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Make your AR 'buffer': a different buffer and adjustable gas block might just be what your carbine needs to run its best.

Of all the parts on an AR-15, the buffer is perhaps the most insipid. It spends its life hidden in the receiver extension, and when pulled free it does little to cause excitement. Flat on one end, round in the middle with a 'thingy' on the Other end, it's rather boring to look at. Shake it next to your ear and you'll hear 'something' rattling about inside. But what does it do and how can it be hot-rodded to your benefit? To find out lets pop a standard carbine buffer apart and let the magic smoke out.

To do this you only need a punch and a hammer. Drive the retaining pin out, pop the synthetic pad off and peer inside. You'll find three steel weights and three rubber pads. Placing the pieces on a scale you'll find a standard buffer to weigh three ounces assembled. The three steel weights and three rubber pads weigh approximately 1.9 ounces. So what does your buffer do?

To operate reliably with a diverse array of loads in conditions ranging from extreme heat to extreme cold--even when dirty--requires a careful balancing act. An AR needs to have enough gas tapped off to cycle the action forcefully but not excessively. If too much gas is tapped off felt recoil and wear on the mechanism is increased. If too little is tapped off the action will not cycle properly leading to malfunctions, failure to feed or failure of the bolt to lock back on the last round. Typically a factory AR carbine will normally be a bit over-gassed to ensure reliable function even in extreme conditions.

While being a bit over-gassed aids reliability it is not always advantageous or even desirable. This is especially true for recreational use or for various types of competition where a lighter recoiling and smoother operating cycle is desired. For such use it is possible to tune how the carbine cycles by adjusting the weight of the reciprocating mass. Simply increasing the weight of the reciprocating mass can provide some noticeable benefits including reducing felt recoil, muzzle movement and providing additional mass to aid feeding during the loading cycle. The easiest and most cost effective way to do this is to simply replace your standard buffer with a heavier model. This is not only very easy to do, but requires no tools. You simply ensure your firearm is unloaded, remove the magazine, push the rear take-down pin through and pivot the upper receiver. Next depress the buffer detent and the buffer and spring can be easily removed by pulling it out of the receiver extension. After this you can easily separate the buffer from the action spring.

Luckily carbine buffers are available in a variety of weights. Colt developed heavier models for certain applications including the HI (3.8 ounces), H2 (4.6 ounces) and H3 (5.4 ounces). Plus, Colt developed one for 9mm submachine guns (5,5 ounces). Whereas the standard carbine buffer utilizes three steel weights the H1 uses two steel weights and one tungsten weight, H2 Uses two tungsten and one steel weight while the H3 uses three tungsten weights. The 9mm buffer uses a different and heavier body. So it's possible to tune how your carbine cycles by simply swapping to a heavier buffer. If you go too heavy though, your carbine will fail to cycle properly.

Buying a bunch of different buffers can be a waste of hard-earned money if you only need one, right? Well if you have a standard buffer and you buy an H3 buffer you can use their weights to build both an H1 and an H2. Keep in mind they come apart fairly easily with a punch and hammer. Also note the moving internal weights are intended to provide a 'dead-blow' hammer effect to eliminate bolt bounce (very important on full-automatic).

While Colt's 'H' series are the most common there are also other weights and designs available from the aftermarket. My favorite, which I have used for years, is MGI's Rate and Recoil Reducing buffer. The MGI buffer features tungsten weights providing a heavy 7.1 ounce weight combined with a spring loaded shock absorber. Its 7.1 ounce weight (over twice as heavy as a standard buffer) provides a slight delay in bolt unlock timing. This provides extra time for the swelled case to release its grip on the chamber wall, aiding extraction. The bolt/carrier/ buffer's rearward movement is also at a slower rate due to the increased weight. When the MGI buffer strikes the rear of the receiver extension its mechanical plunger propels the internal tungsten weights forward. These contact the rearward moving buffer body (internally) and cause a cancellation of the rearward movement just prior to bottoming out. The masses then come to a complete stop, eliminating some of the felt recoil that would otherwise be transmitted to the shooter. When the recoil spring drives the buffer/carrier/bolt assembly forward it is at a slower speed due to the greater mass. This provides additional time for the magazine to present the next cartridge. However it has greater momentum due to the increased weight, which aids feeding. After the bolt locks the MGI's internal tungsten weights provide a follow-up hit into the front end of the buffer eliminating bolt bounce. A very, effective unit, felt recoil is noticeably reduced in a semiautomatic rifle and a drop in cyclic rate of 20 to 25% is typical on full-automatic. The only downside is cost. At $165 it's not cheap, but it is effective.

Another option is to peruse, they offer a wide variety of AR buffers, 9mm buffers, AR-10 buffers along with special designs for Vltor's A5 system and LWRCI's UCIW short receiver extension. Of interest to us is their HSS model which features a stainless steel body, tungsten weights and beefy 6.5 ounce weight. Their XH model is the heaviest on the market tipping the scales at 8.5 ounces, almost three times the weight of a standard unit. Both the HSS and XH are machined from solid 303 stainless steel and sport a smooth polished finish. They are assembled using tungsten anti-bounce weights, stainless steel roll pins and synthetic pads. Very nicely made and quite effective I recommend considering them. Price is $75 for the HSS and $125 for the XH. Keep in mind that adding weight to the reciprocating mass is just one possible solution. It just happens to be the easiest method.

