AT3™ Low Profile Micro Steel AR 15 Gas Block – 4 Sizes Available

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This premium Steel Micro Gas Block comes in 4 sizes: .625″, .75″, .875″, and .936″.

We have a fit for every barrel!


  • 4 sizes available: .625″, .75″, .825″, and .936 (.75″ is the most common size, but always measure the barrel if you aren’t sure!)
  • Low profile design, perfect with our free floating handguard
  • Steel construction (better than aluminum for withstanding extreme temperatures)
  • Secured using 2 set screws (screws, allen wrench and roll pin included)
  • Backed by the AT3 Lifetime Warranty


  • Material: 4150 Steel, Black Finish
  • Length: 1″
  • Height: Sits 3/8″ off of the barrel (fits under all free float handguards!)
  • Weight: 1.5-1.8oz depending on size
  • Packaging: PE Bag

Frequently asked questions:

Q: How can I tell what size of gas block I need?
A: The gas block size is based on the outside diameter of your barrel. The most common size is .75″ (this is the military standard). If you aren’t sure – use calipers to measure the diameter of the barrel, in the area where the gas block sits. Or alternatively, you can try looking up the make and model of your rifle online for more details.
Q: How do I know if this gas block will fit under my handguard?
A: Our micro gas blocks are as small as you will find on the market. They are guaranteed to work with our AT3 handguards, and they should be compatible with all the other handguards out there!

Products available on this page:

Have Questions About this Product?

The AT3 Tactical store has a 90 day no-hassle return policy for products in good condition. You can view the full details of our return policy here.

If you encounter an issue or defect with a product after 90 days of your purchase, you can refer to the manufacturer for a warranty claim. Their policies are below.

AT3 Lifetime Warranty Logo

All AT3 Tactical Brand Products carry a lifetime warranty against manufacturer’s defects.

This includes AT3 Red Dot SightsHandguardsIron Sights, and any other product that carries the “AT3 Tactical” or “AT3™” name. For other brands (ex. Magpul or Troy), please refer to the manufacturer’s warranty policy.

In the event that your AT3™ product becomes unusable, we will repair or replace the product at no charge to you.

If we cannot repair your product, we will replace it with a product in perfect working order of equal or better physical condition. The warranty is fully transferable, but we may require information about the original purchase to validate the authenticity of the product.

If your product is in need of warranty service, please contact AT3 Tactical to start the process

Our contact info is available here. To expedite processing, please provide your order information and description of the defect.

Please note: The AT3 Lifetime Warranty does not cover loss, theft, intentional damage or cosmetic damage that doesn’t affect the performance of the product.

Customer Reviews

Based on 109 reviews
Christopher Todecheene
.875 gas block

Great product, needed one for my build, in stock and great price thank you

Thank you for your kind words! We're glad to hear you're happy with the product.

Bigg Dawgg
Great Products from AT3

Gas block installed, free float quad rail as well and my S&W M&P 15 Sport II looks and shoots perfect. Mounting a SightMark 3-9x42 scope next. Can't wait to dial it out to 200+ yards.
Thanks AT3

Thanks for sharing your feedback, Bigg Dawgg. We're glad you're satisfied with your purchase. Cheers!

Danny Cardenas

Easy install. Fits perfect on my Ruger ar556 under an AT3 free float quad rail.

Thanks for sharing your feedback, Danny. We're glad you're satisfied with your purchase. Cheers!

Low profile gas block

Ordered a low profile gas block and quad rail.fits perfect and fast shipping

Thanks for sharing your feedback, Stephen. We're glad you're satisfied with your purchase. Cheers!


AT3™ Low Profile Micro Steel AR 15 Gas Block - 4 Sizes Available

Thank you for your review of our AT3™ Low Profile Micro Steel AR 15 Gas Block. We're glad to hear that you found our product to be available in multiple sizes. We strive to offer a range of options for our customers to choose from. Thank you for choosing AT3™!