GST-9 MOD1 Pistol Frame

(13 customer reviews)


A high-quality pistol frame in sleek black, offering versatility and customization for firearm enthusiasts.

GST-9 mod 1 first released in November 2019, the GST-9 frame (GST-9 build kit) V1 set a precedent for the 80% frame market. It provided a modular grip system while maintaining Gen 3 G19 parts compatibility. With 3 years of customer feedback and thousands of rounds down range, we’ve raised the bar again with the new GST 9 frame!

The gas pedal shape and location were revised and re-contoured for optimized controls during the recoil cycle. The grip system of buy gst-9 frame was redesigned to guarantee a flush fit with grip modules when building out your frame. Last but not least, the rear rails were split into a 2-piece system to greatly help streamline the assembly process of GST-9 build kit.


  • Modular frame gives you the possibility of a 19, 19X, 19L, & 17-size weapon system in a single 4-in-1 platform.

  • Compatible with Glock 19 Gen 3 parts, holsters, & aftermarket accessories.

  • Ergonomic: undercut trigger guard, high beavertail, glove bevel, scalloped mag release, no finger grooves, & curved gas pedals as standard.

  • Premium internal rail components extended 3X OEM length, made of stainless steel GST-9 build kit.

  • Easily ships to your door & completes in minutes.

  • Calibers: can be built out to support 9mm (G19) /.40cal (G23) /.357 Sig (G32).

*Please Note: GST-9 MOD1 frame only accepts G19 Gen 3 compatible internal parts and slides. See all possible build combinations here. Please refer to the instructional guide for assembly tips. Visit 80% Arms FAQ for common questions and troubleshooting tips.

**The MOD1 gst 9 frame does NOT accept Glock 17 slides. The MOD1 frame only accepts Glock 19, Glock 19L, & Glock 19XL slides* 

GST-9 build kit 80 Percent Arms strives to provide the highest level of customer service within 80% and the firearm industry as a whole. We support all of our products with a lifetime warranty* so you can build with confidence.


Due to ATF regulations, we cannot legally include the jig or frame rails with the buy gst-9 frame. The jig and MOD1 frame must be purchased as two separate items. Each jig includes one set of MOD1 frame rails. You will need to purchase one jig for every MOD1 frame you plan to build. Frame rails are ONLY included with the jig, not with the 80% lower itself.


80%, 76%, unfinished frames/receivers can’t be sold with ANY other products in the same order

By using this website to purchase and/or use this product, you affirm that:

  • Permanent resident or US citizen, nor have you renounced your citizenship.

  • Never been convicted of a felony.

  • Verified that you may possess, purchase, and use this product under all applicable city, county, state, and/or federal laws

  • You have never been convicted of a crime punishable by more than one year in prison.

  • Have never been convicted of a domestic violence crime misdemeanor.

  • You have never been committed to a mental institution or adjudicated as mentally defective.

  • Not currently under a court order restraining you from stalking, threatening, or harassing a child or an intimate partner.

  • Authorize Freedom Unlimited to send emails, text messages, or other forms of electronic communications to the contact information you provide.

GST-9 build kit – NOTES:

  • All GST-9 mod 1 80% Blanks can’t be combined with any other products. (You can combine the different style of Blanks ie compact + full size and/or corresponding tool/jig kit)

  • 80% GST-9 frame blanks will not come with any instructions, It is up to the buyer to do your own due diligence. If you are not mechanically inclined, do not purchase GST-9 frame.

  • We are not Lawyers, so Please check your local and state law. When in doubt, please do not purchase.

  • Please do your GST-9 mod 1 own due diligence and research before making a purchase. It is the CUSTOMER’s responsibility to know all applicable laws that apply. Freedom Unlimited Group Inc (FU INC) is not and will not be held responsible for any city, county, state, and/or federal laws that you (the purchaser) do not comply with. Due to the volatile nature and ever-changing laws regarding unfinished frames and lowers, these items are not returnable. Warranties will be handled on an individual basis.

DISCLAIMER: GST-9 mod 1 is not manufactured, authorized, endorsed, or warranted by GLOCK, or 5D TACTICAL SELLERS. GLOCK does not warrant or represent that this product is compatible with GLOCK pistols.

Frame Color:

Black, Flat Dark Earth

Add Full Size Grip? [Add $19.99]:

Black, Flat Dark Earth, OD Green

13 reviews for GST-9 MOD1 Pistol Frame

  1. Zachary N

    Instructions are self explanatory. Setup is super easy. You don’t need a lot of tools and the finish product always comes out looking like it came from the factory.

  2. Paula Ramirez

    Amazing quality product. Feels sturdy in the hands and is crafted well.

  3. Junior

    I bought this jig with the router about a year ago and it has worked flawlessly I highly recommend this to anyone who is thinking about building their own lower from start to finish. It works very well with the 5D tactical 80% lower receiver.

  4. Franklin Lyn

    Instructions very clear. Easy to set-up. Very solid construction. Simple to use. Simply GREAT!

  5. Randy L

    Easy to setup and produces a premium product! ! beats the heck out of using a drill press!

  6. Henry

    I was really impressed with the quickness with which it came. They said usually have a wait of 3-4weeks lag-time before shipping , but received a couple weeks after ordering. Quality is also great!

  7. Thomas R

    Best jig on the planet if you want to build your own ARs from scratch. Yes there is another company selling one here in the US, it is however the exact same jig with a different logo and color. Don’t bother with them because 5D tactical has superior 80%lowers and their Custer service and support is top notch.

  8. James D

    I give it 10 out of 5 stars! If you’re concerned about whether or not you can mill an 80% lower, fear not. If you can handle a cordless drill or kitchen mixer, this isn’t any more difficult. Tape everything real well with blue painters tape. Fit the lower into the jig, set it in a vice grip and GO REALLY SLOW! That is the one thing to stress.

  9. Matt Damon

    Ok, I used this for the first time yesterday. It was perfect! This is the first 80% lower I have built and it went so well, I did two! I was amazed how sharp that bit is, lol. The quality is very good on the entire kit, after two builds and billions of shavings, the jig cleaned up perfectly and has absolutely no damage from all the work. It looks Read more about review stating First time builder, and this is the perfect solution!like new.

  10. Sir Benedict

    My review is on The jig as it is quite a marvel and engineering my problem is that it says it has a lifetime warranty but yet there are replacement parts for every piece now I’ve already wore out my side brackets and I know they should have lasted longer than I’ll let you say a few not a lot that’s not a lifetime warranty and then it’s what 64.99 Read more about review stating Very nice for the first so manyon top of replacing all the end bits and all that my phone you can remove the side sleeves and replace them but I haven’t found any of that and a quarter inch length so I just thought I’d share this review because I feel like they should last longer and I just don’t want to put 70 more dollars in something that’s whatever price for the whole thing I mean it’s a hundred bucks by the time you get done almost that’s a third of the item anyways I do recommend it I just don’t recommend the lifetime warranty on the box because that’s not true if you have to replace parts and pay for them

  11. Robert

    Everything worked perfectly, lowers came out flawless.

  12. Perez

    Does everything it should

  13. Sam A

    Went together easy, can’t wait to use it.

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