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Lakeside Machine LM-7

During the ten year term of the Clinton Assault Weapons ban (1994-2004), joint firearms that were deemed “assault weapons” were prohibited from the manufacturer for sale to individuals. Also, forbidden were magazines and feeding devices with a capacity higher than ten rounds.

Machine guns. As the 2004 sunset of the ban got resembling, their focus switched to a line of newly created, shoulder-fired variants. Although the weapons could be manufactured in compliance with the ban, the low availability of belts for feeding them was very poor. With the ban terminated, more belt material was able to be manufactured, and a new generation of belt-fed rimfire rifles was born.

The first shoulder-fired, belt fed rifle system designed by Lakeside Machine was the BF1 Vindicator. Established in 2004, these rifles were manufactured in .22 Long Rifle with a some chambered in the relatively new .17 Mach II. These rifles used the same cloth belts designed initially for the Tippmann miniature machine guns and can also use the newly de-signed disintegrating links; another one of Lakeside Machines’ recent innovations. The disintegrating relationships are made of a Nylon material and function with .22LR,.22 Magnum, .17 HMR and .22 Mach II.

Above: Firing sequence – The extractor pulls a round from the belt. As the bolt travels to the rear the round is pushed downward on the T-slot in the bolt. When the bolt returns to the front, the round is chambered as the extractor collects the new round for belt extraction. As the process is repeated, the new round being pushed down the T-slot forces the fired round further down and out the ejection port.

In October of 2004, Eric Graetz, CEO of Lakeside Machine was approached by a customer and asked if he thought he could design an AR-15/M16 upper receiver that would accept his belts and links. Graetz took the challenge. After months of research and development, the machine shop was retooled to manufacture the latest creation: the LM-7 .22LR (and .17 Mach II) belt-fed upper receiver. The prototype was unveiled in December of 2004

At the SAR Show in Phoenix, Arizona. The LM-7 (the 7th model firearm Developed by Lakeside Machine) is a full upper receiver assembly that will fit on any regular AR-15 or M16 lower receiver & function with the trigger internals as intended. While appearing in a semiautomatic configuration, an upgrade is available to the upper will function in full automatic when used on a registered complete automatic lower receiver. To the delight of the NFA association, it will also activate in conjunction with a drop-in auto sear.

Mounting the LM-7

Before replacing the stock top receiver with an LM-7, the factory buffer and spring must be separated from the lower receiver and replaced with the new buffer assembly supplied with the LM-7. Due to inconsistencies in factory parts, Lakeside Machine has found that some hammer springs are much too heavy for LM-7 operation and they have designed an optional light spring to remedy this. The light season may be purchased separately if this concern should arise.

That is the extent of the modifications to the lower receiver when used on a semi-automatic rifle. When used on a fully automatic gun there are a few timing adjustments that may be necessary.

Installing the LM-7 upper receiver is as simple as pulling the two takedown pins, removing the factory upper and following it with the LM-7 top receiver. Once pinned on the junior handset, the company magazine-well now functions as a brass ejection anchorage. To catch the ejected casings, Lakeside Machine supplies a brass catcher that locks into the magazine-well in the same manner as a factory magazine. As it fills to capacity it can only be “ejected” like a standard magazine, the contents dumped out and quickly reinserted. The base of the brass catcher also has a swing-down floor plate to allow the empty brass to flow through when the shooter does not require to retain the ejected casings.

The brass catcher doubles as an attachment platform,For the optional belt box And link catcher. Shooting Long belts without the assistance of an A-Gunner can easily be performed with the use of the belt feed Box. It operates a little more than 200 belted or linked Rounds. Since the links are ejected directly across from the feed tray, another the same box mounted on the opposite side of the feed box catches all the used links.

The LM-7 functions in a similar style to a Browning Model 1919 Machine gun. It utilizes a shuttle feed the mechanism that feeds the belt, extracts Each round from the rear of the belt, chambers the round and extracts the empty case.

