Sunday, July 15, 2012

AR-15 Gas Block Options

DTI sponsored 3 gun competitor Michael Chambers with PRI adjustable gas block

Depending on your application, the standard or F-marked front sight base found on a "stock" AR-15 may not be the best option.  It works, and does it well. However, if you want to install a low magnification scope-low on the upper receiver or desire to increase the sight radius on a carbine or mid length, a different gas block may be the better choice.  In this post, we will discuss gas block types (we will put them in 3 categories) offered at Del-Ton and which ones would best fit the way you use your rifle.

The first type we will discuss is the low profile gas block.  These are typically a small, steel cylinder that mounts with set screws or clamp screws at the bottom of the part. DTI carries a couple of models from brands like PRI, Daniel Defense, and YHM.  There is also an adjustable model from PRI that can help ensure the proper amount of gas is channeled for cycling with supressors or different ammunition types. One of the main benefits of this style of gas block is that it allows for the use of a longer free-float handguard on the particular gas system.  If you have a carbine gas system, a mid-length or rifle-length handguard can be installed that runs well past the gas block.  This allows additional room for mounting accessories and a longer sight radius if a flip up front sight is used on the handguard.

Railed gas blocks can be beneficial in that they provide  M-1913 picatinny rail space for the addition of sights or accessories directly to the gas block. Because heat can be transferred to the gas block, only accessories made of metal should be attached.  It is important to remember to select a front sight designed for a gas block so that it will properly align with rear sights (typically, the top rail on gas blocks is a bit lower than those on railed handguards).  DTI carries single rail (one rail on the top), two rail (one on top, and one on the bottom), and four rail gas blocks in this style.  Again, the main advantage here would be no fixed front sight to disturb the sight picture of optics with low magnification or a low mounting profile.

The final type of gas block we will discuss is those that come with a flip up sight on the part.  This can be a definite money saving opportunity.  DTI carries models from YHM, PRI, Vltor, and A.R.M.S. that allow you to use the iron sight when it is in the up position or folded down so that a clear, unobstructed view can be obtained.  They may cost a bit more than the models with rails, but with the sight included they end up being more cost effective. 

Installation of these is simply a matter of removing the muzzle device and the front sight base.  DTI front sight bases are installed with taper pins and these should be driven out from the bolt assist aside of the weapon. A larger punch should be used first to get the pins "moving" and then a smaller punch can be used to finish tapping them out.  A front sight base bench tool, like those sold at Brownells, is extremely handy for this task. Be sure to remove the gas tube roll pin and gas tube gently so that they can be reused if needed in the gas block (however, this is an excellent time to install new parts if you are concerned about their condition). It is typically easier to install these in the gas block before mounting the gas block on the barrel. It is also important to note that a low profile gas block may not cover the mark in the barrel where the front taper pin was installed.  Most of the railed and flip up front sight gas block models will cover both of the marks left by the taper pins for a more aesthetically pleasing appearance. Finally it is imperative to make sure the gas block is properly aligned over the gas port and in line with the upper receiver to ensure proper functioning. 

Thanks for reading our blog. If you have any questions about the gas blocks we carry or any other AR related questions, please feel free to contact us.


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