Did you know that replacing the factory gas block on your AR-15 with an adjustable gas block can improve your rifle’s performance? Such as:
Less recoil, results in a faster follow-up shot
Less stress on the operating parts
Less carbon build-up, better reliability and easier cleaning
JP Adjustable Gas Block (JPGS-5B) under an aluminum forearm. The forearm is a Rainier Arms Keymod Force rail. The muzzle device is a Primary Weapons Systems FSC-556 compensator.
What is a Gas Block?
The JP Adjustable Gas Block under a free-float aluminum forearm.
The typical factory gas block is pinned onto the barrel in front of the polymer handguard as part of the front sight assembly. If your rifle features a free-float aluminum handguard, then the gas block is typically a low-profile type that fits under that handguard. The job of the gas block is to take some of the hot gas from behind the bullet that comes through a gas port in the barrel, and direct it into the gas tube which drives the bolt carrier and cycles the action.
Most gas blocks on factory AR-15s are fixed, meaning they just provide a path for the gas from the barrel to the gas tube. With a fixed gas block, all the gas and pressure that comes out of the gas port in the barrel will be used to cycle the action.
In most AR-type rifles there is intentionally more gas than needed, so that if the gun gets dirty, it will continue to cycle.
But often this overgassed situation is more than is really needed, adding to the recoil and increasing wear on parts. That’s where adjustable gas blocks come in. They provide a way to cut off a portion of the gas flow so the action can be driven less forcefully.
The Gas Block History
Three adjustable gas blocks: Syrac Ordnance, JP Enterprises and SLR Rifleworks.
The concept of an adjustable-gas system has been around for quite a while. Competition shooters using M1 Garand rifles, a semiauto first used in the US military in 1936, found utility in adjustable gas plugs to regulate the cycling of the action by letting out a little extra gas.
Perhaps the most prolific use was in theFN-FAL (Fabrique Nationale-Fusil Automatique Légerseries, a Belgium manufacturer) rifles developed after World War II. On the FNs, the amount of gas released out of the gas cylinder as the piston was cycling could be adjusted by hand, which controlled how much gas pressure was applied to the piston.
This is similar to what the M1 competition shooters were doing with their adjustable gas plugs.
The normal procedure is to tune down the gas pressure until the gun doesn’t fully cycle, then tune it up one click at a time until it cycles reliably, then go a few clicks further for reliability and you’ll be in the optimal zone. This way the gun is reliable with the least amount of recoil and stress possible, and it can be tuned to a specific type of ammunition as well.
Gas Blocks Today
The JP Adjustable Gas Block (model JPGS-5B) on a barrel.
This same concept is now being applied to the AR-15 and AR-10 family of rifles with modern adjustable gas blocks. The difference is on an AR-15 the gas adjustment cuts off some of the gas flow coming from the barrel instead of letting more of it out after it passes through the gas block, as on the FN-FAL and M1. Early adjustable gas blocks on AR-15s simply used a small metering screw on the side of the gas block that cut off gas flow as you screwed it in. The further you screwed it in, the less gas flow there was.
Once adjusted, the screws were kept in place either by using Loctite or by just letting some carbon build up on the screw to hold it in place. This worked pretty well in practice and has been used by AR-15, 3-Gun shooters for years, but didn’t gain wide acceptance. In the past few years new designs have emerged that have taken the concept to the next level and improved shooter appeal.
Brass locking screws have been added to ensure adjustments stay put without using Loctite, and low-profile versions have been made so they can fit under free-float forearms. Designing them to fit under most of the popular rail systems is a big plus for modern AR builders. Eventually, the desire for lockable settings was solved with spring-loaded detents that were used to lock adjustments in place with audible clicks.
This made it possible to adjust the gas block under the handguard in the field by a known amount and have it automatically lock in place. For those wanting a more mil-spec (military specification or standards) type solution, this was very appealing and has brought these adjustable gas blocks into a far wider acceptance.
You’re probably wondering what difference would it really make in your gun’s performance if you used one of these. Well, there are three:
JP Adjustable Gas Block (JPGS-5B) mounted forward of a free-float JP VTAC Modular hand guard, instead of underneath it, so the gas tube can be seen. The muzzle device is still a PWS FSC-556.
1) You can tune your rifle to run just as hard as is really needed, and by doing so you will experience less recoil and less movement of your sights off target, so your follow-up shots can be faster. What’s happening is that your bolt carrier group will cycle hard enough to extract, eject and feed reliably, but it won’t slam to a stop as hard at the rear of its stroke.