Above: The LM7 has a developed quick change barrel. To
barrels the buyer simply pushes its barrel release (arrow) & pulls
the barrel straight out. To insert a new barrel, the button is depressed and
the barrel is simply pushed in.

After firing. This mechanism does not utiLize a locked action. The rifle is loaded by lifting the top cover & inserting the belt With the first round set below the extractor. The top cover is closed, & the gun is charged with pulling the bolt handled Back and released one time. As a round is removed from the belt and loaded in the chamber, the fired case is pushed out of the T-slot in the bolt & dropped into the brass box or straight on the ground.The LM-7 uses an exclusive fast-change barrel (QCB) that can be replaced.In seconds.

Replacing or installing a barrel is as simple as depressing the barrel release button, pulling the barrel straight out, replacing the barrel and releasing them Button. It is a direct action that requires no twisting, turning, changing or head Spacing. Barrels are currently available in Two lengths & three styles. Barrel lengths Are 16.25 inches & 7.5 inches. The 16.25-inch barrels are shaped just like a standard M4 barrel & can utilize any Of the M4 mounting opportunities.

Where the barrels are secured in the receiver by the QCB mechanism, they are entirely free-Floating and will work fine with any free-Floating style handguard. If you wish to Use regular M4 handguards, you can use an adapter that secures them at the front and also doubles as a front sight Block. Since it is unnecessary for the front of the barrel to be supported by any Handguard mounting hardware, it lends itSelf-will to the use of shorter barrels with Sound Suppressors.

The 7.5-inch pipe we were shooting with was often fitted with an AWC MKII suppressor that protruded Less than 4 inches past the standard carbine handguards. If this policy were wanting to be set up in this configuration for regular use, the handguard would undoubtedly be replaced with a free-floating type or any of the rail systems supporting the use of Accessories.

On the rear of the top defense is a 4.25-inch M1913 Picatinny rail to accept short Optics or a removable rear sight. The first Block installed with a 16-inch barrel Includes a 1.75-inch track that can host stanDard removable front sights and access- Ries. The LM-7 we tested was provided with an EO Tech Model 552 Holographic

The masters of the small machine guns have just unveiled their latest creation. In just over a year from concept to production, Lake-side Machine of Pound, Wisconsin has announced the extension of the LM-7 to their rimfire lineup. The LM-7 is a belt-fed upper target chambered in .22 long rifle for an M16 or AR-15 type rifle.

This resulted in a cessation of various innovative designs and caused a sharp increase in price for existing stocks of weapons and magazines. There were many new armament concepts and pioneering ideas during this time, but with a market limited to the military and law enforcement, Sight. While the version using AA sets was a little long on this mount, it was probably still usable. While using the sight with multiple fast-change barrels, we noticed the tiny point of impact change. Each LM-7 order is shipped with the LM-7 Buffer System, a 16.25-inch barrel, front sight block, brass catcher, two provisions boxes, two 100-round belts and 200 links.

Rimfire Ammo Reliability

When the LM-7 was designed, it was built to work with the cheap CCI Blazer ammo. This is excellent news for shooters who are conscientious about their ammo means. We tested the LM-7 with different types of .22LR ammo and have included a chart indicating performance, muzzle velocity and rate of fire when utilized in whole automatic. The ammunition we tested included CCI Blazer, CCI Mini-Mag, CCI Stinger, Remington

Thunderbolt, Federal Bulk Pack, Federal Lightning, Federal Champion, and Winchester Wildcat. It ran fine with most, but the Federal Champion was the limited reliable. The absolute best was the CCI Stinger due to the increased power over standard .22LR ammo, but the additional cost (almost $4.00 for a box of 50) may be sufficient to discourage many people. The Winchester Wildcat, Federal Lightning, & CCI Blazer all worked great. The Federal Bulk Pack & Remington Thunderbolt also served quite reliably. For some reason, it was a few finicky with the CCI Mini-Mags. The author has found after years of shooting select-fire rimfire rifles and pistols, that when determining which

.22LR ammo will serve the best; it is usually an excellent idea to just try several brands in your firearm. Some seem to run
high on one particular name while other guns like something completely different. Factors that may be important in the LM-7 that would not indeed be an issue in other .22LR firearms include the width of the rim. After extraction from the belt, the round is led down a T-slot to the chamber and retaken in the T-Slot as it is channeled down to the point of ejection. If a particular brand or batch of ammo has a thicker than usual rim, it could interfere with, or stop, the operation of the gun altogether.

