Tag Archive for m4
In the world of firearms people usually fall into one of two categories, AR15 fans and AK47 fans and while this won’t be an article comparing the two, knowing the differences gives us a better understanding into why toughening up an AR rifle might be a good choice for you.
In many people’s eyes, the AR15 style rifles are a little lacking in the durability department for hard duty use and training. The reasons for this are mostly due to the gas operating system and certain areas of the design.
Now I personally don’t look down on the AR the way some do (although I do love my AK) but if your looking for a way to add a little durability to your AR then here are a few tips.
1) First lets start with the barrel. Now this is one of the two areas of an AR style rifle that are the most important parts of the gun and need to be good quality. So to toughen it up the best option is to go with a chrome lined, cold hammer forged barrel either in a government or heavy barrel profile. This will make extraction easier, even with the dirtiest of ammo and will increase the life/round count of your barrel. Buy from companies with a good reputation for quality CHF & chrome lined barrels.
2) Next we look to the bolt carrier group. One sure way to toughen it up is to go with a chromed plated or nickel boron coated BCG. This will give you much greater shooting time before having to break down and clean your rifle. There are several companies making chrome and nickel boron coated BCG’s and most are of good quality.
3) Next we look at the trigger pins. These hold your hammer and trigger in place and can on occasion back out and cause malfunctions. The easy solution for this is to pick up a set of Anti Walk Pins, you can pick them up just about anywhere and they’re easy to install and they prevent the pins from backing out of the lower receiver.
4) Finally we look at the gas system. This is the biggest complaint from AK fans in that the gas system fouls up the action by blowing hot gas and carbon back into the receiver. The easiest way to fix this is to go with a piston system for your AR. It eliminates this particular issue but do make sure the piston kit you install is a quality kit.
So there you have it, if you want to bring the durability level up on your AR style rifle, there are four ways to toughen it up.
The “Mil-Spec” or industry standard for BCG’s are as follows …… Carpenter 158 steel, shot peened, gas key secured with grade 8 fasteners, chrome lined and parkerized. While there are some variations and options like different coatings, these standards will be the same for most BCG’s on the market.
One of the first things you want to look for in a BCG is that it’s been MPI and HPT tested. MPI stands for “magnetic partical inspected” and HPT stands for “high pressure tested” …… basically these are tests to help determine if there are any issues with the BCG such as cracks or hairline fractures that could cause failures. These tests are also use on barrels as well.
Now many companies test their BCG’s in these ways but some companies “Batch” test their BCG’s which basically means that for every batch of BCG’s they produce, they only test one BCG. Definitely something you’ll want to check into when purchasing. Companies like BCM, Daniel Defense, Spike’s Tactical & Palmetto State Armory are examples of companies who individually test their parts.
Next you’ll want to check the staking of the gas key on your BCG. Now this can be pretty hard to do if your buying online so do your research on the different companies to find out who has a good reputation in this department.
For those that don’t know what the staking of the gas key is, I’ll explain. The gas key is the part of the BCG that comes into contact with the gas tube coming from the gas block on the barrel and it is what the gas blowing back from the barrel comes into to contact with to cycle the action of the bolt. Because of all the pressures associated with this and because the gas key is attached to the rest of the BCG by two small hex bolts, it’s inportant that those bolts are properly “staked” into place to prevent them from backing out or loosening due to the pressure and causing a failure.
The next thing you’ll want to take into consideration is wether or not your getting an AR15 style BCG or an M16 BCG. The differences are noticable at the rear of the BCG where the top and bottom of the M16 style BCG are the same length adding weight and stability to the action and also slightly slowing down the cycle rate which of course is preferable for full auto rifles. The AR15 style BCG has the bottom rear of the BCG cut back to reduce weight and cost of the BCG.
Now while most civilian shooters won’t notice the difference between these two types of bolts, now days the two kinds of bolts are so comparable in price that you might as well just go for an M16 style BCG.
