Part Two: Battle Arms 45* Short Throw (ST) Ambidextrous Selector

By: Bryan Reed

In this second part of the three part series we are looking at the Battle Arms Development 45* Short Throw Selector (ST) selector system. Last month we covered the BAD A.S.S. system which allows ambidextrous manipulation of the fire controls on any AR-15 or AR-10 series rifle. The unique design of the BA selector systems allows you to customize which levers you use on your carbine to best suit you as an individual shooter.

This time we installed the BAD 45* ST on my LMT carbine and right out of the package you will find the precise machining and quality that you would expect from a manufacturer like Battle Arms. Just like their other selector systems, the 45 ST is made from 12L14 solid bar stock steel and comes with a new KNS Precision detent, two levers in your choice of length, and a Torx wrench. However, the 45* ST has one particular feature you will not find on the rest of their selector groups- a stainless steel pin approximately 2mm x 2mm that protrudes from the assembly itself.

What does a 45* Short Throw selector do?
The advantage of a 45* ST selector installed on a lower receiver is that the selector lever only has to move half of what it normally would in order to go from Safe to Fire. This results in a faster, smoother manipulation of the fire controls and less wasted movement. Take your own rifle and see how your thumb actually can have to move in two separate directions in order to place the rifle on Fire (down then forward). On the 45* ST it only takes a smaller push downward to get the level to go to fire. Coupled with their short levers that are grooved for grip it makes it very fast, smooth and positive when going from Safe to Fire. Ultimately this means that as the shooter you have the ability to be faster on the trigger and when you are in a gun fight for your life, there is no prize for second place.


What is the purpose of the steel pin?
The steel pin serves a unique purpose- it prevents you from installing it on a standard lower receiver. A typical lower receiver is marked with the Safe position at the 9 o’clock and the Fire position at the 12 o’clock. The Safe position remains in the same location but since the 45* ST selectors’ Fire position is a short throw it falls between the 10 and 11 o’clock position, it would not actually point to Fire, thus someone could be led to believe that the rifle is malfunctioning or on Safe and ultimately have a negligent discharge. Now, knowing that Rule #1 applies (Keep your finger off the F*$&ing Trigger!), not all people will get or understand it aside from the owner. So by adding the steel pin, it makes the 45* ST selector non-compatible with a standard receiver without modification. Here is the good news: Rainier Arms will soon be releasing a lower receiver that has the properly placed fire control markings and the relief hole for the steel pin on the 45* ST as well as some other very unique features. For more information about the lower receiver you can contact Battle Arms Development or Rainier Arms for more information.



Installing the 45* ST:
The installation of the 45* ST is almost exactly the same as installing a BAD A.S.S. selector kit. The only difference is you will have to figure out how you want to work around the steel pin. Remember, prior to installing this selector or performing any other work on your rifle; ensure that the rifle is unloaded and safe. If you do not have the tools or skills required to perform the job properly I highly suggest taking the rifle to a qualified and reputable gunsmith to conduct the installation.

Step #1- Start by removing the upper receiver and placing it off to the side. Then remove the bolt that holds the pistol grip by going through the bottom of the grip itself. This typically requires a flat head screwdriver or hex wrench.

Step#2- After you have removed the pistol grip bolt, slowly remove the grip. Be careful not to lose the detent spring as this will be needed to reassemble the selector. Once complete, the old detent pin can be discarded or retained as a spare (I recommend you keep it as a spare as you never know when you may need it).

Step#3- Remove the stock selector lever and either discard or retain as a spare. Note: The lower must be in the hammer back (ready to fire) position in order to remove the selector lever.


Step#4- Here is where you will have to make a choice as you can see the 45 ST will not go into the lower due to the steel pin. You have to now make a decision on which method you want to use to allow the 45 ST to fit.

Option #1: Using a small file or metal jigsaw blade, cut a relief hole in your lower receiver at the 12 o’clock position. Remember to go slow and only make the relief cut big enough for the pin to slide through. Check it after every few swipes with the blade or file to see if the pin will pass though the hole.

Option#2: Using a file or Dremel Tool, grind down the steel pin flush with the rest of the selector assembly body. Again, go slow and check for fit often only taking away as much material as needed.

Though I am not against modifying my lower receiver if I have to, I chose to remove the steel pin by using a Dremel tool fitted with a cone shaped grinding stone. However take note; according to Battle Arm’s web site, any modification of the assembly (like grinding away the pin) will null and void the warranty of the 45* ST. With the Dremel it took less than 1 minute to completely grind away the pin and allow for unimpeded installation of the selector body into the lower receiver. Here is the process that I chose to use.

Remove both selector levers from the assembly and secure the assembly in a bench vice or using vice grips or clamps to keep it from moving while performing the modification. I also used an old t-shirt to help protect the assembly from being marked by the vice. Remember don’t tighten the vice down so much that it distorts the assembly. Just tighten it enough to secure the assembly during the grinding process.



Step#5- Once you have completed removing the pin or cutting a relief hole, install one lever on the left side of the assembly (opposite side of where the detent holes are made) and insert the 45* ST assembly from left to right. Turn rifle over and install the selector lever on the right side and swivel the lever assembly to make sure it moves freely with no binding and then place in the selector in the Safe position.

Step#6- Insert the KNS detent pin into the hole on the underside of the receiver, install the detent spring and reinstall the pistol grip.

Once you have completed this you are done with the installation. Reinstall the upper receiver and perform a functions check to make sure the rifle will operate correctly. If you have other sized levers in your kit you can experiment with using different sizes and lengths to customize your selector setup. Once you have found your desired setup I highly recommend you remove the levers one at a time and use non-permanent Loc-Tite to secure the retaining screws.

Some shooters have found that it may take a little more pressure to manipulate the fire controls. If you find this is the case for you then you can cut one or two coils off the detent spring to lessen the pressure on the KNS detent itself. I would not recommend this until after you have cycled the selector assembly at least several dozen times as it does smooth out some with use (mine took about 20 manipulations).

So is it the 45* ST for everyone?
In the end the Battle Arms 45 ST really delivers with its smooth operation and robust design and has a very positive and solid feel compared to a standard selector assembly. The levers tactile grip will help whether your hands are cold and wet from being out in the elements, slick from sweat, blood or mud or even while wearing gloves. I find I can simply push down on the Short Throw levers from either side and get a very positive ‘click’ as it locks down into the fire position with no wasted movement or mushy feeling on the controls. The whole system is simple to install and can be done in less than 30 minutes even with the modification to remove the pin. Top that off with the fact that it is ambidextrous which provides universal controls for shooting left or right handed. So if you are looking for a high quality, rock solid ambidextrous selector system in a unique, fast functioning short throw setup, check out the Battle Arms Development 45* Short Throw Selector.

Rainier Arms is also an authorized distributor for Battle Arms Development