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MMS - ALL 1913 Gas Tubes (Color Options)
GTMSRP $124.95 - $129.95The JMAC Customs™ MMS Handguard Gas Tube is designed to enhance the functionality of your MMS handguard system. It provides additional 1913 rail space for mounting optics and other accessories, while...
Description
The GBC-13 is a high-quality replica of the East German 74nk gas block, designed to enhance AK builds with a lightweight yet durable construction. Precision-cast from 4140 steel, machined, heat-treated, and black nitrided in the USA, it offers exceptional strength and corrosion resistance. The detent version is ideal for SBRs and pistols, while the non-detent option suited for rifles with pinned and welded muzzle devices. Choose between the standard version or the adjustable model, which allows for fine-tuned gas flow.
Key Features:
- Authentic Design – Classic East German 74nk style
- Versatile Fit – Works with 0.591" barrel journals, fits 90° gas ports (45° with minor mods)
- Durable & Corrosion-Resistant – Heat-treated 4140 steel, black nitride finish
Specifications:
- Constructed from durable 4140 Steel casting and precision machined
- Black QPQ Nitride Finish
| GBC-13 Gas Block Combo | Compatibility | Weight |
| Without Detent Hole (GBC-13-WO) | AK-74 Pin and Weld | 3.56 OZ |
| With Detent Hole (GBC-13-W) | AK-74 SBR/Pistols | 3.52 OZ |
| Without Detent Hole Adjustable (GBC-13-WO-ADJ) | AK-74 Pin and Weld | 3.56 OZ |
| GBC-13 Non Adjustable (GBC-13-W-ADJ) | AK-74 SBR/Pistols | 3.52 OZ |
⚠ Important Notes:
We recommend having a Kalashnismith install this product.
Reviews (18)
18 reviews
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5 Great Option!
Craig Shaw on Apr 17th 2025
Grabbed one of these to have my AK barrel cut, pinned, and welded. Adjustable gas to cut down the typical AK overgassness (it’s a thing and a real word lol) Gets weight off the end of the barrel. Better balance and shooting.
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5 GBC-13 Gas Block - Without Detent Hole
James on Jul 15th 2024
Fit my PSA AK103 perfectly. Pin holes were marked for drilling. I’m very happy with the look and new balance of my rifle.
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5 FSB/GB
KEVIN Shannon on May 12th 2024
Excellent quality, haven’t used this one yet but have used them before. I wish someone made a copy of the Draco FSB of this quality.
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4 Detent
John on Feb 8th 2024
The detent itself fit my stamped Romanian ak perfect. However the spring included in this pack was atleast 1/8" longer than the original so it didn't allow the detent to seat low enough to work (keep your original spring) also doesn't come with the keeper pin so don't loose that. Price and shipping was good and fast
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5 GB-13
Josh Randall on Sep 14th 2022
I have found JMAC products to be in spec, and have an acceptable finish. They have functioned flawlessly in my experience. I plan to continue to use their products. Thank you.
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5 Adjustable gas block
David on Mar 14th 2022
We build custom AK-47 rifles. The JMac parts are always the ones we reach for first. You can't go wrong with these. Great fit, great function, and it looks cool.
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5 gas block
clay on Mar 11th 2022
even more fantastic in person than in pics and vids. I am looking forward to my next purchases for my next projects.
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5 gas block
clay on Mar 11th 2022
even more fantastic in person than in pics and vids. I am looking forward to my next purchases for my next projects.
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5 gb13 and cs
tony Smith on Feb 22nd 2022
I run hard shoot fast. 3gun is tough and takes its toll. adj gas block is a great add on and if your like me and damage one, JMAC will back you up.. It may have been a flaw in the part. It may have been me punchin through barricades. regardless. I have a replacement in time. Im good to go without missing a match. Ash is hot
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5 GB-13
Josh Randal on Dec 29th 2021
These folks make high quality and well finished items, I have been pleased and impressed with their outstanding customer service. I will be a continuing customer.
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5 Gbc-13
Dale Henderson on Aug 2nd 2021
Awesome piece! Really added some character to my build. Amazing quality! Do not hesitate to buy.
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5 GBC-13
Ronnie Jones on Apr 20th 2021
These combo blocks are always great. Quality is consistent and great.
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5 gasblock sight combo
Raymond Zeigler on Apr 2nd 2021
PERFECT! Good price, FAST shipping and very well made product. I will be purchasing another. I was pleasantly surprised by how much the balance of my rifle improved following the install of this gas block sight combo. 5 star review!!!
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5 Quick shipping, great communication and answered all of my questions about the products that I am interested in. Almost of all, amazing products!!!
Chase Dela Cruz on Aug 27th 2020
Bought 2 non detent gas block sights and they came well packaged. The product itself is real good quality and the coating is beautiful!!! Worth every penny!!! Great product and people to do business with.
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5 Gbc-13
Jeremiah Johnson on Feb 5th 2020
Superb quality casting and machining as well as the finish and fits the jmac barrels perfect.
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5 Quality
Issac Karnes on Apr 3rd 2019
Super clean , nice finish and well built . One drawback is you need a press to install . That is expected though. This will take weight off of your ak. But one!!
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5 Excellent product
Michael Griffith on Mar 15th 2019
Bought this gas block for a custom 5.56 build I am doing. Not only does is look great, it is a very high quality part! Love it, 10/10 would buy again!
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5 Excellent product
Michael Griffith on Mar 4th 2019
just received my GBC-13 and will be using it on a 5.56 pistol build. This is a beautifully made product!