2) There will be less stress on your operating parts because they are not running any harder than necessary. It’s like running your car engine at lower revolutions per minute. Don’t worry, it will not feel slower while shooting.
3) Since you will be cutting off some of the gas going into the bolt carrier group, it’s common to get less carbon build-up in your bolt carrier and on your bolt. This will cause your gun to run cleaner, which can result in better reliability and easier cleaning.
All of these benefits are worthwhile for the shooter who wants to get all the performance possible from his or her rifle.
The SLR Rifleworks adjustable gas block on a barrel.
So how easy are they to install? If you are familiar with AR builds and installing gas blocks, then installing one of these is the same thing.
For those unfamiliar, it will require removing your flash hider or muzzle brake, removing your handguard, unpinning and removing your factory gas block and installing the new one using set screws or clamping screws to lock it into place. Then you reinstall your handguard and muzzle device. These days, with all the AR-15 home builders out there, this is pretty common knowledge, and the skills required are basic-level gunsmithing.
If you aren’t comfortable with this, find a reputable gunsmith who is proficient in AR builds; this will be an inexpensive gunsmithing job. There is no fitting required; it just involves taking off some parts and then reinstalling some parts. Adjustable gas blocks can be installed on any AR-15 or AR-10 rifle of any caliber or barrel length, as long as it uses a standard gas tube system. ASJ
Editor’s note: Brian Hormberg is the owner of Para Bellum Products, Inc. You can visit the company’s website at nokick.com or follow his blog at ontarget-blog.com.
By Brian Hormberg
One of the pioneers in the adjustable gas block concept is JP Enterprises, a well-known manufacturer of top-of-the-line race guns for 3-Gun competition. They made an entire system of it by combining adjustable gas blocks with low-mass bolt carriers and low-mass buffers. This concept called for lower reciprocating mass in the moving parts which needed lower gas pressure to run at the right speed. Adjustable gas blocks made this concept possible. The result is even less movement of the gun during firing and even faster recovery from the shot, which is a big advantage in competition. Low-mass systems are normally recommended for competition guns versus duty guns, since a full-mass system can run better when really dirty.
JPmakes their adjustable gas blocks in several formats, including ones with rails on top of the gas block, fixed front-sight models, and low-profile units with lock screws that go under handguards.Syrac Ordnance and SLR Rifleworks are two companies that have recently introduced low-profile, click-adjustable models that can be easily adjusted from the front under the forearm. These are especially well suited to those who want a quick, predictable gas setting change when they switch from subsonic to supersonic or when going from suppressed to unsuppressed. The Syrac Ordnance model is completely self-contained, while the SLR Rifleworks model is designed for easy disassembly and cleaning. Both are small enough to fit under the thinnest aluminum forearm systems.
Another recent trend is to offer this same capability in a piston-driven format in addition to the more common direct gas design. If you like the idea of a piston-driven operating system and like the idea of adjustable gas settings, you can now have both together. The adjustable piston systems can be retrofitted to existing AR-15s or included in new builds just like the other gas blocks and provide the same advantages. The adjustable piston systems include a gas block, gas piston and a complete bolt-carrier group, in addition to the gas block itself to ensure compatibility. Low-profile versions are now in production fromAdams Arms and Syrac Ordnance, and which allow you to fit an adjustable gas piston system under a wider selection of rail forearms than ever before possible and with the adjustment capability.
As more shooters become aware of the advantages of adjustable gas systems, they will likely continue to increase in popularity. All of this is another example of the incredibly wide selection of parts, designs and options available to today’s AR shooter. The operation and performance of the rifle can be customized and tuned to an amazing level, and is only limited by your imagination.
Here’s some tips for tuning your AR-15 adjustable gas block from Jesse Tishcauser of Optics Planet.
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We can all agree that AR’s are not only reliable but are great at short ranges from 0 to 300 yards.
But what if you want to reach out further to 400 yard or 1000 yards? For the larger cartridge would the AR be able to deliver the same punch as its cousin the .308 or 6.5 Creedmoor?
Before making the decision to go with an AR10 or AR15, lets take a look at the comparisons.
The AR10 rifle is an air-cooled lightweight rifle that is gas operated and comes with the 7.62mm (.308) barrel.
uses the standardized 7.62x51mm loads and has a standard 20-round detachable magazine box.