One final thing to keep in mind is the chrome lining. Some companies advertise chrome lining on their BCG’s and some don’t, but keep in mind that chrome lining in the body of the BCG where the bolt rides and inside the gas key is an industry standard. So while you may not see it advertised, I’m not aware of any company currently manufacturing a BCG without chrome lining.
So thats its, those are the basics. There are some customized options out ther like specialty o-rings and ejector springs that you’ll sometimes find on some BCG’s but for the most part those are upgrades or customizations and aren’t a part of your standard BCG.
There seems to be quite a debate going on recently about what is a better gas system for the AR platform. So we’re going to take a look at a few of the basics concerning these two very different gas systems and compare the two and hopefully help you, the end user, decide what will work best in your rifle.
First off we have to acknowladge that the AR platform was designed to work with the Direct Impingement gas system and that for the most part Piston Systems are basically just add-ons or adaptations of the original DI designed rifle. It’s basically a modification to turn a rifle designed to work properly with DI into a piston rifle.
Some area where the DI system outshines a Piston system are as follows ……..
Free Float barrels – This is an obvious one, basically even though you can technically free float a piston rifle, it makes little sense as your negating the purpose of free floating a barrel by adding a moving piston that connects the barrel to the receiver.
Less Moving Parts – Again, pretty obvious, but it’s worth mentioning. Less moving parts equals less parts to have issues with.
Lighter weight – Self explanitory, although a few ounces shouldn’t make or break your purchasing decision.
More Common – This equates to easier to find and cheaper to purchase parts, along with more compatability with other rifles that might be used for parts interchangability.
Accuracy – This is another area where it should be obvious that by having a moving piston adding recoil, right above your barrel, your going to loose accuracy, especially for follow up shots.
Cost – Obviously because of its commonality and because its usually the way a rifle is manufactured, the cost is significanty less than that of a piston system.
Industry Standard – This comes into play because at this time there really is no industry standard for piston systems like there are for DI system rifles. There are many good companies that manufacture high quality piston kits or rifles designed to function with a piston system, but those companies do not all manufacture their kits and parts to be interchangable as every other part on an AR platform rifle is.
Now lets look at a few areas where the Piston System does a particularily good job ……..
Cleaner running & Heat Resistance – This is the biggest and most obvious advantage over a DI system on an AR platform rifle. The biggest downside to the DI system is that it dumps hot gas and fouling into the action of the rifle and the piston system takes care of this problem by venting all the gas elsewhere making the rifle easier to clean and require less maintenance and cleaning.
Reliability – Because of the issues with the DI system fouling up the action a case can be made that a Piston system is inherently more reliable than a DI system because fouling and carbon build up do not enter the action and potentially cause reliability problems.
Suppressors – One reason suppresors tend to work better with Piston systems is because the nature of a suppressor restricts gas coming out of the muzzle and with a DI system all that restricted gas that would normally be blown out of the muzzle gets directed back into the action and not only causes even more fouling than normal but has also been known to cause excessive gas to come out to areas of the receiver like the charging handle area and blow gas into the face of the user. For this reason a Piston system, which drastically cuts down the amount of gas that is distributed into the chamber, is perfered for rifle fitted with suppressors.
SBR – Piston systems also tend to function very well on Short Barreled Rifles because of the higher port pressure, making Piston systems popular on barrel lengths shorter than 16″.
Running Dry – The piston system is much more capable of running on a dry chamber and action as opposed to a DI system that requires much more lubrication to continue to operate efficiently due to a high rate of carbon build up and fouling distributed into the action of the rifle.
So those are the pro’s and con’s of Direct Impingement vs Piston Systems on AR platform rifles.
In the end, for most civilian shooters, the differences are negligable and either system will work very well for just about anything you will ever use your rifle for. It really comes down to personal choice.
First let go over the different types of barrel steel and processes used to make the barrel. These will be CMV, Stainless & CHF
Chrome – Moly – Vandium (CMV)
This is the most common type of barrel steel used. It comes in mainly two forms.
4140 – carbon spec. 0.43 – Some say this mat be more thermally stable?
