GST-9. Pros and Cons

[seniormoment]

I remember, from the old forum, that there were some issues with this product. Other than the problems with filling orders what was wrong? Was it a safety issue and was it corrected with their MOD1 version. Doesn’t seem to be that many people building them, or at least I haven’t heard much.

 

[GSW10]

So... Yeah. In the earlier versions of Glock pistols, Gen 2, they discovered higher-powered calibers, even 40 S&W, were capable of causing frame failure. So, they started introducing a 'Third Pin", high into the rear of the Locking Block above the Trigger Pin to support the Block during recoil and spread-out the forces acting against the frame... Polymer 80 included this updated design, which Glock retained all the way through the end of Gen 4.

The GST-9 however... Two-Pin design. When asked about higher-power calibers, i.e. 40 S&W and 357 Sig, 80% Arms initially said (and I am paraphrasing of course), 'heck yeah, our awesome frame is so awesome it can awesomely handle anything!' Then later, they seemed uncertain about 'mere' 9mm +P, and walked-back their previous statement of awesomeness, saying that the GST-9 'stands for 9mm, and ONLY 9mm'... Possibly just some miscommunications with their CS and technical staff? And to note, Glock's Gen 5 is back to "Two Pin" designs, either because their new polymer is strong enough to take the stress, or they just decided saving $1 on the third pin will be more economical than replacing a few cracked frames over the years?

Much more of a concern is the GST-9's rear rails, which are notably thinner than P80 rails, and it was discovered that in some cases, the slide has enough 'rocking' free-play that stable Sear-engagement becomes a concern. I don't remember hearing of any actual malfunctions due to this however, and not all slides seem to be loose enough to cause slide-rattle -or perhaps it is an inconsistency in Rail manufacturing? The way I test for Sear engagement would pretty well prove functional safety or not though, and I don't do too much all that special, just a few dynamic tests that aren't in the book.

Some Builders reported the Nickle-Boron coating wasn't that durable on the Rails or the FRLB component. I never saw any chipping or flaking personally however, and if it all chips off, then what? No one else had the coating anyway, so unless that made the rails much thinner...

No experience with the MOD-1, no idea what (if anything) they have done about the rails. I don't see much negative comment about them though.

The issues are, as you alluded to, more an issue with the company itself, that they lied to customers for several months about production and held on to "pre-order" sales money for many months longer than promised. They stole tag-lines regarding 'First Time Quality' from MGB after refusing his technical assistance or feedback, and allegedly subverted him on social-media as well. So, the denouncement of the GST-9 is overall a 'political' one. I personally have nothing against any Builder who wants to have the GST-9, and fairly little against the product itself thusfar, but have a lot of negative feelings about the company that makes them. But that is just my personal take.

 

[seniormoment]

So... Yeah. In the earlier versions of Glock pistols, Gen 2, they discovered higher-powered calibers, even 40 S&W, were capable of causing frame failure. So, they started introducing a 'Third Pin", high into the rear of the Locking Block above the Trigger Pin to support the Block during recoil and spread-out the forces acting against the frame... Polymer 80 included this updated design, which Glock retained all the way through the end of Gen 4.

The GST-9 however... Two-Pin design. When asked about higher-power calibers, i.e. 40 S&W and 357 Sig, 80% Arms initially said (and I am paraphrasing of course), 'heck yeah, our awesome frame is so awesome it can awesomely handle anything!' Then later, they seemed uncertain about 'mere' 9mm +P, and walked-back their previous statement of awesomeness, saying that the GST-9 'stands for 9mm, and ONLY 9mm'... Possibly just some miscommunications with their CS and technical staff? And to note, Glock's Gen 5 is back to "Two Pin" designs, either because their new polymer is strong enough to take the stress, or they just decided saving $1 on the third pin will be more economical than replacing a few cracked frames over the years?

Much more of a concern is the GST-9's rear rails, which are notably thinner than P80 rails, and it was discovered that in some cases, the slide has enough 'rocking' free-play that stable Sear-engagement becomes a concern. I don't remember hearing of any actual malfunctions due to this however, and not all slides seem to be loose enough to cause slide-rattle -or perhaps it is an inconsistency in Rail manufacturing? The way I test for Sear engagement would pretty well prove functional safety or not though, and I don't do too much all that special, just a few dynamic tests that aren't in the book.

