Black Rifle Arms Operator Manual for L.P.R.D.I. System by blackriflearms.com

1. Low Profile Regulated Direct Impingement System
(L.P.R.D.I.)
Operators Manual

2. Low Profile Regulated Direct Impingement System Nomenclature
2
Gas Block
Regulator
Knob
Position
Indicator
Takedown Pin
Bolt Assembly
Cam Pin
Bolt Carrier
Bolt Carrier Buffer
Gas Tube Compression Nut

3. 3
ADJUSTING THE LOW PRO REGULATOR
Figure 1 shows the position indicator on
the ejection port side indicating the
regulator is in the silencer setting. This
position reduces gas flow to compensate
for silencer back pressure.
Figure 1
The following instructions are to be referenced from the shooters perspective. To rotate the regulator knob between the various gas
settings requires the operator to grasp the knob firmly pressing it forward until it’s interlocking teeth are clear then rotating slightly,
release forward pressure and continue to rotate until the knob auto locks into the next gas setting. The knob may be rotated in either
direction a full 360 degrees with four settings at 90 degrees apart. See figures 1 thru 6 below for setting specifics.
Figure 2
Figure 2 shows how an operator pulls forward
on the regulator knob to clear the locking
teeth allowing rotation of the regulator knob
between gas settings.
ALWAYS USE THE LOWEST GAS SETTING THAT WILL OPERATE RELIABLY WITH WHATEVER AMMUNITION IS
BEING FIRED, THIS WILL OPTIMIZE THE SYSTEMS PERFORMANCE AND MINIMIZE WEAR.
The regulator knob has a small hole and a large hole at its forward end. The large hole is the position indicator.

4. 4
ADJUSTING THE LOW PRO REGULATOR CONTINUED
Figure 3 shows the position indicator at the 12
o’clock position indicating the regulator is in the
normal gas setting. This is the setting for US
COMMERCIAL and US MILITARY ammunition
under normal shooting conditions.
Figure 4
Figure 4 shows the position indicator at the
shooter’s left or the 9 o’clock position indicating the
high gas setting. This setting is for adverse
conditions or light powered ammunition.
Figure 3

5. 5
ADJUSTING THE LOW PRO REGULATOR CONTINUED
Figure 5 shows the regulator in the off
position shutting the gas off stopping the
action from cycling and effectively
making the firearm a bolt action. Note
the position indicator is at the 6 o’clock
while the small hole is at the 12 o’clock.
Figure 6 shows how the regulator knob was
design so a bullet could be used to adjust the
regulator if heat or fouling makes rotating the
knob more difficult.
Figure 5 Figure 6

6. 6
Low Profile Regulated Direct Impingement System Disassembly
Figure 1) Push takedown pin thru
the gas block. A bullet, firing pin or
similar tool may be use for this job.
Figure 2) With the takedown pin fully
extended out of the gas block remove the
regulator by pulling it out thru the front of
the gas block.
Figure 2Figure 1

7. 7
Low Profile Regulated Direct Impingement System Reassembly
Figure 1
Figure 1) Insert the regulator thru the front of
the gas block. Be sure the locking teeth of the
gas block and regulator knob are seated flush.
Figure 2) Use your finger or an appropriate
tool and press the takedown pin in flush with
gas block. This completes reassembly.
Figure 2

8. 8
Low Profile Regulated Direct Impingement System
Always confirm that the firearm is unloaded before beginning disassembly. Start by removing the upper
receiver from the lower receiver. Remove the bolt carrier group and charging handle from the upper. Fig. 1
Figure 2
Figure 1
Remove the handguard retaining screws and remove handguard by pulling it forwards straight off the end of
the barrel. Fig. 2
Note: Handguards do not need to be removed to adjust or services the regulator, but may be removed
for detailed cleaning of the barrel and gas block area.

9. 9
Low Profile Regulated Direct Impingement System (L.P.R.D.I.) Features:
– 4 Position Regulated Gas System
– Pull Free Regulator
– Multi Regulator Design
– Ambi-Regulator Knob
– 360° Continual Rotation
– Easily Adjustable with One Hand
– Easily Adjustable with Gloves On
– Easily Adjustable from Firing Position
– Audible and Palpable Setting Confirmation
– No Detent Pin to Push In to Adjust Gas Regulator
– Regulator Knob Allows for Zero Visibility Adjustment
– Interlocking Mechanism Prevents Accidental Rotation of Knob
– Knob Configured for Rapid Adjustment with No Loss of Target Engagement
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Black Rifle Arms
New Smyrna Beach, FL
386.410.5162