The most significant obstacle in reliable functioning is the lack of energy in the little.

.22LR cartridge. It takes a lot of energy to run these machines in full automatic, and when you start adding factors like pulling belts and links, the challenge gets even higher. Light parts and springs, necessary because of the low amount of energy created by the rimfire round, only add to bolt bounce problems and pose additional hurdles in the development of select-fire, Rimfire guns. Un-

Like many other select-fire .22 LR fire-arms, bolt bounce is not a problem in the LM-7 due to the function of the extractor pulling the new round from the belt at the same time the chambered shot is fired. This action dampens the rearward travel of the bolt and eliminates the bolt bounce issue.

With the weak .22LR ammo in thought, we can get into some of the timing issues when shooting the LM-7 in full automatic. Subtle differences that are not critical dimensions with higher-powered rounds can often be the determining factor in creating problems when shooting rimfire rifles. In the case of the LM-7, some of the loose tolerances of standard 5.56mm guns combined with the fact there are several manufacturers of rifles, receivers, and parts to fill them, create an enormous number of potential combinations.

When shooting the LM-7, the trigger role is identical to that of the original 5.56mm rifle. While shooting in semiautomatic mode, when the bolt carrier recoils from firing the chambered round, the hammer is cocked and held captive by the disconnector.

When the shooter lets off the trigger the hammer reports from the disconnector & engages the head of the trigger. When the killer squeezes the trigger, the hammer is released, and the process starts all over again. When shooting in fully automatic mode, the hammer bypasses the disconnector and does not contact it at all. A spur on the back of the stick is caught and held captive by the auto sear, and it is only released when the bolt carrier trips that sear when the gun has chambered the new round, and it is in a battery. The timing aspect comes into action with the connection between the bolt carrier sear trip and the sear releasing the hammer.

The part of the LM-7 that has to be altered for fully automatic fire is the bolt carrier. Just like the standard AR-15 and M16, all that is necessary for the upper receiver to accommodate a legally owned complete automatic lower receiver is the addition of a sear trip on the carrier.

Lakeside Machine will be happy to present owners of registered handsets or drop in auto sears with the piece needed to engage the auto sear. That is where the timing comes into play. The sear trip on the carrier needs to contact the auto sear at the precise time the new round is fully chambered. Due to a large number of parts and receivers on the market, one gun may need a specific thickness on the sear trip to engage the sear at the correct time while another firearm needs one much thicker. This timing can be accomplished by merely removing an Allen-head screw, removing the sear trip, adding a piece of shim material (an old feeler gauge set works great for swimming) and replacing the trip and pin. When the hammer drops at the corresponding time the bolt completely closes it is ready to go.

Early in the testing, we realized the tolerance variation in some hammers also created a problem where the guns would not cock the hammer far enough to catch it under the auto sear. This would cause the stick to follow the carrier back into battery without firing it. Some of the hammer spurs were much thicker and longer than others.

The cause of the problem was the lower power of the .22LR ammo was sending the much lighter bolt carrier back much slower than a standard 5.56mm carrier & not getting the hammer to fall back far enough. The understanding this is not usually a problem with the 5.56mm round is that the mass of the carrier and the speed it is recoiling at is much higher than that of the LM-7. Lowering the internals of the entire LM-7 system so the hammer would drop much lower and not rely on speed, but the only movement solved this issue.