Some Builders reported the Nickle-Boron coating wasn't that durable on the Rails or the FRLB component. I never saw any chipping or flaking personally however, and if it all chips off, then what? No one else had the coating anyway, so unless that made the rails much thinner...

No experience with the MOD-1, no idea what (if anything) they have done about the rails. I don't see much negative comment about them though.

The issues are, as you alluded to, more an issue with the company itself, that they lied to customers for several months about production and held on to "pre-order" sales money for many months longer than promised. They stole tag-lines regarding 'First Time Quality' from MGB after refusing his technical assistance or feedback, and allegedly subverted him on social-media as well. So, the denouncement of the GST-9 is overall a 'political' one. I personally have nothing against any Builder who wants to have the GST-9, and fairly little against the product itself thusfar, but have a lot of negative feelings about the company that makes them. But that is just my personal take.

Thanks for the information, much appreciated.

 

[James Moore]

I've built several GST-9s and had to modify the rear rails on a couple just like the Polymer80s, but The newer Mod-1 comes with the 2 piece rear rails and work great.

 

[seniormoment]

I've built several GST-9s and had to modify the rear rails on a couple just like the Polymer80s, but The newer Mod-1 comes with the 2 piece rear rails and work great.

I have both, got them as blems and I couldn’t find the flaw they mentioned in their ads. Just wondering what safety issues I might face once completed.

 

[GSW10]

I have both, got them as blems and I couldn’t find the flaw they mentioned in their ads. Just wondering what safety issues I might face once completed.

Complete the standard procedures of safety checks, if it passes all should be fine. For Sear engagement, here is my procedure:
-With Inspection Backplate installed for maximum visibility and access, rack the slide back and verify the minimum 2/3rds are attained -Yeah, I am not comfortable with less than 80% though...
-Holding the front of the gun, squeeze the slide/barrel assembly together and verify the rear of the slide hasn't 'lifted' the Striker Lug off the Sear. This may be a fair simulation of the firearm riding in a tight holster. (On a GST-9, this may be the most critical change in the normal procedure, if the rear rails are too thin and allow the slide to raise and lower too much, but this is how I test ANY frame-type or Sear engagement). Verify the Striker Lug stays correctly engaged while grasping the rear of the slide and pulling 'up' while twisting side-to-side (with REASONABLE force -don't get out a crow-bar! ). Place a slight pressure on the trigger and check again to see if the Sear engagement remains the same -I like to pull it all the way back to 'the wall', this is where you will see failure if it will fail. Slap the slide from every angle you can while the trigger is pulled back to 'the wall'. Using a small punch, push down on the Cruciform -the 'Ledge' in the Trigger Housing should prevent it from separating from the Striker Lug. (This is where the Armorer's Inspection Plate is REQUIRED -you CAN see through past a 'regular' Back Plate, but cannot really access to Cruciform physically. Now, load in a mag with dummy-rounds, repeat the whole process now with that pressure pushing on the slide.

These are the last steps (for me) before drop-testing.

 

[seniormoment]

Complete the standard procedures of safety checks, if it passes all should be fine. For Sear engagement, here is my procedure:
-With Inspection Backplate installed for maximum visibility and access, rack the slide back and verify the minimum 2/3rds are attained -Yeah, I am not comfortable with less than 80% though...
-Holding the front of the gun, squeeze the slide/barrel assembly together and verify the rear of the slide hasn't 'lifted' the Striker Lug off the Sear. This may be a fair simulation of the firearm riding in a tight holster. (On a GST-9, this may be the most critical change in the normal procedure, if the rear rails are too thin and allow the slide to raise and lower too much, but this is how I test ANY frame-type or Sear engagement). Verify the Striker Lug stays correctly engaged while grasping the rear of the slide and pulling 'up' while twisting side-to-side (with REASONABLE force -don't get out a crow-bar! ). Place a slight pressure on the trigger and check again to see if the Sear engagement remains the same -I like to pull it all the way back to 'the wall', this is where you will see failure if it will fail. Slap the slide from every angle you can while the trigger is pulled back to 'the wall'. Using a small punch, push down on the Cruciform -the 'Ledge' in the Trigger Housing should prevent it from separating from the Striker Lug. (This is where the Armorer's Inspection Plate is REQUIRED -you CAN see through past a 'regular' Back Plate, but cannot really access to Cruciform physically. Now, load in a mag with dummy-rounds, repeat the whole process now with that pressure pushing on the slide.

