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Last updated September 20, 2020
Most firearms can be used underwater for at least one firing. Automatics may not properly eject the case, while revolvers can shoot multiple rounds. Bullets may penetrate 4-5 inches into ballistics gelatin when fired at a range under three feet. The more powerful the round, the more ineffective it is in water. The waters' drag on the larger bullet is greater than the extra force from the additional powder of the larger cartridge.
If air is trapped inside the firearm, it may explode if the bullet passes from water to air to water. Shotgun receivers have a tendency to rupture when shot underwater. Keep in mind, this is a generalization and there still may be a shotgun out there that may work.
There are two false arguments for the three-round burst control: (1) it is more accurate and (2) it conserves ammunition. The first shot of a three round burst is just as accurate as a single shot on semiautomatic. Subsequent rounds could be more or less accurate depending on variables such as the target's movement and the environment. As for the second argument, shooting on semi-automatic conserves even more ammunition by the same argument that shooting on three-round burst as opposed to shooting on automatic conserves ammunition. In reality, there is no data that supports this assumption.
During the Army's experiments with burst size, various holding positions, etc, the Army concluded in the Analysis of M16A2 Rifle Characteristics and Recommended Improvements (1986) that three-round bursts may not be the optimum burst size. In the majority of bipod-supported automatic fire holding positions, firing up to five and ten round bursts, the third round will many times find the limit of the group size, with subsequent rounds moving back in toward and around the initial aiming point. An increase in the number of rounds in a burst may increase the probability of a hit on a stationary target, but would decrease chances of a hit on moving targets. Therefore, a three round burst is ideal unless heavy covering fire is required.
Ever see the following three references in the M4/M16 Unit and Direct Support Maintenance Manual (TM 9-1005-319-23&P)?
We have never even seen these pubs in the hands of our units' armorers. We didn't even know what TI stood for! So we went on a hunt and it turns out that the TI's are USMC Technical Inspections. Since the last M4/M16 23&P was a "joint service" manual, they put in all the references from all the services that will be issued the manual. So if you are in a different branch of service and find that you don't have access to these pubs, don't be surprised. The newest draft of the operator's manual is not being distributed to the USMC and does not include the TI's in its references. The new M4/M16 Operator's Manual came out early December 2008.
The Marines over at the Parris Island Drill Instructor school say the TIs were never was published. They tried to obtain them for their library shortly after the USMC said there was such a pub, but they have never been able to obtain the TIs. With that being said; our official opinion is "They do not and have never existed."
These TIs are inspections that are routinely performed by the unit supported maintenance (DS/GS support units). In the past, active duty units were required to have the weapons gauged annually for field service. The requirements for other than active duty units (i.e. National Guard, Reserve) was gauging once every 2 years, or bi-annual. Unless the units training or firing qualifications have changed and require more frequent serviceability inspections. Also the units being activated for overseas deployments will have to pass this gauging prior to deployment. That is mandatory for all units. A list of special tools required by the support maintenance are listed in the last two pages of the Appendix B-3 of the 23&P. NOTE: These items are a Direct Support function to have on hand. Not a unit's responsibility.
You might feel cozier wearing just your birthday suit, but you won't be any warmer. Both down and synthetic bags work by trapping your body heat. The thicker or loftier a bag's insulation, the better it is at retaining warmth. Wearing a thin layer of clothing adds one more tier of insulation to make you even toastier. Of course if you wear too much clothing, like a down mountaineering suit, you could compress the bag's insulation and actually reduce its effectiveness. Another reason to sleep in base layers: It extends your bag's lifespan. That's because oils from your sweaty skin can penetrate your bag's inner lining to soil and damage the insulation. A clean bag is a warmer bag, so save the skinny-dipping for the lake.
The Accuwedge reduces rattling, and supposedly improves accuracy and prevents wear. It is a small piece of rubber that fits below the take down pin in all M-16 / AR-15 clones. The wiggle between the upper and lower is due to forging and machining tolerances, which guarantees interchangeability. The Accuwedge only reduced wear and has no effect on accuracy.
Formal testing conducted at Rodman Laboratories in the 1970s verified that accuracy was not affected by normal receiver tolerances. The fact is that the bullet exits the bore before movement of the receivers produces a measurable effect. It does make a shooter feel more confident about their rifle. While confidence is a positive effect, it should not be based on incorrect reasoning.
If the upper & lower receivers rattle every time the recoil energy is transferred. It is not unreasonable to assume that the upper and lower receiver take down pin holes are getting worn down from moving around against the take down pin. The pin is steel and the receivers are aluminum. Guess who loses the battle over time.
For DIYers, reduce movement by inserting materials such as paper, rubber, or epoxy somewhere between the receivers to create a tight fit. If you prefer a more professional look, get an Accuwedge here.