It weighs between 3.29kgs and 4.05kgs, without the magazine and ammo. The super-lightweight feature was as a result of the use of aluminum alloy.
The metal parts were save for the steel bolt, barrel and bolt carrier group.
With its direct gas impingement mechanism where the propellant gas goes through the rifle’s cylinder that runs parallel with the gun barrel thereby impinging the bolt carrier mechanism.
This produces a high cyclic fire rate of about 700 rounds per minute with a 2,772 FPS/ 845 m/s muzzle velocity.
This rifle employs the same “direct gas impingement” as the one used on AR10s.
Which results in 800 rounds per minute from this gun, with a muzzle velocity of 3200 FPS or 975 m/s being realized to a maximum effective range of about 600 yards.
Whereas the AR10 features the .308 Win or 7.62x51mm NATO chamber, the AR15 features the .223 or 5.65 x 45mm chambers.
In the AR10 platform, it is unsafe to load the .308 in a 7.62x51mm chamber but the .308 chamber can accept the 7.62x51mm loads. Similarly, you can load .223 cartridges in a 5.65 x 45 chamber of the AR15 but not the inverse.
For those using both AR’s, here are some parts that are commonly interchangeable between the two:
The buffer tubes of AR-15 and AR-10 are usually the same in diameter.
Having a quality buttstock allows comfort and can improve your shooting.
Even with though the lowers on both AR’s are different sizes, the triggers
are still interchangeable. The mechanism on both are the same.
Buffer Detent and Spring
These small parts holds the buffer of the weapon in place.
Just a note the buffer itself is not interchangeable.
Good thing its the same on both AR’s.
Magazine Release Button and Spring
Even though the catch is different, the release button and spring are same.
Same size pistol grip
Who’s the Winner?
This is a question that is nearly impossible and hard to answer.
The reason is that these are both quality rifles that gives the users many advantages when using the AR platform.
So determining which one is the clear winner would definitely have to factor in how good the user is.
They both are lightweight rifles that used advance gas impingement systems to increase their rate of fire and muzzle velocity.
Each one also has a variety of ways in which they can be configure. This allows them to be tailored to meet each individual shooters needs.
As far as hunting big game goes the AR-10 most definitely would have the advantage over the AR-15.
In a wide open shot situation its extra length would not be much of a factor.
It also has greater one shot stopping power than the AR 15 does. Its heavier bullets can travel long distances fairly accurately too.
In a tactical situation the AR-15 definitely will give you the edge. AR15 is lighter and more maneuverable than its AR 10 predecessor.
It’s deadly accurate over shorter distances. The high rate of fire and increased muzzle velocity will also allow you to put many rounds into a target at a faster rate.
In short neither of these weapons has any major drawbacks that would prevent you from using them for hunting, target shooting or in a personal defense situation.
They both are accurate and rapid shooting weapons that are extremely deadly in the hands of a skilled shooter.
That is why there is no clear winner to be found between the two AR’s.
Aero Precision’s M5E1 is an evolutionary improvement on the basic AR-10 theme.
[su_dropcap style=”flat” size=”5″]T[/su_dropcap]he Aero Precision M5E1 is a logical development from their more basic M5 .308 autoloading rifle. It is positioned as a firearm that’s practical in the field, yet more accurate and capable of sustained fire than typical hunting or defense rifles. The main upgrade is the strengthened receiver designed to give monolithic-rail effects without its logistical disadvantage, namely the difficulty of changing the forend. The area where the freefloated handguard and the barrel attach to the receiver has been beefed up relative to the typical AR-10-style guns. The mounting surface for the forend is machined into the upper receiver, so the free-floated rail attaches with just four pairs of screws and no need for additional rings or hardware.
Its realistic niche is for a designated marksman or a hunter working from a blind.
The creation of this rifle was driven by the need for a relatively handy rifle that yields maximum muzzle velocity.
The rifle I tested was a combination of all three variants offered by Aero Precision. It came with an adjustable Magpul CTR stock designed for the 16-inch carbine, a 15-inch forend for an 18-inch midlength rifle and a 20-inch barrel for a full-length rifle. The goal was to have a relatively handy weapon yielding maximum muzzle velocity. A variable-length stock allowed adjustments for various shooting positions and for body armor. Of the two colors available, I chose the flat dark earth cerakote, mainly to reduce the gun’s visibility and its tendency to warm up in direct sunlight during hot Tennessee summers. The edges of the receiver and the forend have all been carefully chamfered and smoothed, making gloveless handling comfortable. Extensively ventilated KeyMod handguards with a full-length Picatinny top rail proved well suited for field use, requiring only a short rail segment up front for the bipod, or a direct KeyMod bipod stud. The stock offered a quick-detach socket on both sides, and the QD rail-mounted receptacle for the front of the sling completed this field-ready rifle.