These are the last steps (for me) before drop-testing.

Thanks again

 

[James Moore]

Just wondering what safety issues I might face once completed.

I sure that you would have no more safety issues than with any other completed firearm.

 

[seniormoment]

I sure that you would have no more safety issues than with any other completed firearm.

Good to know. Thank you

 

[SNBI125]

I just finished my first GST-9 (Mod 1) build yesterday. Still waiting on a trigger to arrive before I can get it to the range, so I can only attest to the build process. I've done six P80 builds of various models, so it helped to have some experience, but I think my comments would be the same even if I had only done 1 or 2.
Overall I think the jig and drilling/milling process are far superior with the GST-9. It uses 6 screws to clamp the two sides together, so there's a tight and secure fit with no need to tape. A drill press is recommended which intuitively would seem to produce better results than free-hand work, but I know that is strongly discouraged for the P80s. The guide holes for the drill bits are extended and it was very easy to get perfect holes and the pins installed perfectly.
The rail tabs are virtually identical to the P80s, but the channel tab was MUCH easier to deal with. It's at the very front of the frame, rather than set back inside the channel, and there is an opening in the jig to use as a guide. You still have to be careful not to mill right into the jig, but it's still better than doing the Dremel work entirely free-hand.
The front locking block seemed very solid, and the rear rails which are two pieces were easy to install and pin with no problem. There is still no 3rd pin with the Mod-1, as someone asked about.
Other pluses are the interchangeable grip modules, letting you easily switch between a G19 and G19x configuration, and compatibility with Glock holsters (and, it seems, my P80 holster).
Looking forward to getting this to the range, we'll see if my good impressions hold up. But just based on the build process, I would easily choose the GST-9 for any future build that the platform is capable of. It does say you can do a G19L or G17 configuration, even though it says you can't use a G17 slide so I'm a little confused about that, and G19L slides seem to be pretty rare.

 

[GSW10]

It does say you can do a G19L or G17 configuration, even though it says you can't use a G17 slide so I'm a little confused about that, and G19L slides seem to be pretty rare.

Nice review, well written, thank you.
To help clear it up regarding the G17 slide, yes you CAN use a G17 slide, BUT you MUST use a slide-adapter like this:

Otherwise the slide WILL over-extend during recoil.

Since the GST-9 is designed to use Gen 3 parts, particularly the RSA, the G17 slide will present another problem... The G17 barrels for Gens 1-4 use a different locking-lug than the G19, and they cannot be used on the GST-9. Okay, so just use a Gen 5 G17 barrel (aka "G19L" -same thing, trust me), right? Mmmmm, the problem there is the different Locking Lugs on the G17 Gen 5 barrel, while working fine in the GST-9 frame, won't hold the Gen 3 RSA in place -the RSA is too short to reach the Gen 5 barrel Lugs, and the Gen 5 RSA won't fit in the GST-9 frame... Aaaagh!
Solution: LWD offers a special 'uncaptured' Guide Rod that is the right length to fit this mish-mash configuration. I am spoiled for Glock's "captured" Recoil Spring, so my solution is to use a G20 Stainless Steel RSA and shim the end -the G20 RSA is almost the perfect length... Another solution is to use something like Strike Industries' Jitter Plug in the end of an OEM G20 RSA to shim it forward a smidge.

Overall, you get the same effects of a G17 slide without the extra parts and hoops to jump through if you use a G19L slide, designed for the Compact-size frame, so that is what I typically recommend doing. Ahem, though I do have a 'number' of these bastardized longer slides mounted to Compact frames, but took it a step further, G34, G35, and even G24 (the 40-cal models swapped to 357 Sig chamberings). For me, I prefer the longer barrel and superior sight-radius of the longer slides, but prefer the shorter grip of the Compact frame -my only options are to cut the grip down, or use the discontinued PF940CL frames.