For additional information, please read ArmaLite's technical note on receiver tightness:
Oh no... not another product using titanium for marketing hype. Recently, titanium has been used as a marketing catchphrase for products ranging from laptops, cell phones, mechanical pencils, and even shaving razors. If you are willing to pay twice the cost of a steel firing pin for one made of titanium, you too can join the mindless consumer masses. For comparison, these are the weights of several common firing pins:
The already light weight steel pin travels such a short distance that the difference in inertia between the steel and titanium parts just doesnt make an appreciable difference. Despite high tensile strength, titanium has poor impact resistance; its relatively inflexible. Repeated stresses eventually cause structural breakdown.
G. David Tubb, who is largely credited with the development of titanium firing pins for bolt action rifles (his SpeedLock Systems), uses steel tip inserts in his products for this very reason. His pins work well, but he doesn't manufacture AR15 firing pins due to the aforementioned reasons.
For additional information, please read ArmaLite's technical note on titanium firing pins:
Here are DGI's numbers to backup ArmaLite's technical note:
While in Iraq, our chain of command (COC) required us to keep our dust-caps off our weapons to always be combat ready. The M16 operator's manual (Army TM 9-1005-319-10), say the contrary. The Ch.9 p.1 states, "Removal of the muzzle cap prior to firing is recommended. Place it in your pocket for future use. However, it is not dangerous to fire the weapon with the muzzle cap installed." Okay, so my COC is a little right... it's not recommended, but it's not dangerous. But! That doesn't mean we should start listening to our COCs, right? Ch.9 p.6 states, "The use of overall weapon protection cover, muzzle cap, and spare magazine protective bags will help protect the weapon ammo from sand and dust. Use these items when the tactical situation permits." Maybe the tactical situation did not permit a weapon protective cover, but the muzzle cap can be fired with the muzzle cap installed. The DEA's Colt M16 manual says that "a cap is designed so that a bullet will pass through the end without affecting accuracy and without causing a safety hazard to the user." So there's no reason not to use one. In fact, both manuals recommend it. I believe a big, "HaHa! I told you so" is in order.
This plentiful substance is composed of about 95% water and 5% uric acid, salt, and some other compounds. Not too scary yet, but as the urine travels through the urethra, it collects bacteria so wed like to dispel some myths regarding the many handy uses of urine.
You may commonly hear people say "over and out" and "loud and clear." Contrary to popular belief, you should not use the phrases "over and out" and "loud and clear." According to the Army's definition of proper radio protocol, certain prowords can not be used together.
"Over and out" is a contradiction of terms. The proword "over" means this is the end of my transmission to you and a response is necessary. The proword "out" means this is the end of my transmission to you and no answer is required or expected.
"Loud and clear" is probably one of the most misused responses to a radio check. When responding to a radio check, you need to report the signal strength and readability. Appropriate prowords for reporting signal strength are: loud, good, weak, very weak, or fading. Appropriate prowords for reporting readability are: clear, readable, unreadable, distrorted, with interference, or intermittent. If the signal strength and readability are loud and clear, you can respond with "roger." Meaning I have received your transmission satisfactorily. The goal is to reduce transmission time as much as possible. Do not use loud and clear together.
Through basic training you may have heard that you should not carry the M16 by its carry handle. Such phrases as, "This is not your luggage" should come to mind. Tactical discipline may well require prohibiting soldiers from carrying the rifle by that handle in a dangerous area, but in a ready position of some sort instead. That in no way reduces the utility of the handle on other situations. Despite what is taught during training, the carry handle was named that for a reason.
According to Armalite representatives (the original makers of the M16/AR15), "The (carry) handle also served to protect the charging handle in the top of the receiver of early AR-10s and 15s. The top mounted charging handle was dropped but the handle was kept." This explains why new versions of this rifle can be made with a flat top (Picatinny rail system) instead, altogether eliminating the carry handle issue.
The rumor is that removing the heel cup from your combat/jungle boots will make them more comfortable and you'll get fewer blisters. The heel cup can be felt from the outside of the boot and is the stiff area that runs around the back and bottom edge of the heel.
We removed the heel cup from the a pair of jungle boots, and used them extensively. We noticed zero change in comfort. They were neither more comfortable nor more uncomfortable. Even if removal initially seem more comfortable, you run the chance of developing bursitis of the heel, which is extremely painful and permanent. You should never remove the shank, which is a metal or plastic arch support under the insole, as doing so will definitely cause some major foot problems. Still... for those of you who are overly-curious and cannot be convinced otherwise, we have included instructions to prevent you from ruining your boots altogether.