The edges of the receiver and the forend have all been carefully chamfered and smoothed, making gloveless handling comfortable.
In cold weather, the all-metal forend would be insulated with rail covers, while in warmer weather, free air flow around the barrel would take priority. Due to the long barrel, the rifle starts out front-heavy, but adding a scope and a full 20-round magazine brings the balance to the front of the magazine well.
In keeping with the intended use of this rifle, I put a 1-6x Vortex Razor HD scope on it. With the optic set to six power, the M5E1 can be used to engage goblin-sized targets out to 600 yards from a bipod or an improvised rest. At intermediate magnification, it’s excellent for unsupported shooting. And at true 1x with daylight-bright reticle illumination, it works as an expedient red-dot sight for tracking motion. A rifle-length barrel with a flash hider keeps muzzle flash from showing up in the field of view, even in low light. The same length and the attendant inertia keep the muzzle rise to a minimum, so shooters can spot their own targets through the scope at all magnifications. The recoil is negligible, allowing full concentration on marksmanship without concern for the kick.
The area where the freefloated handguard and the barrel attach to the receiver has been beefed up relative to the typical AR-10-style guns.
The rifle functioned reliably with over a dozen types of ammunition, from steel-cased ball to hunting soft points and match hollow points. The trigger is smooth during take-up, with a crisp breakpoint but still at military standard weight. Running it in winter gloves, I came to appreciate it for the tactile feedback it provided. The enlarged integral trigger guard helped make gloved use safe.
My M5E1 was test fired from a rest at the factory on my request, grouping around 1 minute of angle with Federal 168-grain Gold Match ammunition. All of my testing was conducted by a former Marine Corps rifleman under less formal conditions from sandbags or from a Lead Sled, usually with some crosswind.
The shooters remarked that they considered the rifle capable of better precision than it demonstrated, though I am convinced that 0.75 MOA is quite respectable, especially when the limitation of the six-power scope is considered. The barrel twist rate is 1 in 10, optimal for 175-grain bullets, while the older 1-in-12 standard works fine for the 168s. For short-range plinking or CQB training, the difference in mechanical accuracy would be of negligible importance, but heavier bullets would work best for deliberate long-range precision work. With initial muzzle velocity around 2,500 feet per second, most 175-grain loads stay supersonic out past 1,000 yards – well outside of the optical range of our setup.
The trigger is smooth during take-up, with a crisp breakpoint, but still at military standard weight.
The fit and finishof the rifle are excellent. Internals showed almost no visible wear after the first 400 rounds. While the lower has a threaded opening for a tension screw, I found it unnecessary because play between the lower and the upper was already negligible. I would have preferred an extended charging handle latch, but that’s an easy fix.
The rifle weighs 9.6 pounds empty, on par with an M1A match or FN FAL. Loaded and scoped, it tips in at 13.6 pounds. Its realistic niche is for a designated marksman or a hunter working from a blind. Despite the weight, the gun travels well slung, thanks to the absence of any protrusions. The M5E1 is an evolutionary improvement on the basic AR10 theme, and is a very enjoyable to operate and unfailingly reliable. With the recent price drop bringing the complete gun to the $1,300 to $1,600 range, depending on the variant, it is quite competitive with other precision alternatives. And that has long been Aero’s chosen field, good performance at a reasonable price. ASJ
Theres probably lots of you gun hobbyist/hunters out there that have built your own AR’s.
Not all of us have done this.
Johnny Muller, of Kansas City, built an AR-10, by piecing together components and a little instruction from his military buddy.
To start, he got a builder kit from Aero Precision to use as a base and then pieced together his custom rifle using his favorite parts.
This included Magpul furniture, a Geissele trigger and a VG6 7.62 muzzle brake.
For optics, Muller chose the Nikon M-308 with BDA reticle and 20-MOA mount because he was impressed by how well the scope zooms and held it’s zero despite being bumped around.
Now that he’s got his first rifle build under his belt, he said he would encourage others to do the same.
There’s nothing better than shooting your own rifle that you built with your own hands. It’s really rewarding.
He’s happy of his rifle, on his first evening out hunting with it, he tagged two deer, both around 350 yards away.
