Hoffman Tactical – Super Safety FAQ
General FAQ
Do these fit in all AR-15s?
They should. There is no guarantee, but as long as it is made according to mil-spec, it should fit fine. There are some high shelf lowers that need to be machined/dremeled open to allow clearance (Colt is the most notorious, but some others may be high shelf or have blocks, please see below). There are many uppers that almost clear the lever, but usually require a Dremel to cut the upper pocket back to the locking lug (see Modifications on our Install Page). You will likely need to go from a H buffer to H2 or H3 for reliability if you get light primer strikes/hammer follow.
What does D2, A2, S7, 4140, etc. mean?
The original design from Hoffman Tactical was for these parts to be 3D printed. However, currently available 3D printing materials only last for 2-400 rounds (up to ~1000-1500 on 316L in our testing), so companies have started to CNC the design out of stronger materials.
The most common and cheapest option is 4140 steel, it offers much higher durability than 3D printed options (we’ve seen deformation in the 5-10,000 round range), typically has a good appearance, and can be hardened to 640-750 Vickers HV (depending on the heat treat process and supplier) - Vickers HV is a measure of hardness, similar to HRC.
There are higher grades of steel, typically referred to as “tool steel” since they are used for tools such as cutting bits, stamping dies, etc. where they are subjected to high amounts of pressure, wear, impact, etc. repeatedly. Most of these materials will last in the 10s of thousands of rounds and long outlast the barrel, BCG, and likely the lower that they’re installed in. They each have different pros and cons:
D2 Tool Steel - High wear resistance, low-mid toughness, and medium compressive strength. This makes it a very ideal material for the Super Safety cam as it constantly rotates back and forth during operation, but makes it less than ideal for the lever as it’s subjected to impact by the BCG repeatedly which can lead to premature failure when the top of the lever breaks off. Typically heat treats to 750-800HV.
A2 Tool Steel - Medium wear resistance, medium toughness, and medium compressive strength. This makes it an ideal material for the Super Safety lever as it is subjected to both wear (along the underside of the BCG) and impact (as the BCG hits it going back and then again going forward). Typically heat treats to 710-800HV.
S7 Tool Steel - Low wear resistance, HIGHEST toughness, and medium compressive strength. We do not use S7 in our kits as we do not quite need the toughness it provides at the significant sacrifice to wear resistance (if D2 is a 5.5/10 on wear resistance, S7 is a 1.5/10). It will still work for a long time in a Super Safety system, but it is less than ideal in our opinion (though as a lever, it would work decently well, the top may just wear out before other materials due to the BCG). Typically heat treats to 650-750HV.
CPM-10V Tool Steel - HIGHEST wear resistance, low-mid toughness, and medium compressive strength. This makes it the ideal material for the Super Safety cam for the same reasons as D2 above, but on a scale of 10 this is a 8-10/10 and D2 is a 5/10 for wear resistance. Once you factor in the additional wear resistance from coatings, it would exceed the scale of 10. The downside to CPM-10V is the very high cost, even compared to other tool steels. Typically heat treats to 750-870HV.
Why should I buy your kit versus XYZ Inc or ABC Corp?
A good question. There are a variety of manufacturers out there offering super safety kits in varying materials and finishes at a wide range of prices. We simply strive to offer the best option between the materials used, the tolerances during machining, the finish used, and our experience running them in our personal platforms. We were the first to offer D2 Tool Steel kits, long before AS Designs existed. We were the first to use A2 Tool Steel levers to prevent premature failures we saw in testing and early products. We continue to look for new materials that can offer an even higher level of quality for our customers. We do not expect to capture every single customer that exists for this product and that is okay, competition is ideal for everyone. That said, we are friends with many of the other manufacturers and support them directly and indirectly since day one.
How do I make this fit in a MP5/SP5/clone?
You will need to purchase or 3D print a lower that accepts AR FCG and controls. We typically recommend Polymer Pew or SkoPrints as they utilize designs based on the ARMP5v2 lower from s3igu2. You can also use Lee Sporting lowers, but you may run into some compatiblity/fitment issues as it was not designed for the Super Safety. You will also need a "slip trip" that many places offer (including us, HERE) or you can 3D print, do NOT use the V1 steel trips, ensure it is a lightweight (V2 and V3) steel trip or aluminum trip (heavy trips can break the lever). Verify weight is under 25g, below are typical weights:
V1 CF Nylon - 6g
V1 4140 - 42g
V3 7075 - 8g
V3 316L - 20g
V3 4140 - 21g
Do these have more than two positions?
Yes, they have semi, super safe, and safe (see positions on our Install Page).
Are these legal?
According to current legislation and federal court, yes. This requires a single action of the trigger for each shot fired, then the BCG forces it into safety which resets the trigger moving it forward, then the BCG moves it back out of safety as it chambers the next round, then the trigger may be activated again. These mechanically function differently than RB or WOT FRTs (they reset via the hammer), so they can't fully be classed together, but the end result is similar enough that legislation can apply equally. Additionally, the recent federal court ruling against the ATF has defined that FRTs are NOT machineguns (National Association for Gun Rights, Inc. v. Garland (4:23-cv-00830)). Now if you live in a state with laws against FRTs, you can't possess this (look up your own laws please, but it should be FL, CA, CO (Broomfield and Boulder County), CT, DE, HI, IL, MD, MN, NJ, NY, and RI that have laws against them). Also, please respect any ranges that you visit that may have rules against these.
What lowers have high shelf or low shelf?
The below lists are not set in stone and you should double check your own part.
Low Shelf:
Aero "Clone" Lowers (Recent change, older may be High Shelf)
Aero Gen2 and M4E1
Aero Precision Gen 2 Model X15
Ameetec Arms
Anderson Manufacturing (Varies, but typically lower)
Anvil Arms
Barrett
Bravo Company (BCM4 almost Colt SP1/A2 dimensions)
Bushmaster
CMMG
Colt (Legacy/SP1)
Colt (Preban)
Colt AR-15 A2 Gov't Carbine Pre Ban
Colt AR-15 A2 Hbar Sporter Pre Ban
Colt SP1/A2
Colt Sporter II
Daniel Defense
DoubleStar
DPMS (Varies, may be high shelf)
Essential Arms J-15
FN Commercial Lowers
H.S.
KAC Stripped (Non-Ambi)
LAR
LMT (Varies, may be high shelf)
LWRC (5.56 Ambi Version)
Mega Machine
New MGIs
Nodak Spud Retro
Noreen BBN-223
Noveske N4 Gen1 X Series (Colt SP1/A2 Dimensions)
Olympic Arms
Palmetto State Armory (Varies, but typically lower)
Patriot Ordnance Factory
Quentin Defense
Rock River Arms LAR-15
Seekins
Sendra
Sharps
SI Defense
Spikes (All 5.56 Models)
Vulcan
ZEV
Zombie Defense
M16 Cut (Same as Low Shelf, but requires centering block):
Alexandria Pro Fab
BCI Defense
Black Creek Precision
Centurion CM4
DS Arms
East Lake Industries LLC
Expo Arms
Geissele
Griffin Armament
IWI
LWRC (Varies, may be low shelf)
Matrix Arms
Modern Armory
Mrgunsgear
Presample Depot
Primary Arms
PWS Mk1 Mod2
Radical Firearms
SAA Mfg
San Tan Tactical
Serbu Lowers
Shadow Ops Weaponry
Sionics
Sons of Liberty Gun Works
Standard Mfg
High Shelf:
ABC lowers
Alexander Arms
Colt (Current Production) - High Shelf w/block
Delton
KAC Ambidexterous
LMT Mars L
Stag Arms