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Griffin Armament SN-ACH Charging Handle

10/30/15 - The SN-ACH (Suppressor Normalized Ambi Configurable Handle) from Griffin Armament is an ambidextrous charging handle for the AR15 and AR10 with user-configurable levers and a gas vent that reduces gas in the face of the shooter when using a suppressor.

Background - As a left-handed shooter, I've been delighted over the past few years to see the availability of ambidextrous controls for the AR15 steadily increase. While we still live in a right-handed world, there's no reason why our weapons have to. Ambidextrous controls are more the standard than the rarity on the newest weapons, and it's good to see the AR15 get an update. The offering of ambi controls for the AR15 have given the design greater longevity and relevance than ever before as it now caters to both left and right-handed shooters.

For those who don't use suppressors, gas in the face isn't an issue. But for those who do, gas can be an issue, especially when the gas starts stinging the eyes. I've shot full auto SBR ARs with suppressors before, and got a nose-full of acrid gas with each burst, and stinging eyes. I'm a lefty, however, so I'm getting the full blast of any gas drifting back from the ejection port. Gas escapes out of the receiver any way that it can; above and below the charging handle, between the upper and lower etc. PRI came out with their 'gas buster' charging handle years ago, which features channels to divert gas out of the right side of the upper receiver. The Griffin SN-ACH takes these two ideas (ambi and gas diverting) and marries them into one product.

Description - The SN-ACH is made of 7075-T6 aluminum and features a gas check groove and suppressor gas vent/port that is designed to reduce the amount of gas hitting the face of the shooter when using a suppressor. The hook that engages the bolt carrier features reinforced geometry for a 30% in strength over the milspec handle; there's a web that connects the shaft and the hook, similar to that on the PRI Gasbuster. The SN-ACH has configurable levers so that the user can choose to run the standard (long) levers, or purchase the shorter ones separately. I prefer to use a combination of the two - long lever on the right (I'm a lefty) and short one on the left; since I pull back the charging handle with my right hand. The handle and levers are hard coat anodized for optimal wear resistance.

The back of the handle has a gas-check groove on the bottom, which is supposed to help reduce the gas blowing by on the bottom of the handle. Without an actual flexible seal, I'm not sure how effective it would really be. There are a couple of fitting pads on the top of the handle behind the hook, which help keep the charging from wobbling in the receiver. Two T10 torx screws serve as the lever pivots, and when removed, allow the levers to be swapped out, as well as the spring. The first run of SN-ACH handles had a spring that was too weak, and some customers had the latch hook 'jump the groove' on the receiver when shot. Griffin shipped out replacement springs which addressed the issue. All current production SN-ACHs have the stronger spring.


Standard (long) levers

Gas vent

Shown here are both versions of the SN-ACH, in an AR-15 and AR-10 (.308). One thing I did notice was that there was slight contact with the adjustment wheel on my Troy folding rear sight. Nothing that interfered with the function though. So, do keep that in mind when pairing the SN-ACH with your rear sight. I found that rear sights that don't hang below the level of the upper receiver flat top work best.




Contact with rear sight

Notes/Observations - The Griffin SN-ACH is well made; I noticed that the finish seemed a bit smoother than some other charging handles. This translates to nice and smooth operation in the receiver. I always oil the charging handle before installation as well, but some charging handles feel like they drag more. I like a combination of the long and short levers as I seldom use the lever on one side. I found swapping levers to be relatively easy. I was able to compress the spring and hold the lever in place with one hand while the other inserted the screw and tightened it. The latches feel comfortable and secure when using a pinch hold to draw the handle rearward; both with and without gloves.

Since I don't currently have the opportunity to shoot suppressed, I didn't have the chance to see whether the gas-reduction features really work. Griffin estimated the effectiveness of the gas port to be around 40%. It doesn't eliminate gas in the face but does reduce it. A silicon seal would probably reduce it further but would add complexity/parts to the design. Plus, a silicon seal would be a wear item. Since the gas port vents gases out of the right side of the handle, it's not really designed for a lefty shooter like me (for use with a can, that is). So, I'm not sure I'd recommend it for a lefty shooter using a suppressor; just based on the design. If someone has experience with this and finds otherwise, contact me to let me know. As a regular ambi charging handle for left-handed, non-suppressed use, it works very well (or for right-handers of course, both suppressed and non-suppressed).

