In addition to the other two posts so far today, I am sharing another one of Hognose’s posts from Weaponsman.com. This is a repost in our ongoing commitment to honoring our dead friend Kevin and his work.
There are several kinds of safeties that are used on service weapons to ensure that only the proper and deserving people are shot. They generally interface in some way with the firing mechanism of the firearm. They may act on the trigger, the hammer or striker, or the sear, or (in some fiendishly clever arrangements) more than one of the above. It is generally thought better to positively lock the striker or firing pin than merely to lock the sear or trigger. If the mechanism fails due to parts breakage, it is easier to design a fail-safe mechanism if the striker or firing pin is immobilized.
Safeties Classified by Operator Volition
Safeties can be classified based on the degree of volition required to use them. An applied safety must be consciously put on, in most cases. An automatic safety is unconsciously applied as the pistol is taken up. Examples of automatic safeties include:
- the Glock Safe Action trigger and its many copies and derivatives;
- the grip safeties characteristic of many Browning designs, such as the M1911 .45 and the FN M1910 pocket pistol;
- similar grip safeties on open-bolt submachine guns such as the Madsen and the Uzi. (An open-bolt SMG poses peculiar safety problems);
- transfer-bars and other means to ensure a weapon can’t fire unless the trigger is pulled;
- mechanisms that hold a firing pin back until a weapon with a locking breech is fully in battery (the disconnector often does double-duty as this part);
- Firing-pin immobilizers as in the Colt Series 80 and newer M1911s (an earlier firing pin safety, the Swartz Safety, was used in commercial Colt 1911s from circa 1937 to 1940, and is used by Kimber today);
- A heavy, smooth trigger pull such as that on a traditional Double Action revolver or a DA/SA autopistol can prevent unintentional discharges. However, some heavy triggers (like the Glock NY2) have a bad enough effect on accuracy as to threaten bystanders with unintentional shooting.
- Magazine safeties, an obsolete European concept;
- Half-cock notches (in British/European English usage, these may be called half-cock “bents.”)
Contrasting with these automatic safeties, that do their work without conscious application by the operator, there are Applied or volitional safeties. Applied Safeties are usually classified by what part of the firing mechanism they work on, and so examples of Applied safeties break down into:
- Safeties that lock the trigger. The simplest of these are the crude trigger-blocking safeties on an SKS or Tokarev SVT. More complex trigger-locking safeties are found in the AR series of rifles and the FN-FAL;
- Safeties that lock the firing mechanism (which may be further divided into those that lock the firing pin, like the Walther P.38 or Beretta M92, and those that lock the hammer, like the US M1 Rifle, or
- The bolt holding notch in many 2nd-generation submachine guns. (These are reminiscent in a way of the safety of the Mosin-Nagant rifle, which requires the cocking piece to be rotated and caught in a notch). The case can be made that this is a firing mechanism lock, because the bolt with its fixed firing pin is the firing mechanism.
- Safeties that lock the sear. Examples include the .45 M1911, its younger brother the BHP, many other auto pistols, and most general purpose machine guns. Some require the weapon to be cocked to lock the sear, others allow locking the bolt forward (the RPD LMG and the Sterling SMG are examples of this).
- Safeties that disconnect the trigger from the sear. This is found in the Bren gun and many other Czech designs, historically. The ZB 26 and its derivatives were quite cunning: in one position, the selector brings the trip lever to engage the semi notch, which is in the upper side of a window in the sear. In the other position, it engages the auto notch in the lower side. In the intermediate, “safe,” position, the trip lever clears both notches and the weapon does not fire.
Note that automatic safeties, too, can be broken down as working on the trigger, the firing mechanism, and the sear, also. So safeties can also be Classified by Operation.
Safeties Classified by Operation
It is possible to classify safeties in the first place by their means of action:
- Trigger safeties
- Firing-mechanism (striker, hammer, firing pin) safeties
- Sear safeties
- Disconnecting safeties.
This is true, obviously, for both automatic and volitional safeties, and classifying them this way puts their mode of action forward as more important than their mode of engagement, which (applied/volitional or automatic) becomes a secondary trait.
One More Trait: Must the Firearm be Cocked?
It is only possible to engage many safeties when the weapon is cocked or ready to fire (presuming a chambered round). Familiar examples include the AR series rifles and the 1911 pistol and other Browning hammer designs. Other safeties engage regardless of the energy state of the striker or hammer, for example the AK, the Remington Model 8 (a Browning-designed trigger mechanism that was deeply influential on 20th and 21st Century firearms designers, including Garand, Kalashnikov and Stoner), and the RPD light machine gun.