 

[SNBI125]

Thanks for all the info, good to know! I may wait and see whether they come out with any other frame models before going with the mish-mash approach. I am not sure whether they even have any in development or not - I'm sure they're busy enough just trying to stay in business these days. But they do offer several variants for their AR platform lowers (AR-15, 9mm, .308) so I'd sort of expect them to eventually come out with a few different frame size options for their 80% Glock line. Right now I have two P80 G19s plus this GST-9, so I'd really rather build another G17 or G34 before another model with a G19 slide.

But let me see if I understand correctly what the configuration you're talking about would be...
G17 slide w/ slide adapter
G17 Gen 5 barrel
LWD "uncaptured" Guide Rod OR
G20 RSA w/ shim or Jitter Plug

Also, which LWD guide rod is the "uncaptured" one? I see a bunch that don't say "captured" but none that specifically say "uncaptured."

 

[GSW10]

But let me see if I understand correctly what the configuration you're talking about would be...
G17 slide w/ slide adapter
G17 Gen 5 barrel
LWD "uncaptured" Guide Rod OR
G20 RSA w/ shim or Jitter Plug

Also, which LWD guide rod is the "uncaptured" one? I see a bunch that don't say "captured" but none that specifically say "uncaptured."

Yep, that is the recipe. I find LWD parts for this to be overpriced. Their 'new' site doesn't give specs on the Guide Rod, but this SHOULD be it:

LWD S/S Guide Rod for use with Slide Adapters

Lone Wolf Arms is the largest manufacturer of aftermarket parts for Glocks. We also have M&P Shield, Beretta/Taurus, and Browning Hi-Power parts.

lonewolfdist.com

I would recommend contacting them if you intend on going this route, and verify the application. If they give you a specific overall length and you aren't 100% sure, let me know and I will take a measurement for you.

@Hawkeye used one of their slide adapters I believe, and had some trouble fitting it. You may also want to read up on his thread in the "Freedom Wolf" section, or contact him directly for some input -he is an advanced Builder with a ton of knowledge. He used a larger RSA from a Gen 4 or Gen 5, since the Freedom Wolf frame is actually based on Gen 4 primarily, and has that option.

I have not used the LWD adapters personally. I fabricate my own, I have used milled acrylic, formed steel, and milled an industrial polymer -I trust the polymer the most but the acrylic looked the best. I didn't like the formed steel option, and will (man, I have been saying this for years now) eventually replace them all with milled brass. You can also 3D-Print these adapters, that seems to work well.

 

[SNBI125]

Ok, thanks a lot for the info. I have three other builds queued up so I'll see what my options are when I get back to another Glock platform build.

 

[Hawkeye]

I thought I had posted this, but I couldn't find it so to help out with questions I will do a wright-up. Now that I have gone through all the steps, I did to make this work fine so far.

My Young Wolf build uses a gen4 G-17 slide with gen5 G-17 barrel and RSA.
To make it work on a Freedom Wolf frame I used a LW adapter dust cover, but I had to do some hand fitting to get the dust cover to fit.

The radius at the end of the rails were bigger than the dust cover so that had to be increased plus I had to cut a step into the dust cover for a clean fit.

After all the hand fitting for a clean fit with the dust cove it looks and fits my gen4 slide.

Now on to getting the gen5 RSA to work.

What I did to keep the RSA from dragging on the dust cover was to remove some stock and polish in just the (A) area.
In the (B) area you don't need to remove any stock because this step is where the end of the RSA sits.

You may need to do a little polishing if you notice any drag. I had to polish somemore after range testing to clean up drag. What I ran into was every third round would stove pipe. After polishing the drag marks and a good oiling this cleared up.

Here is the RSA I used its a gen5 from LW.
The way it fits, you have about 1/4 inch that has to be compressed to fit into the barrel lock, but it seems to be working fine. I tried a bunch of RSA to see if any fit better (gen 3-4-5) this was the only one that came close all the others where short.

Hope this helps but this is for a LW, I haven't worked on a GST-9 yet maybe down the road. This should work for the GST-9 because you're only taking about the slide and getting it to fit a G-19 compact frame.
The reason for the gen5 barrel and RSA is the way the gen5 G-17 barrel-lock matches up with a Gen3 G-19 barrel, they are the same.