Another route preferred by competition shooters is to replace the standard non-adjustable gas block with an adjustable unit, allowing them to dial the gas down. Reducing gas introduced into the system allows weight to be removed from the reciprocating mass while still maintaining a proper 'balance' for reliable function. The lighter reciprocating mass reduces felt recoil providing quicker recovery between shots. Keep in mind though; you must have an adjustable gas block if you wish to remove weight.

The basic concept is relatively simple. A valve of some type is used to regulate the flow of gas providing a sufficient amount to operate the rifle's mechanism. Of course the engineers designing a multiple-setting system have to walk a fine line. Too little gas allowed into the system will result in short-stroking and unreliability. Too much gas tapped off will cause too violent of an operation leading to other problems and possible parts breakage. So there is a balancing act.

Now keep in mind that adjustable gas blocks are nothing new. They have been around since the dawn of gas-operated systems. Perhaps the best known rifle design with an easily adjustable gas block is Fabrique Nationale's famous 1950s vintage FAL. The large number of settings of this design allowed a well-trained rifleman to tune his rifle to the ammunition and conditions. However it also provided something for the inept or untrained to fiddle with. Mindlessly playing with the FAL's gas regulator can turn the flow down to the point where the rifle ceases to function. It's this 'lowest common denominator' that had led many of the world's militaries, such as the Russians and Americans, to historically eschew easily adjustable gas blocks.

America's darling AR-15 does not make use of a user-adjustable regulator. Even so the genius of Stoner's system makes it remarkably reliable with a wide variety of loads/bullet weights in diverse conditions. What works well for a service rifle though is not always optimum for a competition gun. Over the decades many competitive shooters looking to optimize the performance of their AR-15 have delved into fitting an adjustable gas block to their rifle. Why? Most gas operated rifles, especially Kalashnikovs, tend to be very over-gassed meaning they tap off more gas then they actually need under normal conditions. Basically they are gassed for a 'worst case' scenario. By reducing the amount of gas flowing into the system it is possible to reduce the firing impulse and movement of the rifle. How is this possible? Basically the velocity of the bolt carrier and buffer assembly is reduced, both going to the rear and back forward. The end result is a smoother and softer-shooting rifle that is easier to control and make rapid follow-up shots with.

An adjustable gas block will allow you to take an over-gassed rifle and optimize the setting. It will also allow you to tune the rifle for a specific load, such as a light-recoiling 55 grain .223 Rem handload. This can be very important for certain types of competition where speed is the name of the game. While some gains can be made simply by adding an adjustable gas block to a stock gun, they are small. To reap the full benefit of an adjustable gas block, you must reduce the reciprocating mass. In my opinion, switching to a lightweight bolt carrier assembly and lightweight buffer allows an adjustable gas system to really come into its own. The gains here can be impressive. Many times I've handed an AR with an adjustable gas system and lightweight internals to another shooter and they are shocked by how smooth shooting and easy to control it is.

If I've perked your interest, be aware there are a number of different makes and styles of adjustable gas blocks available for AR rifles. Some have a simple screw adjustment. I'm not a big fan of these. A step up are those, such as offered by Wilson Combat, which have both a screw adjustment along with set screw to lock the adjuster in place. With this style you make your adjustment with an Allen wrench and then you lock it into place to prevent your setting from changing. It's simple and simple is often best.

Speaking of simple, Patriot Ordnance Factory (POF USA) recently introduced its Dictator Adjustable Gas Block. It's available in either carbine- or mid-length models, and has nine settings that allow for just about any setup to operate smoothly and reliably. A unique feature of this block is the straight gas tube. POF claims that removing the kink in the tube reduces heat build up, something that is especially common when running a full-auto or suppressed gun. It's a compact model that only requires .5" clearance to fit under a Picatinney rail. Each Dictator is supplied with a special tool to adjust the flow, but a flat screwdriver or 3/32-inch hex wrench will do the trick, too. Price is set at $179.99.

One design that stands out is offered by Todd Gardner of SLR Rifleworks. Gardner's design sports repeatable click adjustments. So you can count clicks and have multiple easily repeatable settings for different loads or conditions. They are very well thought out and stand distinct design-wise from the crowd. Each gas block is machined from heat-treated 4140 steel. They are then fitted with a 316 stainless steel detent plunger, 6AL-4V Titanium leaf spring detent mechanism and a Nextum Swiss metering screw. Take note, SLR's design eliminates tiny coil springs and ball bearings which can corrode, break or seize. I like this. The design provides 100% gas cutoff when closed as well as audible and tactile adjustment clicks. Complete disassembly is very easy and straight forward.