Basic boot information: The portion of the heel cup that wraps around the bottom is glued and tacked in place. The tacks stick up with the pointed end pointing toward your foot. The tacks also help secure the leather inner sole. The tacks start in the sole of the boot. Therefore, you must pull the heel cup free from the glue and tacks.
The Removal Process: From the outside of the boot, carefully cut and remove the stitching that runs around the heel (for combat boots, also cut up the back of the boot and stop cutting about an inch from the top). Do not cut along the base of the heel! Once the stitching is removed, peel the strip of loose leather down toward the sole of the boot. This should expose the heel cup. Next, pull the front part of the boot and shaft away from the heel. This should separate the insole from the tacks. You can then begin working the heel cup loose with a good knife and some pliers. Once one edge of the heel cup is separated from the glue and tacks, the rest should come out easily. After removal, pull the heel leather back up and take your boots to a professional shoe repairer to have them stitch the leather back together. This should cost around $15 for both boots.
Again, this is not recommended and may cause long-term foot injury.
Springs do not lose strength over time if left in a compressed state. With extreme temperature and humidity aside, springs will "lose strength" when deformed beyond their elastic limit, or through cyclic wear.
Ohh but Delta Gear, isn't compression duration a factor in creep? Creep is so negligible in stainless steel and Cr-Si steel that both are prone to fatigue before they fail from creep. So cyclic wear is the dominant mechanism for fatigue in magazine springs.
How long would creep take to cause a fully loaded spring to fail? According to the ASM manual referenced below, 316 stainless steel at high temperature (~550°C) under a reasonably medium-high constant stress (160MPa) will cause a 1% plastic deformation (1% is a commonly used failure criteria) after 11.4 years (actually 100,000 hours). The Arrhenius equation shows us that the creep rate increases as temperature increases. If you solve the Arrhenius equation for change in time, integrate, and take a ratio of the equations, you can see that at room temperature you can expect the characteristic time for creep to increase by a factor of about 10^61. So, unless you plan on leaving your magazine loaded for longer than the lifetime of the universe, creep is not an issue at room temperature.
Is it possible to compress a compression spring to the point of deformation? In very extreme, abnormal circumstances... yes. But magazine springs are designed to be fully compressed under a normal load without exceeding the elastic limit.
In conclusion, there are three modes of spring failure: deformation, fatigue, and creep. Deformation can be avoided by not stretching or compressing the spring beyond its elastic limit. Fatigue can be avoided by not using the spring. And creep is inconsequential. Therefore, if your life will depend on the proper functioning of your magazine, keep new, fully loaded, magazines set aside for that special day.
ASM Specialty Handbook: Heat Resistant Materials. Ed. Joseph R. Davis. Materials Park, OH: ASM International, 1999. 123-126. Print.
Fiction can be fun. Have you heard the myth: "If you have malfunctions such as double feeds, try leaving two rounds out of your magazine to reduce the spring's compression." The truth is downloading mags was originally done to prevent old followers from jamming, depending on manufacturer and model. Old followers didn't have legs to prevent them from rocking when fully loaded. New followers have legs to prevent rocking and don't have this problem, so fully-load your heart out. Obviously the magazine should work as its designers intended.
As for the spring compression theory... The restoring force from a spring with a proportionality constant "k" displaced a distance "x" from its equilibrium point is given by Hooke's Law (F = ma = -kx). So the force that rounds are pushed into the chamber increases linearly as you increase the number of rounds. So leaving two rounds out would lessen the compressive force of the spring. But if companies like the Sterling company in England can make a very reliable 40 round AR magazine, then why would it be a problem with 30 round mags that use smaller springs. Obviously the difference in the spring's compressive force with two rounds left in is not significant enough to cause a malfunction. So force is not the issue. Let us examine another problem, fatigue.
The myth may have had some credibility 50 years ago, but not any more. The original concern was that if you fully loaded a magazine and stored it for long periods of time the spring would set (work harden) and then weaken when used. This was caused by fatigue. If the torsion stress and bending stress in the spring was greater than its yield stress, it would fatigue and you could soon have failures. If you design the spring properly, it will not fatigue. That is if the wire dimensions were large enough and the spring could not be over compressed, the yield stress would never be exceeded. Magazine designers know this and properly construct their springs.
Also an incorrectly designed spring would exceed the fatigue stress of the spring metal each time it was fully loaded and you would get a fatigued spring after using the mag several times. Either way, this is no longer a concern. Most magazines don't fail due to spring problems. You're more likely going to experience mag trouble due to bad followers or bent feed lips.