Any time you do mods like this you need to do a lot of homework and get this type of build Stright in your plan before starting.
Having a good plan to start helps out with the whole build turning out to be a great range pistol.

 

[GSW10]

The way it fits, you have about 1/4 inch that has to be compressed to fit into the barrel lock, but it seems to be working fine. I tried a bunch of RSA to see if any fit better (gen 3-4-5) this was the only one that came close all the others where short.

Hope this helps but this is for a LW, I haven't worked on a GST-9 yet maybe down the road. This should work for the GST-9 because you're only taking about the slide and getting it to fit a G-19 compact frame.
The reason for the gen5 barrel and RSA is the way the gen5 G-17 barrel-lock matches up with a Gen3 G-19 barrel, they are the same.

Any time you do mods like this you need to do a lot of homework and get this type of build Stright in your plan before starting.
Having a good plan to start helps out with the whole build turning out to be a great range pistol.

Right, this exactly regarding doing your homework. Setting up a G17 (or G22 or G31, even G34, G35, G17L or G24) slide onto a Compact frame is going off-road, but others have blazed this trail so you don't have to leave the maps behind. Just to note clearly, the Freedom Wolf @Hawkeye did this conversion to uses Gen 4/5 parts, and the RSA he used will NOT work in a GST-9 frame, and the adapter he used is LWD's Gen 4 specific piece, their Gen 3 slide adapter is a little different (though I wouldn't be surprised to see the same fitment issues).

@Hawkeye, I am surprised you don't have issues with your RSA being pre-compressed (like stove-piping or failure to feed) -the spring SHOULD seat at the front of the slide, not 1/4 inch back in the dust-cover, if I am seeing this right in your pics... I would think the Gen 4 G17 RSA would seat-in about right. But what works works... Thanks for posting this up.

 

[Hawkeye]

Right, this exactly regarding doing your homework. Setting up a G17 (or G22 or G31, even G34, G35, G17L or G24) slide onto a Compact frame is going off-road, but others have blazed this trail so you don't have to leave the maps behind. Just to note clearly, the Freedom Wolf @Hawkeye did this conversion to uses Gen 4/5 parts, and the RSA he used will NOT work in a GST-9 frame, and the adapter he used is LWD's Gen 4 specific piece, their Gen 3 slide adapter is a little different (though I wouldn't be surprised to see the same fitment issues).

@Hawkeye, I am surprised you don't have issues with your RSA being pre-compressed (like stove-piping or failure to feed) -the spring SHOULD seat at the front of the slide, not 1/4 inch back in the dust-cover, if I am seeing this right in your pics... I would think the Gen 4 G17 RSA would seat-in about right. But what works works... Thanks for posting this up.

I tried a gen4 RSA, but it was short because I think the barrel lock is like a gen3. Hey, I really jumped out of the box with this one.
GSW10 your right at first, I had stove pipes after three shoots, then polishing help this, from what could see it was RSA dragging. I haven't had it out since I finished the build but will be soon for a final check-out. I looked at this as an RSA problem, but it may be an adapter being the wrong one for what I am trying to do.
I don't like how the RSA is sitting in the dust cover adapter, it only sits on half of the end of the RSA. This looks to me like a failure waiting to happen. If this problem shows up again (stove pipe) I will look into a different adapter but then the problem will be getting an RSA that is long enough. Like I said this is my first time down this road and have a 19 slide on a SC coming up and hope I don't run into the same problems.

 

[GSW10]

Th

I tried a gen4 RSA, but it was short because I think the barrel lock is like a gen3. Hey, I really jumped out of the box with this one.
GSW10 your right at first, I had stove pipes after three shoots, then polishing help this, from what could see it was RSA dragging. I haven't had it out since I finished the build but will be soon for a final check-out. I looked at this as an RSA problem, but it may be an adapter being the wrong one for what I am trying to do.
I don't like how the RSA is sitting in the dust cover adapter, it only sits on half of the end of the RSA. This looks to me like a failure waiting to happen. If this problem shows up again (stove pipe) I will look into a different adapter but then the problem will be getting an RSA that is long enough. Like I said this is my first time down this road and have a 19 slide on a SC coming up and hope I don't run into the same problems.