SLR Rifleworks offers both clamp-on and set-screw models in .625, .750 and .935 inch diameter. They also offer a clamp-on model in .875 inch. I installed a .750 inch set screw on a 16 inch 5.56x45mm carbine with a midlength gas system without any issues. It is very well made and nicely machined. Adjustments are consistent and I ran the rifle both with a standard M16 bolt carrier assembly and 7 ounce MGI buffer as well as a lightweight skeletonized bolt carrier assembly and 2.75 ounce buffer. I had zero issues dialing in the gas flow for a variety of loads ranging from 55-grain Wolf to 77-grain Mk 262 Mod 1. With the lightweight carrier and buffer I was able to dial the gas flow back to provide exceptionally smooth cycling and light recoil with 100% reliability. I have to say I love the way this carbine performs now. Does everyone need an adjustable gas block on their AR? No. Will it provide miracles by itself? No. I think most are best off with the standard design. However an adjustable gas block can be a highly useful item for tuning a rifle with lightweight internals. My personal pick is SLR Rifleworks' design priced at $114.99.

OK, say you switch to an adjustable gas block and a lightweight bolt carrier assembly, what about your buffer? Instead of going heavier the trick is to go lighter while still maintaining your desired level of reliability. If you wish to go lighter than a standard buffer you can remove some or all the weights. If you wish to go even lighter that's possible too. One option is Taccom's LW AR-15 recoil system which features a delrin buffer weighing less than 1 ounce. Now that's light! Price is $22.95 for a carbine and $24.95 for a rifle-length buffer.

Keep in mind, there is a downside to ultra-light bolt carrier assemblies and buffers. Simply put, they lack the momentum of heavier units at the same velocity. So while they are easier to start moving, they are also easier to stop. This can lead to problems when a rifle is very dirty or fouled, especially when trying to strip a round from the magazine. Remember, there is no free lunch. The quick fix is to turn the gas up to add additional velocity to the moving parts.

My final thoughts? If it's a firearm intended for self-protection it's often best to just leave it alone. Being a little over-gassed isn't a bad thing. Now, if it's for recreational use, then that's completely different. If it's over-gassed and you don't have an adjustable gas block adding a heavier buffer can noticeably reduce felt recoil. If you do have an adjustable gas system reducing weight can do wonderful things. Don't be afraid to experiment and have fun with Stoner's wonderful creation.



MGI Industries, Inc.--207-817-3280,, www.

Patriot Ordnance Factory--623-561-9572,

Spike's Tactical--407-928-2666,

SLR RifleWorks-855-757-7435,



No problem, can bulk up your girly-man buffer.

When it comes to buttstocks for short barrel rifles or ultralight ARs, one of my favorite Is from LWRCI. Their Ultra Compact Stock Is a great piece that reduces overall length, size and weight without compromising usability. It Includes not only the stock but a receiver extension, buffer and spring. All these parts are proprietary and designed to work together. When I first bought my Ultra Compact Stock my only wish was for a bit more variety In buffer weights. Yes, the stock LWRCI 3.2 ounce unit works very well, but in certain applications a heavier buffer might offer advantages. So my interest was perked when I learned offered two aftermarket units for this application. Developed especially for the LWRCI Ultra Compact Stock with its short receiver extension, their Extra Heavy UCIW Ultra Compact Buffer weighs in at a hefty 5.5 ounces. Machined from solid 303 stainless steel It sports a smooth polished finish. To increase the weight it is assembled using tungsten anti-bounce weights. It's finished off with a stainless steel roll pin and synthetic pad. If you have fitted an Ultra Compact Stock onto a 9x19mm AR, also offers a special longer and heavier buffer specifically for this application. Called the U-9 it weighs in at 8.5 ounces. Both are designed to work with action springs offers. The UCIW buffer and spring combo is $140 and the U-9 buffer and spring is $150. Not cheap for sure, but a nice option if you need the extra weight. They also offer buffers for 9mm ARs, AR-10s and Vltor's A5 system.


Make the job easier

If you are replacing a gas block, Geissele offers a couple tools you might be Interested In. Their Gas Block Pin Punch set is made specifically for the removal and Installation of the 0.078-inch roll pin that secures the gas tube to the gas block. Removal of a rusted roll pin can be a pain as there are no commercial pin punches In 0.078-inch diameter. Geissele developed a two-piece set specifically to make this job easy. It consists of a robust tapered starter punch and a properly sized pin punch. The long taper makes the starter punch resistant to bending, so its job is to get a stubborn pin moving. Once you get it moving, swap tools and drive the pin out with the pin punch. Both pieces are machined from properly hardened and tempered 01 tool steel and look nice. While neither are glamorous nor something you will Impress your friends with, it's a very handy set to have if you work on ARs. Price is $25.

Geissele also offers a gas block roll pin tool for installing the roll pin. This is a handy unit that holds the roll pin to get it started. It's made so you don't have to try to hold the tiny roll pin while tapping It into place. To use, simply seat the roll pin into the nose of the tool. Next, tap it into place until It's started and held by the gas block. A tap or two is all that's needed. Once the roll pin is started, remove the tool and properly seat the roll-pin with a punch. It's quick, simple and makes life easy. As expected the tool is nicely made and priced at just $12.50. Do you need it if you're building just one AR? No., But it's a nice luxury to have if you work on ARs fairly often.
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Author:Fortier, David M.
Publication:Shotgun News
Date:Sep 10, 2015
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