4150 – carbon spec. 0.48 – Some say this may be better for full auto?
Most shooters (even heavy shooters) will never notice a difference between 4140 & 4150 CMV barrels
The US military uses 4150 CMV
Stainles barrels are heavier
They can also be more accurate because the alloy is more maliable and allows for finer precision during the manufacturing process, if manufacturer takes time to do so.
Buy from a respected manufacturer to ensure barrel was precisely made for better accuracy
Cold Hammer Forged (CHF)
Cheaper cost per unit for manufacturer but manufacturing equipment is much more expensive making it harder to profit unless many units are produced and sold, which is why so few companies produce CHF barrels compared to those companies that produce CMV barrels.
CHF barrels are usually chromed lined.
Unlike standard barrel manufacturing, where a barrel blank is placed on a lathe and a machine drills the rifling into the barrel blank, with CHF a barrel blank is placed in a CHF machine and a mandrel with reverse rifling on it is placed in the barrel blank and the machine presses the steel onto the mandrel to press the rifling into the steel.
This process has the potential to make for a more durable and longer lasting barrel if done correctly, otherwise it offers no more barrel longevity than standard manufacturing processes.
Buy from respected manufacturer to get the benefit of a more durable barrel. FN is the manufacturer of choice for many shooters as they manufacture this same barrel for the US military.
Chrome Lined vs Non-Chrome Lined
Chrome lined barrels tend to be better at extraction and corrosion resistance and cleaning but tend to be slightly less accurate than standard non-chrome lined barrels, but this difference is so nominal that most users will never notice a difference.
If there is a difference it is probably more likely due to poor manufacturing than the chrome lining.
If you’ll be shooting steel cased or dirty ammo often chrome lining might be a better option for you, otherwise it really makes no difference and chrome lining is more expensive (by about $50 to $75 for a barrel), so if you don’t plan on shooting that type of ammo don’t waste the extra money.
Barrel Twist Rate
The barrel twist rate basically means how many complete revolutions does the rifling make inside the barrel.
For example a 1:7 twist rate means that every 7 inches the rifling makes one complete revolution around the inside of the barrel. So the smaller the second number, the faster the rifling spins the bullet.
The most popular are 1:7 and 1:9 (although a newer 1:8 twist rate is becoming more popular).
Basically the twist rate breaks down like this – the heavier/longer the bullet is the more spin is needed to stabalize that bullet, so for instance a 62gr 5.56 would have much better accuracy and range out of a 1:7 twist barrel than a 1:9.
The best overall twist rate will be 1:7 because it’s accurate with the widest range of bullet weights and lengths (although some people claim that a 55gr bullet can be overstablized in a 1:7 twist barrel and loose some accuracy, the percieved accuracy loss is still negligable and most shooters wouldn’t notice a difference)
All in all 1:7 is going to be your best bet although it can be slightly more expensive, it is fast becoming the industry standard. However if all u plan on shooting is 55gr loads then you might be better served just getting a 1:9 twist and saving a little money.
Chambering is pretty simple, make sure your barrel is chambered for 5.56mm ammo.
This allows you to fire either 5.56x45mm ammo or the cheaper .223 ammo.
If you purchase a .223 barrel you should not fire 5.56 ammo out of it.
Most AR barrels are 5.56 but there are still a few manufacturers out there making .223 only rifles, so be aware.
There are many options for barrel lengths, 8.5″ – 10.25″ – 11.5″ – 14.5″ – 16″ – 18″ – 20″ and a several others.
We’ll only be discussing the most popular lengths 14.5″ – 16″ – 20″
16″ is the most popular as is suites most types of shooting including long range, CQB, defensive shooting & just having fun at the range.
14.5″ is basically the same in function and purpose as the 16″ except due to laws a 1.5″ muzzle device must be permanantly attached to the barrel to ensure the length is at least the 16″ legal limit
20″ is usually religated to longer range shooting and range use and generally considered to be less desirable for CQB or defensive situations where a shorter barrel would be more useful.