While a weapon may have multiple safeties that do different things (or multiple modes that engage the same safety, as in the safety lever and grip safety of early Lugers), it’s possible for a single cunningly-designed safety to disable multiple points of the firing chain at once. For instance, the Lee-Enfield safety is a model of versatility: it locks the striker, locks the bolt closed (preventing the chambering of a round), and disconnects the striker from the sear. The M1911 or Browning High-Power safety locks the slide closed as well as locks
It’s also possible for a volitional safety to be combined with other functions. The most common example of this is the combined safety/selector switch of most modern assault rifles, like the M16 or AK-47.
To Sum Up
There are a great but finite number of ways to design safety features on modern firearms. Careful study of prior art allows today’s designer truly to stand on the shoulders of the giants in the field. John Browning left no memoir or technical book, nor did John Garand, John D. Pedersen, Gene Stoner; and the many memoirs of Mikhail Kalashnikov are disappointing to the technical reader. But each of these geniuses spoke to us in the art of his designs, and they are still available for us to study and to try to read what their art is trying to tell us.
We have not, in this limited post, attempted to discuss “best practices” or the pros and cons of any individual safety design. Very often, the designer will be limited by the customer’s instructions or specifications. (For example, the grip safety of the 1911, which 1970s and 80s custom smiths often pinned in engagement as a potential point of combat failure, was requested of John M. Browning by the US Cavalry. The other military branches didn’t feel such a need, but the horse soldiers did, and Browning first added it on his .38 caliber 1902 Military pursuant to a similar request). Thus, even as a designer, your safety design decisions may not be your own.
Notes and Sources
- This post has been modified since it was first posted, to expand it.
- This post will be added to The Best of WeaponsMan Gun Tech.
This post owes a great deal to the following work:
Allsop, DF, and Toomey, MA. Small Arms: General Design. London: Brassey’s, 1999.
Chapter 13 is an extensive review of trigger mechanisms, including safeties, and while their classification of safeties is different from ours, their explanations are clear and concise.
Thanks to the commenters who not only recommend this long out-of-print book, but also sent us a link to a bookstore that had it (it’s a copy withdrawn from a military library, as it turns out). This out-of-print work is less technical and deep, but considerably more modern, than Balleisen; its examples are primarily British.
Kevin was a former Special Forces weapons man (MOS 18B, before the 18 series, 11B with Skill Qualification Indicator of S), and you can expect any guest columnists to be similarly qualified. He passed away early last year.
As you know, we here at LooseRounds.com like to stay pretty informal. We previously encouraged people to send us guest posts, but almost every week now we get sent some absolute garbage.
One example, we had someone submit an article, “Glock 42 V.s Desert Eagle: Which Is Best Suited For Military“. This wasn’t even a parody. The intro picture was of a blank firing Beretta clone. Phrases like, “Stops power” and “Handguns continuous inventions fail to include distinctive features.” were used much like how we butcher the English language.
I contacted the writer and told them that if they had written that sober, they should go see a doctor in case they had suffered a stroke. Hell, if we wanted something written that poorly, I’d write it myself.
Around a decade ago it was common knowledge that Eotechs were faster to use and better than Aimpoints. Just like how not very long before that it was common knowledge that the Earth was flat.
The Eotech sights use a laser to project a hologram of the reticle in the optical window. This allows for a greater variety of reticle patterns then a diode sight like the Aimpoint. Most common in Eotech sights are a 1 MOA dot with a 65 MOA circle around it. A downside to holosights are shorter battery life. Battery life on the Eotech is advertised to be about 1000 hours.
There are other variations with additional dots to function as a drop chart. There are also machine gun reticles.
For the life of me, I could not get the reticle to show up nicely in a picture. Despite how it looks in the photo, the reticle is bright and easy to see. If you focus on the reticle, you will see that it is comprised of a bunch of dots, it will appear to be fuzzy if you have the brightness cranked up. That is just due to the nature of how it works.
Windage and Elevation is easy to adjust using a coin or similar tool. Both adjustments have positive clicks and are easily accessible on the right side of the sight.
Brightness is adjusted using the up and down arrow buttons on the rear of the sight (there are some models where the adjustments are on the left side of the sight). If the sight is off, hitting one of these buttons will turn on the sight.
The Eotech will automatically turn it self off it preserve battery life. Turning it on by hitting the down button will have the Eotech turn off after 4 hours. Hitting the up button will have it off after 8 hours. Holding both buttons will turn the Eotech off immediately.
Some models, like this 553 have a NV button that will dim the optic for night vision use. While you can sorta get away with using most optics with night vision by using a dim setting, that can damage nightvision over time. NV setting reduce the brightness enough so that you will not damage your expensive night vision device.
I did some shooting with this Eotech and with a Aimpoint T-1 on the same rifle. Shooting from the bench, or rapidly engaging multi targets off hand was quick and easy with either optic. Both were fast and easy to use, but I would not say the Eotech was any faster or easier than the Aimpoint. The only real noticeable difference in use was that this Eotech 553 felt much heavier on the rifle than the T-1. Looking at the stats on them, the Eotech is about 3 times heavier. That is an additional half pound on the rifle over the weight of the T-1.
