PUT Together a: last time (3/20 issue), Matthews acquired his parts and started assembling the barrel and receiver. This time he installs the barrel, top cover, trigger group and buttstock. PSL part 2.
A new rivet will have to be bought or made. While a screw and nut would work, it wouldn't look very original. I simply made a new tubular rivet from a common Grade 2 bolt on my lathe. Those without a lathe can easily make this part with an improvised poor man's lathe, a drill to spin the part and a file to shape it to size.
The hard part about installing this assembly is getting the extremely stiff spring in place while aligning and holding the rivet and lever. I spent a lot of time fumbling with these parts before I got them in place.
To ease the fitting process, don't install the spring during test fitting. The lever may need to be trimmed slightly to fit right, and there is no need to fight with the spring until it has to be installed.
When checking for correct lever engagement on the magazine tabs, be sure to test fit with several magazines, since PSL magazines can vary quite a bit.
The bolt carrier could now be installed and checked for smooth operation. Unfortunately, mine could not be inserted into the receiver. The relief cuts in the top rails that allow the carrier to drop into the receiver were not deep enough and had to be filed deeper till the carrier would drop into place.
Once this issue was taken care of, a new problem arose. The top rails themselves were spaced too close together to allow the bolt carrier to slide forward. The gap between the rails was about 1/32" narrower than the width of the rail grooves in the carrier.
Each rail had to be narrowed down evenly until there was adequate clearance for the carrier. I trimmed the rails to obtain about .015" running clearance. After the carrier was moving smoothly on the rails, I installed the bolt into the carrier and tried to install the unit in the receiver.
By then, I wasn't surprised it wouldn't fit. The relief notches for the bolt lugs on the top rails were not deep enough to allow the bolt to drop into the receiver. The bolt notches had to be deepened and lengthened. Once the notches were re-cut, things dropped into place with no further issues.
All this hand fitting and re-cutting parts would not have been unexpected on a self-bent frame flat or an "80% receiver". This receiver was not ready to go, even though it was already finished with hot bluing.
After all the work needed to fit the bolt assembly, the blued finish was pretty well gone. Perhaps 1 was erroneously expecting a ready-to-assemble receiver that was just like ones going down an assembly line. This receiver should have been advertised as "major fitting required."
I thought the major fitting required made this receiver overpriced. I have used other factory-made AK receivers that required only minor hand fitting to work. It looked no better than receivers I have made out in my garage with hand tools. It did, however function OK after all the work, and its crude workmanship was not out of line with some (but not all) of the rather sloppily made AK rifles I have seen coming out of Romania. The AK has never been known as a finely built and assembled rifle, they just have to work regardless of what they look like.
It was now time to install the barrel in the trunnion and set headspace. I used a hydraulic press and some self-made fixtures to install the barrel. Some people install barrels with improvised tools such as hammers, punches, threaded rods, long pipe clamps, etc.
While I used some of those methods before I got a press, a press is the best for accurate control and ease of installation. There is also less chance of damage verses beating things together with big hammers!
Besides the press and some push fixtures, you'll need a barrel vise and headspace gauges. These gauges are used to determine correct pressing depth, of the barrel, which will set headspace. I got mine from Brownells. You'll need a 7.62x54R "Go" gauge and the same caliber "No Go" gauge.
If your barrel was factory matched to the trunnion, as evidenced by matching serial numbers, you may not absolutely have to use gauges. It is, however, a good idea to check headspace after the barrel is re-installed to the original location to verify that there was not a headspace setting error at the factory.
My trunnion was not serial numbered, even though the kit was advertised as matching numbers. So I decided to set headspace just as if I was using mismatched parts.
To hold the barrel securely in place I fabricated an easy-to-make barrel vise. A 4x4x1-inch block of aluminum had a barrel-diameter hole drilled in the center. This block was then split in the middle.
Then I drilled 3/8" holes through the ends to install 3/8" Grade 5 bolts that will clamp the blocks tightly around the barrel. This barrel vise will be used to support the barrel on the press bedplates while the trunnion is slowly pressed onto the barrel shank.