Loading Belts

If there is any downfall to shooting belt-fed firearms, it is a simple fact that we have to load belts before we can shoot them. Lakeside Machine has helped us out a little in this area with the introduction of their new belt-loading device. A box of ammo, or the small some if you have bulk ammo, is dumped into the sorting hopper. A several shakes of the wrist and several are all lined up pointing from a small slot in the bottom of the device. A transfer bar is pushed up through the slot, catching the already lined up ammo, and slid out the front of the hopper. The transfer bar is then inserted into a loading block, and the result is ten rounds, all perfectly spaced and ready to be belted. When the belt is pushed over the series in the loading block, they are all perfectly spaced and seated to the correct depth when the belt is removed.

Several loading blocks can even be connected in unison to speed up the process. The author uses three blocks mounted together and has found that to be fast and comfortable. Since new belts are stable the first time they are loaded, there is a spike that acts as a belt spreader included with the loading tool that can be mounted with the loading blocks. A pure pass through each pocket before loading each first round, & it is no longer a struggle. No more blistered fingers from stuffing new belts & more time shooting instead of loading. As earlier mentioned, you can also use disintegrating links instead of the cloth belts. These are much easier to load but don’t tend to hold the linked ammo quite as secure as the cloth belts do. Some people have seen that given a slight pinch while loading them creates a little tighter hold. Both straps and links provide excellent results at the range. The 8-piece belt loading system is available for $40 and should be mandatory equipment for anyone who owns one of the Tippmann miniatures, a Vindicator Carbine or an LM-7.

ATF Technology Branch Ruling

Unlike many other production projects, there was still something necessary even when the bulk of the in-house troubleshooting had been made. The Technology Branch of the Bureau of Alcohol, Tobacco Firearms and Explosives makes legal determinations on new firearms and related accessories based on samples submitted. They examined these new designs and based on the item provided they will issue a decision in writing. There have been other plans submitted for determination changing the caliber & feed mechanism of specific firearms, where the devices were ruled fire-arms of themselves.

There have been different designs where Technology Branch has determined the new equipment was too readily convertible to fully automatic fire and ordered to be a machine gun conversion device. For new legal reasons a sample LM-7 was submitted to ATF and on December 6, 2005, it was determined that the LM-7 does NOT meet the definition of a firearm, a machine gun or a machine gun conversion device, and is merely an upper receiver, like many other replacement top receivers on the market.

Range Performance

Most of the range time was through sub-freezing temperatures at our production office in Maine. The LM-7 ran flawlessly in a semiautomatic mode right from the box. To achieve noise generation in full automatic, it had to be timed. This can be accomplished in shorter than an hour with the right materials and depending on the firearm you have; it may not involve any modifications at all.

As explained above, during preliminary testing we identified several variables in most more in-depth receiver fire control groups that had to be tweaked, and at this point, Lakeside Ma-chine has already addressed them in their new production models. Once we had everything set and timed, it ran excellent. We successfully ran some long belts just for function testing (ok, & a little fun) & fired several strings collecting data on muzzle velocity & rate of fire with several types of ammo in various configurations. The data from those tests are presented in the accompanying charts.

With this design. As an accessory for a military-style firearm that has been the USA primary service weapon for over 40 years, there are a lot of army guns out there as potential buyers. It is a reasonably valued way for a shooter to “upgrade” to a belt-fed firearm, and it is an excellent way to shoot on a statement with the low price of most .22LR ammunition. It is fun to shoot & works excellent right out of the box in semiautomatic mode &, with a minimal amount of timing & fine-tuning, in full automatic.

The conversion to LM-7 from a laboratory upper receiver is simple and can be completed in less than a minute. The vast number of accessories available for the LM-7, both from Lakeside Machine and current ones already on the market create an infinite number of arrangements to suit any shooter. Where the LM-7 acts in conjunction with previously owned, registered M16s & drop-in auto sears, it is about as close to having a “new” machine gun as we can get since May 19, 1986. There will always be room in this writer’s reference collection for an LM-7.

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