Short vs long lever

Short lever on left side



BCM PNT Trigger Assembly and Enhanced Lower Parts Kit

2/6/16 - Bravo Company USA has introduced the BCM PNT Trigger Assembly (Polished - Nickel - Teflon) and BCM Gunfighter Enhanced Lower Parts Kit. The Lower Parts Kit features the PNT Trigger Assembly along with all U.S.-made components.

Background - An AR-15 LPK (Lower Parts Kit) contains all the necessary parts (fire control group, springs, pins etc) to complete a stripped lower receiver; except for the stock/receiver extension assembly. LPKs are available from a number of vendors and manufacturers; some with known pedigrees, and others with 'generic' parts of unknown origin or quality. BCM's parts are all made in the U.S. and the customer can be assured of quality components. I typically buy lower parts kits minus the trigger and hammer assemblies, grip and safety as I typically don't use the USGI versions of those components, but for the customer who prefers a better-than-'USGI' kit, the BCM Enhanced LPK is a good choice.

PNT Trigger Assembly - The PNT Trigger Assembly consists of the BCM PNT hammer and trigger, hammer and trigger springs, the pivot pins, disconnector and disconnector spring. 'PNT' refers to Polished, Nickel and Teflon. The PNT trigger and hammer are machined from Mil-Spec AISI8620 investment castings per the USGI TDP. These are not to be confused with MIM parts commonly found in the commercial market. The .156/.157 holes are honed to assist in alignment and a smooth trigger pull. Both parts go through a 3-step heat treat and case hardening process for optimal grain structure alignment, for strength and wear resistance.

Polished - The sear engagement surfaces are ground, then hand polished for increased smoothness and reduction in friction up to three times beyond the Mil-Spec.

Nickel - This is what gives the parts their silver-grey finish. An electroless nickel finish is applied for a smoother trigger pull with reduced felt creep and grittiness. Nickel also provides a long lasting, corrosion and rust-resistant finish. Both the trigger and hammer have BCM's star logo on them for identification.

Teflon - Teflon particles are embedded in the nickel, further reducing friction and ensuring a long-lasting coating.

The hammer and trigger pins are centerless ground to a fine finish and toleranced to ensure compatibility with all Mil-Spec lower receivers. The BCM Disconnector is stamped from a 1070 material and fine blanked for cleaner edges, and double disc ground to precise size. Hammer engagement surfaces are ground for a clean reset.

PNT trigger kit

Standard hammer/trigger in lower as reference

PNT kit installed in same lower

BCM Enhanced Lower Parts Kit - The BCM Enhanced Lower Parts Kit includes the PNT trigger/hammer assembly and all the other parts (excluding the receiver extension and stock) necessary to complete a stripped lower receiver. LPKs include your choice of BCMGunfighter Grip Mod 3/trigger guard colour (Black, Flat dark earth, Foliage green or Wolf gray).
The BCM Enhanced Lower Parts Kit includes:

1. BCM PNT™ Hammer
2. Hammer Spring
3. BCM PNT™ Trigger
4. Trigger Spring
5. Hammer/Trigger Pins
6. Disconnector
7. Disconnector Spring
8. Bolt Catch
9. Bolt Catch Plunger
10. Bolt Catch Spring
11. Bolt Stop Pin
12. Rear Pivot Pin
13. Buffer Retainer
14. Buffer Retainer Spring
15. Magazine Catch Button
16. Magazine Catch Spring
17. Magazine Catch
18. Rear Take Down Pin
19. Selector (Safety)
20. Selector Detent
21. Selector Detent Spring
22. BCM Enhanced Trigger Guard
23. BCM Trigger Guard Pin
24. BCM Trigger Guard Screw
25. BCM Pistol Grip Mod 3, Grip Screw, Locking Washer
26. Take Down/ Pivot Pin Detent
27. Take Down/ Pivot Pin Detent Spring

Where applicable, parts are made from alloy steel put through a 3-step heat treat and case hardening process, and ground for precision. Takedown detents have a cadmium chromate coating to resist corrosion and prevent them from seizing in the small lower receiver holes. Springs are 17-7PH stainless steel.