Before attempting to install the barrel in the trunnion, be sure to remove all burrs in the trunnion hole and on the barrel shank. Also verify that your center trunnion rivet heads do not extend into the trunnion hole.
Lubricate the trunnion hole and barrel shank with a very light coating of heavy grease such as bearing grease. Insert the barrel into the trunnion by hand as far as it will go and align the rear sight base with the notch in the trunnion.
Be sure these parts stay aligned, as once the barrel goes very far into the trunnion it will be very difficult to rotate =kink NI if it is out of alignment. Support the barrel vise on the bed plates and begin pushing the trunnion onto the barrel shank with a push rod that is bearing against the trunnion. Brass or aluminum rods are the preferred tools for pushing on the trunnion.
Never press on the thin sheet-metal receiver; you run the risk of bending the receiver or shearing off the rivets. Press the barrel on about three-quarters of its full depth, then stop. Take a break from pressing and go get your headspace gauges and bolt.
Remove the firing pin and extractor from the bolt. These parts are held in with crosspins. Note that there is a right and wrong direction to push these pins out.
Since 7.62mm Russian rounds headspace on the rim, the gauges only have a short stub that enters the chamber rather than a cartridge-shaped portion as is common on rimless rounds. Install the "Go" gauge in the barrel's cleaned chamber. While holding the gauge tight against the barrel breech, install the bolt in the trunnion and rotate it to its fully closed or locked position. You should have a notice-able gap between the face of the bolt and the rear of the headspace gauge.
Now, slowly press the barrel in further until the bolt face just touches the rear of the head-space gauge when it is flush against the breech face. Do not overpress and cram the barrel and headspace gauge down tight against the bolt under tons of pressure, otherwise you may not be able to get the bolt open to remove the gauge.
Now remove the assembly from the press. Open the bolt and remove the gauge. You may have to use a small soft-faced punch pushing on the bolt lugs to open the bolt. Now insert the "No Go" gauge in the chamber and re-install the bolt in the trunnion.
If you have set the headspace correctly with the "Go" gauge, you should not be able to rotate the bolt into the fully closed position with the "No Go" gauge in the chamber. This will indicate you have set headspace correctly.
Basically the "Go" gauge sets minimum headspace with the bolt closed and the fact that the bolt will not close on the "No Go" gauge indicates that there is not too much headspace. If your bolt will fully close on the "No Go" gauge, it indicates you have not installed the band to its correct depth and you need to check your procedures.
If and only if your headspace is right, you can go on to installing the barrel crosspin. The crosspin will lock the barrel and trunnion into this position permanently. On my project, it turned out the trunnion was the correct trunnion and the crosspin holes in the barrel and trunnion lined up exactly. If your holes line up exactly, your crosspin can now be installed.
When I say lined up exactly, I mean right down to the last one thousandth of an inch. Any misalignment is too much! If the holes are not perfectly aligned and you drive in the crosspin, all it will do is push the parts out of correct alignment. If your holes do not align. you will have to precision ream the hole to a slightly larger size and install an oversized crosspin.
You can use fractional or metric sized hardened precision dowel pins for crosspins. In a pinch you can also use the shanks of high quality M2 steel drill bits for pin material. Never use soft steel or other soft metals for barrel pins. The pins must be strong enough to hold the trunnion and barrel together under great force, since the pin and press fit are the only things holding the gun together. The pins must also be a tight press fit so they do not work out under use.
At this point, most of the hard work is done. All that remains is to fit some of the remaining parts to the barreled receiver.
The next part I fit was the top cover. Since it was going on a new receiver, some minor hand fitting was required to get it to fit correctly
I then chose to fit the buttstock to the rear of' the receiver. The wood that extended into the receiver needed to he trimmed slightly to allow the stock to seat fully. On the PSt, the stock is held in place with one wood screw through the tang and one long screw up through the bottom of the grip on the thumbhole stock.
The nut for the long screw is not inserted into the receiver as it is on a standard AK format gun. On the PSL, the nut is housed in a small depression cut into the top of the stock. The screw just extends up through the stock and receiver to the nut and when tightened, it draws the parts together.
