The Benefits of Last Round Bolt Hold Open on your AR (LRBHO)

Posted by on July 17, 2018 . 2 Comments.

With the ever growing demand of Glock compatible pistol ARs such as9mm, 45 ACP, 10mm and 40 S&W, the question always arises on what is the difference between Last Round Bolt Hold Open LRBHO system vs. your standard AR build. So I thought, this would be a good place to start – what are the benefits of Last Round Bolt Hold Open.

LRBHO is a highly desirable feature on your blow back action rifles. Mainly it allows for a faster reload. This is when the last round is fired, the bolt will stay open, hence the term, Last Round Bolt Hold Open. Then the mag can be removed and a new one is inserted. Then a Button can be pushed to allow the bolt to close and your rifle is back in action. This is quicker than, first realizing the gun went blank, then removing the magazine and having to re-cock the action. With AR rifle with the bolt open on the last round, your eye doesn't have to leave the scope to change the mag, allowing you to stay on target and get back to shooting quicker.

Another benefit to the last round bolt hold open is that it allows air to pass through the barrel and allows it to cool down faster between magazine changes. It may not seem like a lot of time to cool down but it can sure help. This cooling only is helpful if you are firing at a fast rate.

If the bolt was not held open - you would not have a visual indication the rifle was empty. When you insert a fresh full mag into a firearm with a closed bolt there is always extra resistance as the top round is pushed down - and - sometimes can prevent proper seating or the magazine falling onto the ground. 

Thus, the main reasons for Last Round Bolt Hold Open features are

1.      It makes the reloading faster  (ideal for a tactical weapon),

2.      And it gives you a very obvious indicator when you're out off ammo.

Moriarti Armaments offers a wide variety of Glock compatible rifles and upper assemblies with a Last Round Bolt Hold Open design. Our most popular are 9mm Glock Style pistols with LRBHO and 45 ACP Complete Pistol Uppers with LRBHO.

Happy Shooting!

Tags: Last Round Bolt Hold Open, AR-45, AR-9, 9mm, LRBHO, AR-9 rifles Last update: June 09, 2019


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