With the popularity of InRange TV’s WWSD project, more people are interested in CAV-15 receivers than ever before. To combat misinformation and guesses people are posting on message boards and chat rooms, here are the tech notes on assembling and working on CAV-15 MKIIs. I wrote all this when I worked at Cavalry Arms Corp from 2001-2010. This is the correct the information direct from the source.

Assembly Video On Gunstreamer
https://gunstreamer.com/embed/nMKmHrwXcXKrKtv

. Notes to Gunsmiths and Armorers:

* Takedown Pins: Use the supplied speed pins to secure your upper receiver to your CAV-15 lower receiver. If you lose or misplace the supplied pins, replacement pins can be ordered from Cavalry Arms at a cost of $5.00 a piece.

* The CAV-15 MKII lower receiver uses a carbine buffer and spring.

* The CAV-15 MKII lower receiver uses standard mil-spec fire control pins. Though the area of the receiver that accepts the hammer pin is wider than aluminum AR15 receivers, it uses a standard fire control pins. Simply center the pin in the hole, and ensure it catches on the J-pin in the hammer.

* Check all pinholes before you Assemble gun! Parts vary slightly between manufacturers and some parts may fit tighter than others, especially the safety selector detent.

* Safety selector detent pin/spring load from the top. The spring may need to be trimmed for proper fit. The top of the detent should sit at 0.20” (+/- 0.020) from the base of the selector hole.

* Bolt hold open spring will need to be trimmed 1 to 1½ coils for the last round hold-open to function with older/weak magazines.

* The 5/64th roll pin attached to this sheet is to capture your buffer detent pin and spring.

CAV-15 Technical Notes

·If the Safety Selector Detent will not fit into the hole for the selector spring and detent, this is usually because the base of the detent itself is too wide. The base can be cut or ground off to fit.
·Selector spring and detent load from the top. Selector then slides over.
Note: Selector does not need to ever be removed. Fire control parts can be installed and removed with it in place. Before inserting selector check spring tension and trim spring if needed. Safety can be removed by placing half way between safe and fire and pushing out.
·The fit of the take down pins on the CAV-15 is intentionally tight. This is intended to keep the upper secured to the lower. The pins may require the use of a rubber hammer and punch to remove. The fit will wear in over time the more the rifle is disassembled for maintenance.
·If your magazines do not drop free from your lower, and you have verified that they are good magazines follow these instructions:
1.Separate the upper from the lower.
2.Looking down from the top into the lower, look to see where the mags are dragging with a magazine inserted.
3.Use a safe edge file to remove material from the mag well in the tight areas until the mags drop free.
4.Check for dropping free frequently so you do not remove too much material.
·If the buffer detent roll pin does not line up properly when hammed in to the lower, try inserting it from the opposite side to remedy the problem.
·If the buffer detent does not sit high enough to capture the buffer, it can be fixed by relieving material from the shoulder of the detent to allow it to sit higher.

CAV-15 .45 ACP Technical Notes

·You will need the following parts to build a .45 ACP CAV-15 Carbine
1.Complete CAV-15 MKII Lower
2.Olympic Arms .45 ACP Upper
3.Hahn Precision M3 Grease Gun Magazine Block
4.Heavy 8oz+ buffer (Hahn Precision or Slash)
5.M3 Grease Gun Magazines
·Failure to use the heavy 8oz+ buffer will result in damage to the lower
·M3 Grease Gun Magazine Fit:

The CAV-15 MKII has the center of the magazine well wider to be capable of accepting grease gun mags. We designed this feature based on some USGI surplus mags we had at the time (2003). Recently new batches of magazines have surfaced and there are manufacturers making new M3 Grease Gun Magazines. These magazines appear to be dimensionally different than the older USGIs we have. Users have started to encounter problems with these magazines in the CAV-15 lower.

If your M3 Grease Gun magazines are fitting too tightly into your lower, do not force them in. Doing so risks damaging the lower. Fortunately, the CAV-15 receivers’ construction lends itself to end user fitting and modification. The area that is too tight is usually the very front of the mag well where it is narrow for .223/5.56mm mags.

1.Separate the upper from the lower.
2.Looking down from the top into the lower, look to see where the mags are dragging with a magazine inserted (do not insert the mag all the way if it is tight).
3.Use a safe edge file to remove material from the mag well in the tight areas until the mags move in and out frequently
4.Check the fit frequently so you do not remove too much material.
5.Magazines themselves can also be fitted depending on the area that is dragging in your lower.

CAV-15 MKII Armorer Instructions.

Secondary Finishing (Post Vibration Welding)

These steps should be done at the factory, this is for reference in case they are not.

Trim all excess flash

Chase all holes
·Bolt Catch Detent
·Bolt Catch Cross Pin
·Buffer Detent and Cross Hole
·Safety Detent
·Front/Rear Take Down Pins

Assembly
Differences between CAV-15 MKII Receiver and standard aluminum receiver.

·Selector spring and detent load from the top. Selector then slides over.
Note: Selector does not need to ever be removed. Fire control parts can be installed and removed with it in place. Before inserting selector check spring tension and trim spring if needed. Safety can be removed by placing half way between safe and fire and pushing out.
·Safety Detent may need sizing
·Hammer pin will be recessed on both sides of hole. Insert until “J-Pin” engages center notch.
·Bolt catch may need spring trimmed to ensure proper tension.
·Take down pins are intentionally tight. Pins insert left to right into the receiver and are not captured in the receiver. Long pin in front, short pin in rear.
·Buttplate and Trap Door
Top Screw ¼-20×1”
Bottom Screw 10-32×1”
·Calibers larger than .223 will require 3H or heavier buffers. Unlocked blowback pistol caliber uppers must use appropriate weights (9mm 5.5oz, .45 8 oz. Or heavier to avoid damaging the lower)
·Buffer Detent is held in by 5/64thx1” Roll Pin (Buffer Detent Assembly is not needed for function of the rifle)

Parts Needed to Complete Lower:
1 Carbine buffer and spring
2 Hammer/Trigger pins
1 Hammer with spring
1 Trigger with spring
1 Disconnector with spring
1 Bolt catch with roll pin
1 Bolt catch detent with spring
1 Safety selector
1 Selector detent with spring
1 Buffer detent with spring
1 5/64thx1” Roll Pin
1 10-32×1” Flat Head screw
1 ¼-20×1” Flat Head screw
1 Mag Catch with button and spring
1 Long ¼” Speed Pin
1 Short ¼” Speed Pin
1 Butt plate with trap door assembly

Tools for assembly and armorer level repair:

Roll Pin Driver 5/64”
Roll Pin Holder 5/64”
Hammer
Razor Knife
Small file (safe edge)
Diagonal pliers
#24 Drill bit (bolt catch detent)
#27 Drill bit (safety detent)
¼” Reamer (take down pins and buffer detent)
5/64” Drill bit (buffer detent cross pin)
1” ½ Round file
#40 Aircraft drill (bolt catch cross pin)
6/32” Allen Wrench
1/8” Allen Wrench

Receiver Construction
·Nylon 6 30% Glass filled
·Linear vibration welded