Yep, the Gen 4 G17 barrel lugs are spaced the same as the Gen 3, absolutely correct. The Gen 5 G17 RSA, P/N 33786, should be the correct one for your configuration, but using the Gen 5 barrel the RSA should settle into the hoop in the front of the slide, NOT into some arbitrary notch in a dust-cover -this is pre-compressing the spring, and may even cause failure or excessive wear at some point.
You can verify the fit by just dropping the barrel and RSA into the slide without the LWD adapter, then notch the slide in place on the frame (fine so long as it isn't fired this way, or racked-back too far by hand), and use dummy cartridges to verify feed and ejection. I will say pretty certainly that if the RSA is too short to notch into the Gen 5 barrel lugs and reach the RSA 'hoop' in the front of the slide, that the RSA you have isn't a Gen 5 G17. Probably a Gen 4. For Gen 5, it should be marked "1-3".

 

[Hawkeye]

Th

Yep, the Gen 4 G17 barrel lugs are spaced the same as the Gen 3, absolutely correct. The Gen 5 G17 RSA, P/N 33786, should be the correct one for your configuration, but using the Gen 5 barrel the RSA should settle into the hoop in the front of the slide, NOT into some arbitrary notch in a dust-cover -this is pre-compressing the spring, and may even cause failure or excessive wear at some point.
You can verify the fit by just dropping the barrel and RSA into the slide without the LWD adapter, then notch the slide in place on the frame (fine so long as it isn't fired this way, or racked-back too far by hand), and use dummy cartridges to verify feed and ejection. I will say pretty certainly that if the RSA is too short to notch into the Gen 5 barrel lugs and reach the RSA 'hoop' in the front of the slide, that the RSA you have isn't a Gen 5 G17. Probably a Gen 4. For Gen 5, it should be marked "1-3".

You must get tired of hearing it, but you are absolutely right!!!!
Without dust cover fits fine.

So, as it looks like I have the wrong adapter.

Already spending bucks on the wrong adapter, I just removed the step in the adapter so the RSA could run without interference with the adapter.

All good now, tomorrow if it is not raining, I will do a test in the backyard range for final testing before I call this one a finished build.

GSW10 Thank you very much, this has been bugging me though out this build. Now I can start planning a G-19 slide on a SC frame after LW build two is finished (next build). I try to do my homework on builds long before I start them, Thanks again

 

[GSW10]

GSW10 Thank you very much, this has been bugging me though out this build. Now I can start planning a G-19 slide on a SC frame after LW build two is finished (next build). I try to do my homework on builds long before I start them, Thanks again

You are absolutely welcome. I thought this had ironed-out already for you, but so glad to hear it is in the right direction now -nice work grinding out that dust-cover...

Um, but now we need to talk about that G19 slide on the Sub-Compact frame.... Please don't. I think all the posts are long-gone now, but Bapegg and I had tag-teamed this a few times. The angled cut-out in the Sub-Compact (G26) slide for the Slide Stop is a unique cut, steeper angled and a shorter cut. This is because the cut-out from any other model slide will actually expose virtually ALL of the front left rail... Leaving the front left of the slide unsupported in full battery, at the moment recoil begins. Very unsafe. Bapegg also had a video where he grabbed his G19 slide on a G26 frame, pushed it to the right with a little wiggle and the slide literally fell off. Even IF there is a sliver of front-rail still unexposed by the G19 slide's Slide Stop notch cut-out, it will only be a sliver -not a very good margin of safety or durability...

While not as 'innovative', this is far safer and more reliable:

New Release!!! Remsport G26L Slide with Front and Rear Serrations

TR Enabling is a division of Remsport Mfg. Remsport Mfg manufactures AR-15 and 1911 parts. Remsport manufactures premium 1911 components and parts. Remsport specializes in the production of barrels for 1911, Glock, M&P, Browning, Smith & Wesson and other platforms.

www.tr-enabling.com

When they released this slide, I was practically drooling over it -but I just didn't have any Sub-Compacts lined-up for Building. Almost hurt not to buy this (RemSport has really impressed me with their finish quality, pricing, and delivery. Just my experience, I would use them again without hesitation). Uses a straight G19 (any Gen) barrel and a Gen 3 G19 RSA. There are a couple other brands out there who make this slide configuration, but they are much more expensive, and I don't think they are any better quality.