Gunsmithing MAK 90 Rifles
The most common AK rifle copy sold in the United States is the Chinese-made MAK 90. Designed as a military weapon, it is easily disassembled and worked but not necessarily simple.
While the Russian and other military AK type rifles have battlefield exchangeable parts, the MAK 90 does not. Some MAK 90 parts will exchange but because the rifle was made strictly for sale to the U.S. public, not for battle, each was fitted to function individually. While some parts may exchange, the key to working this rifle is recognizing that not all parts will. It gets a little complicated from there. We cant tell you which parts will exchange until you get into specific manufactured lots. Many intentional changes, from different springs to varied dimensions of internal parts, were made in the different plants that produced these rifles. When you work on a MAK 90, keep this in mind if you are trying to replace or change parts.
Lets take three MAK 90s and an SA 85M apart to look at some of the problems you might run into and a few improvements that you can make. As the stamped receiver is the most common, we will use one as our classroom. When you are working on machined steel receivers, you will find slight variations from the stamped receivers. This is also true of the Hungarian AKM, SA 85M, the Chinese 56-S or one of the many Sino-Sovet AK/AKS rifles.
As we disassemble the rifle, there are several factors to look for that will make a great deal of difference as we go along. A rifle that has had a thousand rounds fired through it is much easier to work on than a nearly new rifle. Poorly fitting parts can be found in the new rifle, but only time and use will show wear points, spring problems, and slippage.
Remove the magazine, check the chamber and dry fire the rifle. Wiggle both the front and rear of the receiver cover to make sure there is no excessive movement. It should be tight both front and rear. The rear of the guide rod sticks through the rear of the receiver cover. Push the guide rod into the receiver cover and hold it there while you pull up on the rear of the receiver cover. When it comes loose at the rear, lift it up and pull it back out of the receiver to remove it. With the receiver cover off, you can push the recoil guide and guide spring forward until it clears the guide bars in the receiver. Now it may be lifted up and pulled straight back for removal. With the safety on fire, pull the bolt back as far as it will go and lift it up and out of the receiver. If your receiver cover was loose, place it back on the receiver without the internal parts inside and try wiggling it again. If the front is moving from side to side, then squeeze the front bottom edges of the cover together. This metal bends easily, so be careful. The same procedure will work on the rear of the receiver. If the front lip allows the front of the receiver cover to move up and down, take a pair of needle-nose pliers and flatten out the top curve on the lip of the receiver cover. Remember, a little bit of pressure goes a long way. You may need to try it several times to get it just right.
To remove the bolt from the bolt carrier, push the bolt to its rear position in the carrier and rotate it clockwise a quarter-turn. Now push the bolt forward and out of its hole in the carrier. All three MAK 90 bolts are well finished and properly hardened but the bolt from the machined receiver is much better.
The bolt from the Hungarian SA 85M is slotted down both sides and appears to be perfect in every way. Inspect your MAK 90 bolt for rough edges and burrs left from machining. Both our stamped receiver models needed their rough edges buffed. Work only the rough edges; do not try to polish the whole bolt. If you want to improve its looks, use a soft wheel and jewelers rogue because hard wheels and medium buffing compounds remove too much metal. The SA 85M bolt is blued, but doesnt need polishing at any rate. The fact that these bolts are serial numbered is very important because they are not always interchangeable. None of our four bolts miked out to the same size.
AK-type extractors are very tough and rarely break. Just to see how easily they interchange, we miked all four extractors and found that only the two from the stamped receiver rifles would swap. The pin that holds the extractor in place is often hard to drive out. If you are having problems getting it out, it may be better to allow the bolt to sit overnight in penetrating oil. These Chinese guns are not constructed of the best metal in the world and you can damage the bolt body by trying to drive out a stuck extractor retaining pin. In battlefield conditions, the most common extractor problem was getting so much dirt between the extractor and the bolt body that the extractor could not move enough to grip the cartridge rim.
Like the bolt, both bolt carriers on the two stamped receiver MAK 90s had sharp edges and one was very rough inside the hole through which the bolt moves. Proper, but careful, polishing of these bolt carriers helped both of these rifles but really made a difference on the one that was the roughest. While the firing pin seems small and weak for a military rifle, it holds up as well as any, and better than most. Many owners of these rifles want a replacement firing pin so make sure the replacement is exactly like the original. The firing pins fit very loose inside the bolt on the Chinese models is necessary because these are self-cleaning. This design and space allows residue to work out the back of the bolt upon firing. Do not attempt to make a tight-fitting firing pin. The SA 85M, however, has a tight-fitting firing pin that is sealed against dirt and residue and self-cleans around the bolt itself. Slot areas of this bolt carrier can be smoothed with extra fine emery cloth.
The piston should have some slight movement in its joint with the bolt carrier. Any attempt to drive out the retaining pin holding the piston into the carrier should be avoided on the Chinese models. If it is absolutely necessary to replace the piston, drill out the retaining pin rather than break the carrier. Clean the piston but do not try polishing it. Only the surface is hardened and it will wear fast if this surface is scratched or removed. The SA 85M was perfect from the factory.
