, but I will not know until I test fire it tomorrow. A lot.

The other issue that arises when not fitting for full insertion into the grip hollow is that the locking pin could be pushed in deep enough to bind the magazine. I'll install an o-ring on the pin for now, until I decide whether or not I need to go for the deeper stub fit. If I go with the deeper fit, then I need to find an epoxy that will bind to the endo material, to reinforce the stub, by making the profile shape into a half moon, rather than a "T". That, and/or drill a hole into the stub from the bottom, and glue in a metal reinforcing rod. And if drilling a new hole location in the endo to match the G4 frame hole will likely mean that the old endo hole needs to be filled, for strength.

Fitting this to a G4 certainly entails removing a lot of material from the endo stub, no matter how you approach it. And the pin hole in the endo is the weak spot, as you might guess.



Edit: I'll see what I can do about some pictures, after shooting it this weekend

02-05-2016, 03:40 PM
It would be great if you posted a picture marked up with what you had to remove from the stub on the endo.

Bearbait in NM
02-05-2016, 06:13 PM
I'll see what I can do when I get some time. I want to shoot it to make sure it is going to work. Someone sent me some kind of IM or something asking, but I am new to the site, so it got deleted. I think I have a photo hosting site somewhere, if I can find it.

I know lame,


Bearbait in NM
02-06-2016, 03:04 PM
Ok, here is my mod. I had it out today for about 150 rounds, and it is working almost perfectly. I note almost, in that I did get a little rubbing or scuffing on the grip tang at the top from the recoil of the gun. Pretty minor. Zero issues with the stub, below. Zero gun functioning issues, and I am very happy that I decided to try a second one. I think the cost is well worth the benefit.

You should be able to see where the red text points. This is the additional material that would need to be removed, to fully insert the stub. The hole shown (stock) would be higher, as I stopped at the point shown, so as to align the endo hole with the Gen4. If you took the material off for full insertion, it would greatly reduce the material at this joint, and would require drilling either a second frame hole, or drilling a second hole in the endo, lower. This is what I did with my first one that cracked, at the new endo hole location, which would be lower than the hole shown below.


02-11-2016, 07:33 AM
So it appears the MOD for the G4 G17 is a little too involved? I could handle some grinding and fitting but it appears pretty much a big pia.
Is it easier for me to source a G3 G17 for this stock project?
Although I love the ergos of the Gen4 as its what I'm used to and I just got another G4....

Bearbait in NM
02-11-2016, 10:05 AM
Not sure I can definitively answer. I am new to Glocks, so I do not know whether the 17 G4 has the raised area on the inside, back, inside the grip frame. If so, this is probably the hardest area to reduce. I cannot say whether it is absolutely necessary to reduce this area inside the grip frame, but if you do not, you will have to take that much more material off the stub. Removing stub material is pretty easy, as you can hold it in a vice, and "shoe-shine" sandpaper very easily.

When I broke my first one, I did not remove these ridges in the gun, and I reduced the stub for a full fit, including drilling a new hole in the stub for pin to align with the Glock grip frame hole. between the second hole, and probably the bedding material not adhering to the original hole to adequately reinforce the stub, I definitely made the stub too thin. With what I show above as my stopping point on my second attempt, I can flex the tip of the stub, and the entire endo flexes, not the stub at the hole. It seems pretty robust.

I would not classify as a PIA, but certainly time consuming, and does require at least medium skill with file and sandpaper.


Edit: Should have noted. I am pretty handy with a dremmel, but know when not to. I took a couple of passes with mine on the second fit, and knew that it was not a great idea.

02-16-2016, 04:17 PM
Glad you said something, I was thinking Dremel too but if its just patience and sandpaper Im sure I can get it done.

Bearbait in NM
02-17-2016, 09:00 AM
The sandpaper shoe shine will give you an additional benefit. As the grain of the sanding will run perpendicular on the stub, when you try to insert the stub to test, the ridges on the inside of the grip hollow will make an impression on the shoe shined surface, that run parallel. Under a good light, this impression will be places material must be removed. It's like using Dykem or sharpie on traditional metal fitting.


06-18-2016, 05:17 PM
G34 : Do as much work as you can using a small bastard file on the ridges in the grip.

Take minimal off the Endo stub.

Sent from my iPhone using Tapatalk

09-08-2016, 09:57 AM
I finally got my stock to where I like it. Gen4 17 fits pretty nice now. I sandpapered and sandpapered and sandpapered some more. I used a sharp blade a little too. Surprising how long it took to take so little material off by hand. I did not modify the Glock at all. Just sanded the brace post.

12-17-2016, 06:51 AM
I read that Endo was going to produce a Gen 4 version but haven't found a date or got any response from them as to when. Does anybody here have info?

03-26-2017, 12:24 PM
Different Firearms Instructors, have written reams of material on any kind of add on, or modifications of any nature, will get you hung, in Court.

In my HO, untrue. First sights, plastic, from the factory? Useless in reduced light. TruGlo Fiber Optics, amazing! In Sunlight, darkness, or near dark. Line up 3 green dots! So much easier to teach.

Slide release/slide lock. The Top shot in the US of A with Glock's, he used to work for Glock, Dave Syvigny. I know, I can not spell his last name! Uses this little extended slide lock, slide catch (Factory replacement) to close the slide. Me too.

Glock had nothing but bad things to say about these after market parts, till they saw how much cash they were losing! Right on the band wagon! They made them as well.

Flush fitting Butt plug. Improves magazine changes. On the Gen 4, the magazine release, bit my second finger. Sharp knife, snip, fixed.

The Sport of IDPA, is not Gun Fighting practice, but it sure teaches Pistol handling, and close up fast shooting.
And of course, that your equipment works, over thousands of rounds.

I have two Glock 19s set up identically. I carry the Gen 4 mostly, the Gen 3 sometimes as well. No real reason. So a pistol I have fired thousands of rounds through, is on my belt eating supper in our local favorite Cafe. Or at home, or on the range. No I do not carry any other pistols.

I taught for twenty five years, these pistols I feel are ideal.

08-25-2017, 09:24 PM
Okay, just had a thought. Why not use a Gen 4 grip plug. Cut the grip insert off completely and then bolt the grip plug to spot where it used to be...maybe slap a little JB weld or something between the two pieces to help shore it up. Side benifit, you can remove the plug and replace it with a gen 3 plug if you want to use the same adapter on two different pistols...
Just a thought. A lot less work and modifications to your pistol.

08-29-2017, 06:37 PM
well that sucked...turns out you have to have the tine that fits up the whole grip spacer because it pushes the top against the "beavertail" and without it...it doesn't fit right...drat.
Back to the drawing board.
Its too bad you can't get the AMG adapter that comes with the "Lock, Stock, & Barrel Kt", the connection works with a Gen 4 already AND the lock up is a bit less prone to small parts loss [its got a spring loaded pin that is part of the assembly and locks in place]. Down side, its got that weird downward cant to the stock adapter and it doesn't use a stock AR buffer tube assembly...which is probably fixable...but as I said, you can't get it without the damn 16" barrel...

Edit: Got a response from Endo...
"Hi William,

I'll be coming out with a GEN4 compatible version eventually, I just don't have an ETA for you sorry.

Modifications to the current GEN1,2,3 adapter are not something I support.


https://docs.google.com/uc?export=download&id=0B_Rv8vfy8Vq_YWdwSFRleGZzc2s&revid=0B_Rv8vfy8Vq_T25saTdkUGM3U245NXJwTEhxVHU5WWJ sL25zPQ"