What Is Behind The Difference Between A High Shelf Lower And A Low Shelf?

  • Hey Jerry, what are you doing?
  • Hi Jack, I am cleaning my rifle.
  • Ah, I forgot you are a firearm enthusiast (smile). I plan to buy an assault rifle. But when I searched for information, I met the terms high shelf and low shelf lower, and I don’t understand these words. Can you explain to me, Jerry?
  • Sure! Let me show you!
  • Ah, I wonder the difference between them as well. And I don’t know which one I should buy. Can you give me some advice as well?
  • Ok. First, I will tell you what a high shelf lower is.

Definition Of A High Shelf Lower

In weapon terms, the lower receiver (or lower frame) on a gun is a component which holds the gun’s inner parts like the action, bolt or breechblock, hammer, and other shooting mechanisms.

So why is it called the receiver? Because it is typically threaded at its front side to receive the gun’s barrel.

Manufacturers design the lower receiver with a portion of metal which is raised internal, named the shelf. It is in the receiver’s lower part where the lower component appears.

Manufacturers arrange different positions for the shelf. Some place it is at a high height, named a high shelf lower. Meanwhile, others put it is at a low position, named a low shelf lower.

Dependent on your weapon uses, the shelf’s height will lead to some effects.


A high shelf lower receiver vs. a low shelf lower receiver - img

The lower receiver is typically made of traditional materials such as stamped, machined, or forged aluminum and steel or sintered metal powders and polymers.

  • So now are you clear about the definition of a high shelf lower, Jack?
  • Yes. I got it.
  • Ok. Now let me tell you the differences between them.

Differences Between High Shelf And Low Shelf Lowers

As mentioned in their names, the high shelf lower receiver raises more elevated than the low shelf receiver. Nonetheless, this disparity is not considerable.

Just looking at the height of the high shelf and the low shelf, you can see the difference between them.

The shelf on a high lower receiver elevates about even with the bolt hole on the foot of the lower frame.

Meanwhile, the shelf on a low lower receiver elevates on foot intersecting around half way.

  • As your explanation, I need to look at the receiver so I can find out the differences between a high shelf lower frame and a low shelf lower frame.
  • Right. It is straightforward to compare them. And you know, the shelf’s height also have some effects.
  • Oh really? What are they, Jerry?
  • Let’s find out in the next part of our discussion, Jack!
  • Ok.

Effects Of Shelf’s Height

Although there is a small difference as mentioned above, a high shelf lower receiver and a low shelf lower receiver both have the same shooting way.

Ordinarily, the shelf’s height doesn't cause any impact on the way a gun performs.

Also, there isn’t any impact on a gun's trigger caused by the shelf’s height.

So what does it affect? Here is the answer to this question:

The shelf’s height will have an effect on how easily you can set up a Registered Drop in Auto Sears (shorten by RDIAS).

convert your semi-automatic rifle into an automatic one

You can convert your semi-automatic rifle into an automatic one with an RDIAS. - img

This term seems to be complicated with many shooters. Let me give you an explanation!

If you tend to convert your semi-automatic rifle into an automatic one, RDIAS is the device that makes your plan come true.

However, most weapon manufacturers almost don’t want their customers to install this device to their rifles because it is illegal or strictly regulated for automatic guns in most areas.

If shooters want to turn their weapon into an automatic rifle, high shelf lower receivers cannot stop them from it. But it is just harder to do this.

The shooters can own themselves an RDIAS which is designed to make their weapons get onto high shelf assault guns.

You can also reduce a part of the length of the Registered Drop to shorten it, allowing it to perform in your weapon.

  • This effect will a little pit affect your weapon selection.
  • In short, which shelf lower receiver should I choose, Jerry?
  • Here is my advice for you, Jack.

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Choose Your Shelf Lower Receiver

In case you want to convert your rifle into an automatic one by adding an RDIAS, a low shelf lower receiver is the best choice for you. With this wise selection, you won't have to adjust the RDIAS.

On the other hand, in case you don’t tend to adjust your weapon with an RDIAS, then which shelf lower receiver you will buy doesn't matter.

So you had better buy yourself the weapon that you like and fits your budget.

If it is finally a high shelf lower receiver and you want to convert it with an RDIAS in the future, you are still able to do it by some adjustments.

  • Ok, ok. Now I broaden my mind. Thanks so much, Jerry.
  • You're welcome, Jack.

Related Video: Everything you ever wanted to know about buying an AR15 Lower Receiver

In Brief

For you, new weapon enthusiasts, have you understand the definition of a high shelf lower and its difference with a low shelf lower?

We hope that the information we shared in this article is helpful for you.

If you have any more questions, keep visiting our site frequently!

You should read my Scope/red dot/reflex/iron sights…resource below: https://adventurefootstep.com/category/scopes-sights/

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