The recoil guide assembly varied a great deal on all four guns I examined. The SA 85M guide is made differently than what you find on the Chinese guns. It appears to be machined steel with a triangle shaped lug on each side of the release button. These help guide every thing into place and hold all parts steady after they are assembled. The spring guides are two U shaped steel rods and are locked together on the front end with a machined steel, clip type recoil spring cam. The Chinese guide rod assembly has a cast steel rear piece and a steel band for the rear half of the spring guide. The front half is a piece of twisted spring steel wire reaching to the front end of the recoil spring where it is bent around a small metal plate retainer. The edges of these cast rear pieces are rough and sharp but serve no function other than take down so it is not necessary to do anything to them. They can be improved for looks but part will have to be re-blued if you remove the sharp and rough edges. One good fact here is that this cast metal will accept a good cold blueing using 44-40 cold blue. Make sure this bent wire grips its end retainer plate tightly. Even though the tension is removed while firing, it is possible for this part to jam the action of the recoil spring if it comes loose inside the rifle. This can also damage the spring guide, spring and carrier.
The handguard, which houses the gas tube assembly, is removed by rotating the gas tube latch lever up and pulling up on the back of the handguard in the same manner you would on an SKS. The big difference here is that the SKS gas piston stays inside the gas tube while the AK type is locked onto the carrier. Removing and cleaning the gas tube assembly on the AK is easier than the SKS. It is easy to forget, but always clean the gas ports every time the gas tube is removed.
Remove the safety lever from the rifles by moving the safety up into the safe position, then pushing until it is pointed straight up. This will release it so it can be removed out the side. Unless someone attempts to modify this safety or replace it with the selective safety from a full auto AK, they do not break.
Installing a full auto AK47 safety lever in any semiautomatic rifle is strictly forbidden; ATF doesnt care if the rifle will fire full auto or not. Any part from a full auto AK47 installed in semiautomatic AK type rifles is illegal, period. Modifications deemed by ATF as an attempt to make a weapon fire full auto will get you serious jail time.
As we talk about the trigger assembly, please keep that in mind. All these semi-auto AK type rifles have similar triggers but vary from point to point. For example, the SA 85M has only one release sear on the left side of the hammer while the Chinese MAK 90 has two, one on each side of the hammer. The long military trigger pull of all AK type rifles is what most sport shooters want to get away from. While the single sear release of the SA 85M is much smoother than the other rifles, it is still just as long.
The trigger and hammer are both held in place by their respective pins, which are in turn secured by a retaining spring. Relieving the spring pressure will release these two pins and allow the removal of the firing system. Even the SA 85M trigger release was greatly improved by polishing all bearing surfaces. Do not attempt changing the springs or spring tension; its another ATF no no. Polishing and smoothing all the sears bearing surfaces greatly improves the smoothness of the Chinese rifles. Solving the long trigger pull is not hard and can be done several ways but every one of them can be construed by ATF as an attempt to illegally modify the firearm. Written permission to shorten the sear and add a set screw under the trigger to shorten the travel is not easy to get. Using a small file to get rid of the sharp edges on all these sear surfaces will work wonders without worrying about jail time.
While we are talking about the wrath of ATF rules and regulations be very careful in what you add to a MAK 90. If you take a thumb hole stock off and add a straight stock and pistol grip or you saw out the wood between the stock and pistol grip, you may have broken the law.
Feeding problems are nearly always caused by a magazine that does not fit correctly, a dirty rifle, or bad ammo. If the rifle works well with the magazine that it came with, blame the replacement magazine if the rifle doesnt function correctly. Some of the new AK-type rifles come with the inside the of magazine well spot welded so it can not accept a high-capacity magazine. Grinding this weld off the rifle is illegal as it changes the rifle from what it was as imported. High capacity magazines will not fit into these rifles because the spot of weld keeps the rear locking lug of the magazine from entering the rifle. The low capacity magazine that it comes with has the same lug but they cut out a small amount of metal from the center of the lug to allow it to pass into the well. I have never heard anyone say it is illegal to cut into this rear lug on another magazine to make it match the small capacity magazine it came with. Either way, there are a lot of people doing it. The biggest problem with extra magazines is a large number bought at gun shows or through the mail just do not fit the rifles or wont feed rounds. As these are often reject magazines in the first place, it will probably be cheaper to buy a good one than try to fix the bad one. Nevertheless, let me give you a few tips on cheap magazines. Make sure they fit correctly going into and out of the rifle. The magazine must fit properly before it can feed properly. Most of the time, a small amount of filing in the areas that drag will take care of this. If the cartridges do not ride as high in a magazine that doesnt work as they do in one that does, try the following: File off the sharp edges that are holding the cartridges down. Check to make sure the edges have not been bent in and check to make sure the follower is going all the way to the top. Also examine the inside of the magazine body to be sure the internal welds are smooth.
You may get a rifle that has had the magazine latch filed off by someone who was trying to make the rifle fit a magazine as opposed to making the magazine fit the rifle. The magazine latch is held by brads and must be drilled out but the latch and latch pin are cheap and easy to get. These latches come a little long so you will have to fit it but this is better than their being too short. When you brad the end of this retainer pin over, remember that these Chinese pins are of soft metal, as is the latch housing. A hard blow can bend or break either part and you will be worse off than when you started.