When I installed my fitted stock, I could not get my screw to go through the grip to reach the nut in the stock. Examination revealed that the maker in Romania didn't see fit to drill the necessary hole in the receiver to allow the screw to pass through the rear of the receiver. I guess they figured why should they drill the hole if they could get me to do it for them? The hole was not a precision located hole that needed to be hand fitted at assembly; this was just another example of poor workmanship.
Next came fitting the front handguards. On my PSL kit the front upper handguard was removed from the gas tube. All that is needed to install it is to rotate it around the tube between the retainers. The reassembled gas tube assembly fit the.gun with no fitting required. The lower handguard did need some minor fitting, but nothing that was out of the ordinary.
Now it was time to install the fire control group (trigger, hammer, and disconnector). Since I wanted my PSL project to be U.S. complaint, I replaced the factory fire control group with a U.S.-made TAPCO G2 double hook unit that I obtained from Brownell& The TAPCO unit would count as three U.S.-made parts.
The rectangular cutout in the bottom of the new receiver would not accept the new TAPCO trigger or even the original trigger. The cutout had to be opened up some with a file to allow for adequate clearance.
Since the original PSL trigger was a single hook style, I also had to cut an extra relief for the double hook TAPCO unit. Fortunately there were no other problems fitting the new fire control group. Rather than using the notorious "Shepherd's hook" hammer and trigger pin retainer, I used small spring clip pin retainers that are available from hardware stores.
I installed the bolt and carrier and checked for proper fire control group operation. Hammer, trigger and disconnector function were fine. Since this project was basically a scaled-up AK-47 firing the vastly more powerful 7.62x54R cartridge, I installed a Buffer Technologies recoil buffer. This would help cushion the impact between the trunnion and bolt carrier as the carrier reached its full rearward stroke.
I now turned my attention to the muzzle. I replaced the original imported PSL muzzle brake with a U.S.-made flash suppressor. I obtained a Liberty Suppressors Phoenix AK-47 unit from Brownells. This suppressor featured spiral grooves and a wide opening at the front.
The PSL barrel is threaded 14mmx1 on the muzzle just as a standard AK barrel, so any AK muzzle attachment will fit. Be aware, however, that some cheap no-name muzzle brakes and flash suppressors fit pretty sloppily.
If you use a style that only has a small exit hole on the front rather than an open design, you must verify.that it fits snug enough that the small hole allows the bullet to pass through without striking the sides, which will really ruin accuracy.
With the U.S. flash suppressor and trigger group, I still needed one more U.S.-made part to meet the parts count. While there are many options for U.S parts, I wanted one that was inexpensive. To meet my "cheap" requirement, I decided to make my own U.S. compliance parts in the form of U.S.-made magazine floorplates.
I fabricated four self-made, and therefore U.S.-made, floorplates from .035" thick 4130 sheet stock that I. obtained from Aircraft Spruce Co. for less than $5. I took one of my original imported floorplates and unfolded it to create a pattern or blank to make new ones.
I laid this blank out on my sheet stock and traced around the edges. I then cut these blanks out with a band-saw. For those without a bandsaw, the parts can be cut with a hacksaw or tin snips. I placed the old magazine over the cut blanks and traced the outline of the magazine base onto the blanks. This would be my bend line for forming the sides of the floorplates.
I placed the blanks in a vise and bent the edges over with a hammer to 90[degrees] at the bend lines. I then cut out a mandrel sized like the flanges on the base of a magazine out of some more sheet stock. This mandrel was then placed between the 90 sides of the partially formed floorplate and the remainder was bent over the mandrel to duplicate the interlocking lip of an original doorplate.
The small square hole was cut in the floorplate and the tab on the end was trimmed to size. Once test fitting indicated a well fitted floorplate, 1 stamped the parts with "USA" to identify them as U.S. parts. About two hours worth of work and less than $5 worth of steel resulted in four inexpensive (purchased floorplates are more than $15 each!) U.S.-made parts. Remember you don't have to buy your parts from someone and pay big bucks if you just take the initiative and make them yourself.
Next month (5120 issue): Matthews finishes the PSL
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|Date:||Apr 20, 2012|
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