Your standard barrel contours are Lightweight (pencil) Barrel – M4 Contour (government profile) Barrel – Heavy Barrel – and many other barrel designs, many of which are custom or fluted designs that each offer their own unique advantage and disadvantages. We’ll discuss the most popular.
Lightweight (pencil) barrel is very popular for a lighweight easily manuverable rifle design. If your doing a lightweight build this might work for you, but keep in mind that it does have a shorter life than other barrels and should not be choosen if your a heavy shooter who puts alot of rounds through your rifle.
M4 contour (government profile) is pretty much the standard in most carbine length rifles. It offers good weight with good barrel life. Great for most shooters.
Heavy Barrel is a considerably (in barrel terms) thicker barrel adding life and heat resistance to your barrel but it does so in exchange for more weight.
So thats it, the basics of AR15 barrels. Hopefully this article will hep you in choosing a barrel for your next AR purchase or build.
Buying an AR can be a daunting task, especially if its your first time. Deciding what to buy and how much to spend can be an endless chore. If your like me and don’t feel like spending $1000 on a stock rifle only to then spend another $300 to $400 in accessories to get the custom look you want then I might have a few tips for you on how to get a quality rifle for an affordable price.
1) Make the decision to build the rifle yourself – It may seem like a daunting task but it really isn’t dificult at all, anyone with even a basic knowlage tools and a little common sense can put one together very easily with a little help from any number of tutorial videos available on youtube and elswhere.
2) Buy a stripped lower – This is very easily done, it’s the only part of the rifle considered a firearm because it has the serial number on it, so it’ll have to be bought from an FFL or ordered online then shipped to your local FFL. The cost one these start at around $50 to $60 and you shouldn’t need to spend much more than that to get one. In the end you’ll drop about $100 for the lower, shipping and FFL transfer costs.
3) Buy a rifle kit – Many companies sell these kits, it usually consists of a completely assembled upper (upper receiver, barrel, front sight, handguards, colt carrier group and charging handle all assembled), a lower parts kit to install in your stripped lower, a pistol grip and stock. These kits can be had for about $450 give or take from companies like Del-Ton, Blackthorne & Palmetto State Armory.
4) Start adding accessories – Heres a list of a few accessories that will give your rifle that custom $1200 look.
Magpul Rear MBUS Flip-up sight – $49.99
Magpul B.A.D. Laever – $22.95
Magpul Polymer MOE Trigger Guard – $8.95
Magpul XTM Rail Covers (3 sets) – $21.00 ($7.00 each)
UTG Quad-Rail carbine length – $29.99
Blackhawk Ergo Grip – $19.99
Pro-mag Vertical Grip – $8.99
YHM Phantom Flash Supressor – $24.95
Spike’s Tactical Nickel Boron Battle Trigger – $59.95
Spike’s Tactical Complete Bolt Carrier Group – $109.95
Polished Charging handle – Free (DIY project)
Total for upgrades – $356.71
So once you’ve done all that you’ll end up with a quality custom look rilfe for under $900, and if you just want a stock rifle you can leave off the accessories and have a rifle for under $600 that will do you better than most other out of the box rifles that cost upwards of $800.
The first thing to remember when buying an AR …… most of the parts being used, no matter what the name your buying, either came from the same place or were made using the same equipment and made to the same specifications if your buying a “milspec” rifle.
Now if your going for a higher end rifle that has stricter tolerences and is built to a higher standard for more accuracy (although those companies sell milspec rifles as well) then thats a different story.
The next thing we need to understand is, what is “milspec” for an AR rifle. First off, there are only 2 companies that know what true milspec is or create true milspec rifles and those companies are FN & Colt because these are the only 2 companies that have government contracts and create true milspec rifles.
Most of what we in the civilian market call “milspec” is really just an industry standard chosen to get as close to true milspec as possible without the government inspection process. These industry standards include things like …..