The bottom line is that the downloading mag myth is bullshit, and in a firefight those two rounds could cost you your life. It is equally important to do a proper PMCS of your magazine as it is the rifle. If your weapon continuously jams when you fully load your magazine, carefully inspect the weapon and magazine to standard. Make sure you haven't jammed 31 rounds in a 30 round magazine (dont laugh, it happens!). Doing so makes it difficult to chamber that first round.
Supposedly listed in the Ranger Handbook of Field Expedient Devices (which we can't find anywhere in existence) in the movie Saving Private Ryan. The Sticky Bomb is alternately referred to as a sticky charge or sticky grenade. The makeshift explosive was supposedly employed by paratroopers during the Battle of Ramelle consisted of grease-covered socks filled with composition B or TNT explosive material. A fuse was inserted into the explosives and lit just before the explosive was placed on its target. Since we couldn't find the Ranger Handbook of Field Expedient Devices, we looked for the "Sticky Bomb" in the following military manuals:
We could not find the "Sticky Bomb" or any of its aliases in any relevant United States military manual. We couldn't even find any explosives that were "sticky". The closest improvised explosive that we could find would be a satchel charge. During WWII, naval demolition teams used explosive filled socks, which made it easy to quickly tie the explosive around a pole, large weapon barrel, or onto a gate. The "Sticky Bomb" was produced by the British during WWII, but there were no greasy socks involved. They British experimented with it but found it too hazardous for use. The Germans and some of their enemies had manufactured anti-tank charges that attached to the armor using magnets, while the US relied on improvised techniques. In 1943, the German chemical company Zimmer developed anti-magnetic paste called "Zimmerit paste" to prevent the allies trying the same thing, though there was never an allied magnetic charge. It was a combination of these materials:
This would create a paste that, when spread over an ironeous surface, would make mines unable to stick to the surface. The paste itself does not contain any anti-magnetic abilities, unlike what is often believed (this error is from an Allied intelligence report from 1945). The paste just makes the surface difficult to adhere to. After saying all this, it still remains that "Sticky bombs" are not a proven technique.
Are your BDU bottoms more faded than your blouse (or vise versa)? Some Soldiers recommend that you wear your BDUs into a swimming pool to make them match better. The bullshit alarms should sound. Chances are that this will cause the blouse and pants to fade the same amount.
Another rumor is that TC 21-21 Water Survival Training states something to the effect of "BDUs + Chlorine = unsafe toxic pool." This is nonsense according to TC 21-21 (June1991) which says nothing of the sort.
If the blouse and pants are slightly mismatched, just wash the slightly darker piece in your washing machine with a small capful of bleach. The best solution is to buy new uniforms as a complete set and keep the blouse together. Mark the tag with a number/letter code using a laundry marking pen to make it easier to keep them paired together.
As your ruck gets worn out, the paint on the frame will begin to come off. The myth is that you can strip the powder coating off your ALICE Pack Frame and Type III Hard Anodize your frame (the hardest finish you can put on aluminum). The problem is that all of the rivets are made of steel along with the kidney pad buckles. It is possible to anodize your frame by following these instructions, but is it really worth your time and money? We at Delta Gear think the ALICE pack sucks to begin with so why do all this work to make a shitty ruck a little better than shitty? This will cost you over $35 and it takes a days worth of work. If you're still not discouraged, here it is.
Before stripping, drill out the 27 rivets with a 7/32" drill bit. Remove the plastic plugs that are in the ends of the tubing. Replace the 27 steel rivets with Aluminum Threaded Posts and Screws. This solves two problems. When you start carrying loads in the 50-80 pound range, the rivets in the ruck frame may come loose or break, specifically the rivet that goes through the vertical support member. If this happens you're screwed for the time being.
Get a small can of aircraft stripper from your local autoparts store. Tape down some foil on the ground or use a disposable oven drip sheet. Make sure you put on your goggles, nose/mouth mask, and chemical resistant stripper gloves. This stripper will burn your skin and can really damage your eyes. Apply a generous coat with a chemical resistant brush and let it sit for 45 minutes. Rinse the frame clean with your garden hose (recommend using a nozzle for better pressure). Repeat the stripping process if necessary. Let it dry or wipe it dry. Remove any leftover paint with very fine steel wool and a dental pick. Don't use a wire brush, as this can damage the finish of the aluminum.
Insert a " Aluminum Threaded Posts and Screws into any hole that goes through the tubing. Insert - "Aluminum Threaded Posts and Screws into each hole that doesn't go through the tube. Use either a lock ring washer, wave washer, or rubber washer to keep the threaded posts from coming undone and to keep them from slipping while tightening. Don't over tighten the Threaded Posts as the frame may warp, or the aluminum threads might strip.
Find some aluminum rod that you can bend into the same shape as the steel kidney pad buckles. Finish reassembling everything. Now send it all to the local anodizer to be Type III Hard Anodized and your done!