I used to be a major fan of Eotechs. But over the years I saw multiple Eotech Holographic Weapon Sights fail in various ways. Battery terminals would break, I’ve seen the prism break loose. Lenses delaminate, and reticles dimming. The biggest issue was that many Eotechs would drain their batteries even when off. I found that my Eotech 512 would drain the batteries even when off. I had to store it with the batteries removed. I felt the high failure rate of Eotech sights was damning on its own.
Turns out it gets worse. L3 was aware of issues with their like of Eotech sights, and were covering it up. L3 paid a settlement of 25.6 million dollars over this. The biggest issues they were covering up were that the sight wasn’t actually parallax free and that there could be massive zero changes if the optic was exposed to temperature changes and it turns out that Eotech sights also were not as waterproof as they are suppose to be.
Despite these persistent issues, you still see fans of Eotech sights defend them online. The most often statement in Eotech’s defense is that the Navy SEALs are using Eotech sights. I point out that the SEALs use what they are issued, are the individuals are not purchasing these out of pocket. They also have far more range time and funding so doing stuff like rezeroing before a mission or replacing batteries each mission is a non issue. But even NSWC Crane had to issue a Safety of Use Message about the Eotech warning about a 4 MOA Thermal Drift problem, fading and disappearing reticles, and 4-6 MOA parallax error. SOCOM acknowledge these sights have issues.
So if you want a known substandard sight, buy Eotech.
“It is probably the perfect optic for the AR, isn’t it.” -Shawn.
I stumbled across an old email from 2013 where I told a friend that I thought the T-1 was the king of reflex optics. Despite there being the newer T-2 and similar optics like the Trijicon MRO, I still stick to my statement.
What makes the Aimpoint Micro T-1 great is very small size, light weight (3 oz with out mount) and long battery life of up to 5 years. That makes a combination that is hard to beat.
There isn’t much not to like about the T-1. Now if you wanted to start a list of complaints the first would be cost. After that is that the stock mount is low profile so you would need to either add a riser or use an aftermarket mount if you are attaching it to an AR15. I prefer the Larue QD mounts for the T-1 but that does add to the price of the optic.
When people talk about the massive battery life of modern optics like the Aimpoints, they are referencing the possible battery life at about three quarters maximum brightness (a normal operating brightness). When the T-1 is set to maximum brightness, this battery life is shortened to about 10 months. But to put it in perspective, the Trijicon MRO also has a battery life of 5 years on setting 5 of 8, but only 25 days on the brightest setting. Many older optics and cheap optics will only run for a few days.
The T-1 is available in 2 and 4 MOA models.
I have a hard time getting the reticle to show up well when I snap photos of them.
Here is a picture of a 2 MOA T-1 with the brightness on max so the dot would show up in the picture. This one has an IO/Tango Down cover installed, and a KAC battery cover.
This is a 4 MOA T-1 on a Larue LT660 mount. The dots show up clearly and bright in person, I don’t know how to get them to show up in pictures well.
Adjustments are 1/2 MOA. Adjustments require a tool, which is provided as the cap for each adjustment. Be careful as it would be easy to lose the adjustment caps.
Flipping the cap upside down allows you to use it as the adjustment tool. It shows you which direction you need to turn for the adjustment.
Now I would say that the only real downside to the T-1 is cost. But if you run it co-witnessed with fixed iron sights, the small window makes it a little harder to use. You might want to consider a larger optic if you are running it with fixed iron sights.
It is normally recommended to go with the 2 MOA models. You can turn up the brightness if you want a larger visible dot, and it is suppose to look better if you are using a magnifier. I have a mix of 2 MOA and older 4 MOA models, and much to my surprise when I was using them size by with with a magnifier the 4 MOA dot was crisper under magnification.
For a long time I said I never saw an Aimpoint fail, but more recently I have. Both cases were user error. The first was an used T-1 I purchased where the previous owner cross threaded on an aftermarket KAC battery cap. When they attempted to remove it they put a wrench on the stuck cap and turned the brightness adjuster past its stops. I sent the optic back to Aimpoint and while it took a while, they repaired it and sent it back at no cost. The second case was my fault, and a really simply error. I have a KAC battery cover, and this cover has a space so you can put a second spare battery in it. I didn’t have the second battery under this cap, so then under recoil the battery would pop out of place and my sight shut down. Installing a second battery (as per the aftermarket cap requires) solved this issue.
I love how small and light the T-1 is. When used you can sort of see around it when you keep both eyes open and it takes up much less space in the view than most other reflex sights. I’ve bought all of mine used, as they are hard to screw up and and you can save a good bit of money getting it used. The Micro T-1 is easy to use and I highly recommend it.