[su_heading size=”30″]Will the military grade ballistic plate stop these rounds? [/su_heading]
[su_dropcap style=”flat” size=”5″]W[/su_dropcap]atch as Jerry Miculek pits an AR-10 .30 cal against body armor with some high-volume rapid fire. Jerry is trying to duplicate what Richard Ryan of Full Mag did, and that is he fired a .30 cal machine gun at a piece of armor. Jerry will be using the same cal with an AR-10 with the standard NATO 7.62 ball 147 grain rounds.
There it is, the plates were able to absorb the hits against it, round after round. There is a reason modern light infantry and combat soldiers wear integrated soft-body armor and plates. It allows troops to absorb unbelievable strikes and survive. Fifty years ago, no soldier would have survived this many direct hits to the chest and vitals; today’s warrior can survive and even get back into the fight.
The downside in the last twenty years is the weight a combat soldier has had to carry; the body armor alone could weigh up to 20 pounds. Add this to weapons, magazines, grenades, med kit, water, small-pack and the average grunt could be humping 77 pounds or more. An energy sapping load, especially in the heat of Iraq or Afghanistan. Thank goodness technology advances and body armor is weighing less and less; which is a good thing if you are the ground-pounder.
Hey guys, I’m Jerry Miculek, and what I’m tryin’ to do today is to duplicate what Richard Ryan did with Fullmag, on his minigun attempt to shoot this piece of steel. And he’s had this thirty-caliber minigun, and it’s shooting about three-thousand rounds a minute, and what he did was fire on that piece of steel, you see downrange, and he put about four hits in it, and appeared to hold about three seconds before it fell to the ground, so I’m gonna try to duplicate that. I’ve got a thirty-caliber M&P10, Same caliber, 762×51 NATO. I’ve got some standard 147-grain 30caliber ball, and I’m gonna turn around and on the clock, I’m gonna see how many times I can hit that target before it flips over or leaves. So uh, let’s see what that looks like!
Alright! Eyes and ears! Heeere we go!
And it finally fell over! Haha! Alright, let’s clear it out! Alright!
We are clear!
I did fire twelve rounds, in exactly two-point-five-hundredths of a second! So let’s go see what we did.
Hey guys I got the target, I went downrange to get it, we had about sixteen inches of rain out here in the past week, so it’s kinda boggy, we didn’t wanna bring the camera down there. But anyway! To give you an idea of the total time from the first to my last shot -which was twelve rounds- was two-point-zero-five-one-hundredths of a second, and I actually struck the target five times. So my hit ratio was like a forty-one percent, so– which is not bad for full-caliber ammo at about twenty-five, twenty-eight yards. So I give you an idea what the hits are: We’ve got one here, two, three, four, and five. So we’ve got five hits on a target. One thing that I want to point out to you, this- the way this plate is made, it’s made for light body armor, so it has this protective coating on the front is actually made to be worn in a vest like this, and the idea of this coating is to stop a lot of the spalling from the round hitting the plate, and you can see on the bottom it’s starting to lift it off with five hits. But if you were wearing it on your chest, most of the spalling or the frag would be contained, and that’s one reason I got a little bit brave and got within about twenty eight, thirty yards of that target. Otherwise if that was bad(?) steel, light steel, I wouldn’t have done this. So the target withstood the beating, and what can I say about a 41% hit ratio? So, not bad for twelve rounds.
[su_heading size=”30″ margin=”0″]SHOT Show 2016 – American Shooting Journal winners[/su_heading]
Recapping an excellent trade show
The American Shooting Journal featured a forever-spinning raffle wheel that never stopped during the 2016 SHOT Show. The winners were endless, we couldn’t feature them all.
Brittany Boddington, international huntress phenom and Tom Claycomb, AMSJ survivalist contributor, visiting to sign autographs.
Louie Tuminaro AKA The Gunfather with veteran Jose Martinez whose image we felt earned the right to adorn the November 2015 veteran’s cover of ASJ and Theresa “T-Bone” Tuminaro grinningly signed autographs.
The American Shooting Journal SHOT Show booth was packed throughout the show. The raffle wheel never stopped spinning and shooting out great prizes to winners all day long.
Ulti-Clip was in the house. This little gadget redefines the idea of having a concealed holster and stole the show this year. We were thrilled to partner with them.
Savoy Leather makes custom leather holsters for all walks of gun toters. This Vietnam vet was thrilled with his loot from the raffle wheel.