LPK small parts

Notes/Observations - The PNT Trigger and Enhanced Lower Parts Kit offer high quality at a reasonable price. The PNT Trigger bridges the gap between a USGI trigger and a specialty after-market trigger like a Geissele. The PNT retains the reliability of a mil-spec set up while reducing the creep and grittiness present in the standard trigger setup. When I refer to 'USGI', I mean good-quality mil-spec parts; not the cheap commercial gun-show parts bin types. When new, good quality triggers from Colt and LMT for example, will still have noticeable creep until many rounds later when the mating surfaces have smoothed out somewhat. The PNT trigger assembly bypasses that 'break-in' period.

I used my Lyman digital trigger pull gauge to take some measurements. For an LMT trigger assembly that I hadn't done anything on, I measured between 8lb 6.5 oz and 8 lbs 14 oz. For one that I had done a home trigger job on (polishing mating surfaces carefully), I measured a pretty consistent 6 lbs 13.5 oz. I installed the PNT trigger assembly into a lower and took multiple measurements on the PNT trigger (I used some grease on the hammer/trigger engagement surface as I normally do when assembling lowers) and readings ranged from 6 lbs 6oz to 6 lbs 12 oz; with most hovering around 6 lbs 10 oz. Creep was barely noticeable; I didn't feel any grittiness in the pull. It felt pretty smooth all the way through. Reset was also crisp without grit.

I examined all the other small parts in the kit and they looked like good quality stuff, as I'd expect from BCM. I'd like to see an Enhanced kit packaged without the grip or trigger guard, as grip choice is personal and I don't use grips with a backstrap (short fingers). Many of the newer lowers have integral trigger guards as well. I always like to have a few LPK's around as spares; but they always seem to disappear into new lowers. I'm sure that BCM's offerings will be a very popular choice when it comes to buying LPKs to complete new lowers.



Arisaka Defense Low Profile Picatinny Rails

1/13/17 - Featured here are the Low Profile Picatinny Rails from Arisaka Defense. They're available in both KeyMod and M-Lok options.

About Arisaka - Arisaka LLC is a small design/manufacturing company, named in honor of Arisaka Nariakira, inventor of the Arisaka rifle. Its Japanese American founders chose the name to honor their cultural background and show respect for one of Japan's most iconic weapons designers. Both shooting enthusiasts, they channel their creative energy into creating unique and well-engineered components and accessories for the shooting industry. All Arisaka products are designed, prototyped, manufactured, assembled and sold exclusively within the USA. The rails are CNC machined from 6061 aluminum and Type III hard coat anodized.

Background - The specs for the 1913/Picatinny rail call out different dimensions, one of which being the overall height of the rail. This is to ensure that there is a minimum 'standoff' height that provides clearance between the rail and the base (handguard, receiver etc) for clamp mounts or 'rail grabbers'. The thickness of the clamp can vary, as long as it doesn't exceed the standoff height. Not all; in fact many 1913 accessory clamps don't make use of the full standoff height, and therefore don't need a full thickness rail to mount to. That way, they can be mounted closer to the handguard. This is mainly applicable to handguard-mounted 1913 accessories. The total height of the 1913 rail from the top to the mounting surface is specified at .367" minimum. The Arisaka rails are .277" tall, reducing the height by .090".

Shown below are a couple of examples of vertical grips with different clamp thicknesses. The KAC grip to the left is less 'beefy' than the TangoDown one on the right. The Surefire X300 and INFORCE WML have clamps that come to points, which need very little standoff height. Comparing the BCM accessory rail, which is made to 1913 spec and the Arisaka Low Profile rail, you can see the difference in standoff heights (the distance between the red arrows).