5.56mm chamber (shoots 5.56 or .223)
11595E Barrel Steel
Manganese Phosphate finish barrel
F-marked front sight
Standard threaded 1/2 x 28 tpi barrel for muzzle device
Forged A2 front sight base w/ bayonet lug
Barrel is machined from chrome-moly, high vanadium steel and hardened to a U.S. government Mil-spec of Rc 26-32
The barrel, and all external steel parts, are manganese phosphate finished IAW 22.214.171.124 of Mil-STD-171, the U. S. government’s recommended protective finish for steel
Barrels are .950 diameter under the handguards .750 under the front sight base (standard M4 contour barrel)
Forged A3 upper reciever made from certified forgings, hardcoat anodized IAW Mil Spec A8625, Type III, Class II, black per No. 37038, Table IX with nickel acetate seal, as per the Mil-spec
Buttstock tube is the mil spec thickness 1.145″ OD
M4 style feed ramps
So those are some of the “Milspec” specifications that most manufacturers are adhering to, but they are basically just industry standards, but for our purposes we’ll just use the term “milspec” as the closest you can get to a true milspec rifle is something from Colt and it still won’t be true milspec.
So if u are just getting something milspec, its all the same as far as parts quality. You may have some differences like types of finishes or chrome lined barrel or not, or a different barrel twist depending on what u go with but thats pretty much it.
Most of your recievers are going to come from the same places like Cerro Forge, FNMI or Colt then they are just marked for the company who buys and finishes them.
Most lower parts kits are all identical unless your installing a Geissele trigger or something similar (you’d be suprised how many companies use DPMS lower parts kits in their rifles) so there’s nothing to worry about there.
Most barrels are going to be either Mossberg, ER Shaw, DPMS or FN
Remember that all these parts may have a certain name stamped on them but that doesn’t make them different from most of the other parts out there that may have come from the same place or at least manufactured using the same proccesses and equipment to create those parts to the same milspec/industry standard.
The biggest issue with buying an AR has nothing to do with parts ……… its all about assembly, pick a company that has a good reputation for assembling rifles the right way, who MPI & HPT test there parts and who have a good customer service/warranty service. Some of the best companies in those catagories are suprisingly DPMS & Spike’s Tactical (although I know alot of people think Spike’s is overrated ….. they do have great customer service and they test all their parts, not just batch test)
As far as options go, a few of the bigger options that you’ll want to take into consideration are barrel twist, barrel & gas system length, chrome lined vs non-chromed lined barrel and barrel contour.
The twist rate is going to depend on what weight ammo your shooting, since the most common, most available & most affordable round is going to be 55 grain I’d recommend a 1:9 twist (which basically means that the rifled grooves in the barrel that spin the bullet make one complete revolution around the inside of the barrel every 9″ inches ….. a 1:7 would be every 7″ inches) getting a 1:7 twist works better for heavier bullets like the 62 grain.
As for the chrome lined vs non chromed lined option, thats a personal choice. Chrome lined usually tend to be easier to clean, have better extraction and if u use alot of different loads on your rifle it can help with reliability. Non chromed lined barrels are going to be more accurate but reqiure a little more effort to clean.
Now for the barrel/gas system length decision, this is one that has so many options that its an article in and of itself. The most popular and reliable will be the 16″ barrel with a carbine length gas system or the 20″ barrel with a full length gas system.
Lastly the barrel contour decision has just as many options if not more than the barrel length and gas system options but the standards are …….
M4 contoured barrel (most popular on the 16″ carbine version)
Bull/Varmint barrels (great for any length but mostly for target or small game shooting)
Heavy barrel (a good solid barrel that has a bit of a longer life than most but adds a bit of weight to the front end)
Light or “pencil” barrel (great at weight saving but if your an active shooter I wouldn’t recommend this as its has a shorter life as far as round count goes)
Remember that you don’t have to spend $1500 bucks to have a good quality AR and building one yourself can definitely help save you some money on a quality build.
Well there you go, those are the basics as I see them, hopefully it helps out a little when making your decision to buy or build your AR rifle.