KAC and TD vertical grips

Surefire X300, Inforce WML

BCM (R) and Arisaka rail (R)

KeyMod Low Profle Rails - The Low Profile Picatinny Rail KeyMod is offered in 5 and 3 slot (not shown here) options. It has three of BCM's patented reverse threaded KeyMod screws which attach it to KeyMod handguards and two recoil lugs. The 5-slot rail is 2.15" long and weighs only 0.6 oz. It requires a T15 Torx wrench (not included) for installation. I've illustrated the Arisaka rail below alongside the BCM rail; mounted to a couple of different handguards (BCM KMR and Vltor VIS-KM). The low profile rail is most useful for bringing items like the X300 or vertical grips closer to the handguard.

KeyMod 3 slot

KeyMod 5 slot

Compared to BCM

BCM and X300

Arisaka and X300

M-Lok Low Profle Rails - The Low Profile Picatinny Rail M-Lok is also offered in 5 and 3 slot options. The 3-slot rail has two M-Lok nuts and the 5-slot rail has three nuts. The 5-slot rail is 2.15" long and weighs only 0.7 oz. It requires a 1/8" Allen wrench for installation (not included). Both 3 and 5-slot M-Lok rails are illustrated below on a KDG SCAR handguard, and compared to the Magpul M-Lok rail.

3 and 5 slot M-Lok

3 slot on SCAR

5 slot

Compared to Magpul rail

I tried out some different accessories on the low profile rails; like Surefire and WML lights, rail-mounted bipods, vertical grips etc and didn't find anything that wouldn't fit. I'm finding the low profile rails very useful for mounting a bipod to the handguard. For rifles that I don't normally have bipods mounted to, I do like to use a bipod temporarily when sighting in or confirming zero at the range. The 3-slot rail is perfect for that purpose. I've illustrated it below mounted midway along a KMR handguard. The Bobro bipod legs fold alongside the Arisaka hand stop. I've also found the old Grip Pod very convenient to use as well, just for zeroing. It's too ungainly to keep on the rifle normally. The rails are also unobtrusive mounted near the front of the handguard, and so light that I don't notice they're there. Again, perfect for a bipod mount and I prefer the Bobro to stud-mounted Harris bipods.

As for reducing bulk, a .090" reduction might not seem like much, but when applied to the width of a handguard and accessories sticking out, it does make a difference. Like all of Arisaka's products I've seen, the rails are well designed and made.

Mid-mounted 3 slot on KMR

Bobro bipod

Grip pod

Front mounted 3 slot

Front mounted 5-slot on SCAR



Battle Arms Development RACK Charging Handle

1/19/19 - BAD (Battle Arms Development) in Henderson, NV, has released their RACK ambidextrous charging handle for the AR15. It was designed with asymmetric charging in mind, and has a latch that slides to the side instead of one that pivots on a roll pin.

Background - Known for their BAD-ASS ambi safeties and envelope-pushing designs, BAD's RACK charging handle concept was actually conceived of quite a few years ago, but put on the back burner to work on other projects.

With the RACK, BAD felt that their design could address some areas in which they felt needed improving; namely:

  • Elimination of roll pins - roll pins can be a weak link in the system
  • Non-Pivoting latch - BAD felt that a side-sliding latch design that moves parallel to the upper receiver notch wall works better than a pivoting/rotating latch to minimize notch wear from the hook.
  • Handle strength - With many people utilizing an assymetric pull on the charging handle, BAD wanted to ensure that their handle/latch design was robust. Instead of separate left and right latches attached to the body, they instead went with a monolithic (one-piece) latch
  • Finish - One of the things that BAD noticed on many charging handles was that when new, the shafts would feel a bit gritty in the upper receiver channel when brand new, and the anodizing would wear off the contact surfaces. They tried different permutations of tumble, bead blast and anodizing thickness to provide a smoother pull and more durable finish that doesn't wear off as quickly.
  • Secure locking - The RACK charghing handle is designed to stay put and not bounce or unlock during recoil.

Description - The RACK is CNC'd from 7075-T6 aluminum and is coated in a hard anodized black finish. The RACK, for the most part, looks like a pretty standard ambidextrous charging handle, with a slightly longer (front to back) skeletonized handle/latches. Closer examination reveals that the symmetrical 'T' handle is a single piece, rather than two latches or handles that pivot on the main body. The handle is attached to the main body with two screws, which also act as pivot/slide points. The bottom of the main body is T-shaped, and has two slots in which the heads of the screws can slide in. By pulling on either side of the handle, it will pivot on the opposite side screw and the latch/hook will slide to the side, so it clears the notch in the upper receiver. BAD has patented their mechanism.

Inside the body, there are two springs which provide spring tension on each side of the handle. Pulling back on either side of the handle compresses the spring on that side, and pulling equally back on the handle compresses both springs. Pulling straight back on the handle to unlock the latch requires overcoming both springs. Either way will cause the latch to slide to the side. Without pulling on the handle at all (like when the charging handle returns to the forward position), the latch will pivot when the hook encounters the rear of the receiver notch ramp; not slide.


Bottom view

Sliding latch/hook (does not pivot)

Shown below is the RACK compared to the Raptor and BCM GUNFIGHTER Gen 3 charging handles, for handle/latch size comparison. The RACK extends to the sides the same amount as the longer handles on the BCM and Raptor. Being a solid piece, you can't swap out longer or shorter left or right latches (unless BAD eventually offers them). The main difference in look is that the RACK handle extends further back than either of the other two charging handles (in line with the rearmost point on the back of the lower receiver), and the parallelogram-shaped 'ears' are larger since they don't taper towards the end.

With Raptor and BCM gen 3 handles

Handle comparison (Raptor and BCM)

Notes/Observations - As mentioned above, the RACK handle looks bigger than other popular charging handles because of the larger handle that extends further to the back. Aesthetically, I'd prefer the handle to be a bit more low profile, and taper towards the ends. Functionally, the larger handle is very comfortable to grab with or without gloves. Manufacturing quality is what we've come to expect from BAD - excellent. The finish on the shaft is smoother making for a smoother operation in the upper receiver channel.

Operation of the RACK charging handle is the same as most other ambidextrous charging handles, but not quite the same as the standard USGI handle. The RACK is designed for assymetric operation by pulling either the left or right side of the handle, allowing it to rotate and slide the latch hook out of the way of the receiver notch. When used as designed, operation is smooth and easy. If I use my index and middle finger on both sides of the handle and pull straight back equally (or any other method to pull back perfectly equally on both sides), the latch hook would hang up on the receiver notch. This is because pulling equally compresses both springs, and combined, they have more spring force than the buffer recoil spring in a carbine. I can use the two-finger pull method; but had to make sure that I rotated the handle to either side a bit so the hook cleared the receiver notch before pulling back; then after it's cleared, equal pressure can be used to pull it all the way rearward. The other thing I noticed was that if I used the two-finger method; the left finger would prevent the latch hook from sliding to the left, causing it to hang up on the receiver notch. Just bear this in mind when using the RACK. I estimate that the handle needs to rotate about 75% of its full angle for the latch hook to completely clear the receiver notch.

The upside to this design is that the latch is less likely to 'jump the notch' due to recoil. Since most other charghing handles open the latch hook when either side of the handles is pressed, sometimes the recoil will cause the latch to unhook due to the backwards inertia of the handle. Fixes have been to put stronger springs in the handles. With the RACK, straight back recoil is less likely to unlock the latch because it would have to overcome both springs holding the handle forward. The requirement to rotate the handle to prevent latch hook/receiver notch wear will work, as long as you remember to do that. I'm guessing that some may not always remember, so whether this design actually reduces the chances of receiver notch wear will depend on what the user is used to.



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