Happened to me on several G builds, the fix is easy. First get a big ass slot screwdriver, turn the rifle upside down on your workbench, put the blade of the screwdriver under the mag catch (where the back tab for the magazine would go) and lift up on the screwdriver- you are actually trying to pry the mag catch up and away from the bottom of the receiver making a bit more clearance for the magazine tab, put some good pressure on it. Now try the mag, it should go in a little more if not all the way. If not give it another go but press harder. If this fails to work get a dremel and a thin diamond bit and whittle away at the mag catch engaging surface until the magazine locks in nice and tight.

You should always rivet the trigger guard in place 1st before riveting the trunnion in place.
Rivet trigger guard, slide front trunnion in receiver and test fit mags. Mark the receiver then drill rivet holes.

You can tweak the mag catch if it's close but taking material off various surfaces changes the feed angle, case head contact with the bolt on feeding, etc.

Both these responses are . . . .

Hmm, how to put this tactfully?  . . .   a procedure with which I have little experience or interest.

How about - "ignore those two posts"

They are totally wrong in every regard - very bad advise.

Always install the front and rear trunion before the trigger guard.  The front trunion has ZERO to do with magazine fit (well, except when converting a SAIGA to take standard mags . . .).  All magazine fit is always done with the selector stop plate (SSP).  That's why it is an "adjustable" part, and the others are not.

If, without the trigger guard in place, the mag doesn't fit, then the opening to the mag well is undersize.  On old US receivers built off the NDS-3 template, the mag well is 1mm short. It is a lot easier to open the mag well before installing the trigger guard.

The selector stop plate adjusts for mag height, by its thickness; and  for front-to-back mag fit, by the tab on the front edge.

On a 5.45, the mag should bottom out on the rails. reduce thickness of SSP until it does. The clearance cut on the mag feedlip for the ejector indicates it needs to insert that far.

On a 7.62, you want the mag to bottom out on the rails, or as close to doing so as possible without completely removing the center of the SSP.

The center cut on the SSP is at an angle of 4-5 degrees.

If both of these are good and mag still binds with mag catch depressed, check center support.

On many new ((10)), they will kiss the center support. This is one place where it is ok to take a couple file strokes on the back of the mag, or just slam it in a few times and the plastic will scrape.

On a 5.45 or if there is solid contact with the center support, cut a flat on the front of the center support to clear the top rear of the mag.

ONLY AFTER ALL THIS

insert mag with mag catch at rest. If it doesn't latch, file the top of the mag catch, maintain the 98 degree angle.

If it does latch, press the mag up and pencil a line on the side of the mag at mag well
Pull mag down and pencil a line on the side
measure distance between two lines. If > 0.5mm, the mag catch is too short. Weld up and refit. This is less critical on the large base 7.62 than small base 5.45 and 5.56.

The mag catch should protrude forward of the leading edge of the SSP by 0.5- 1.5mm.

If, upon grasping the mag and pulling to the rear (while thumbing the catch) the mag catch locks up, AND by thumbing the mag catch w/o touching the mag, the mag drops free, your front to rear is too long.  Remove the SSP and weld up the leading edge until the mag doesn't fit.  Then file it back until it just clears.

You can test-fit the plate initially by affixing it with smallbolts and nuts. After verifying everything, then rivet.  After a few builds, you can just hold the plate in place while testing mag clearance.  Even after a thousand builds, I sometimes need some final fitting after riveting, but it is rare.  

So the magazine lip and body do not make contact with the front trunnion?
The hell you say, LOL!

sure - the magazine contacts the front trunion.

the front trunion is the ZERO point.

The front trunion  should be flush with the front of the receiver, riveted, and then you have your start point.

The SSP, rear of mag well (rarely), and mag catch are the adjustable points.

Front trunion and trigger guard are both supposed to be fixed locations.  But subtle variances in the stampings and stackign of tolerances, can cause mag fit problems.  So . . . . MK decided to make a part that WAS adjustable.  The SSP.  

It makes total sense, once you think about it.    

I rivet the trunnions 1st. With a magazine in place I mark where the trigger guard needs to be riveted in for a good fit. Very simple.

Simple, but still wrong.

Why is it so difficult to understand?

The trunions and trigger guard are fixed locations.

The selector stop plate does front-to-rear and vertical adjustment.  Then the mag catch is fitted to the magazine.

Do you think I just pulled the dimensions I gave above, out of my ass?   I haven't built over a thousand AKs by guessing.
I pulled the specs out of Russian, East German, and other arsenal repair manuals.

I follow the directions of the guy who designed it, and the engineers who established the production specifications.   And I use the gauges they prescribe, to check it (both original and reproductions).  I suspect that their 60+ years experience in producing the rifle, is more credible than whatever silly ways ya'll come up with.

But, but..... that is the proper way to do it. Here in 'Merica, most just wing it, with the expected results

No, it's not wrong. There is plenty of play in the trigger guard to move it forward and snug up the mag. The mag catch is another adjustment that might have to be made. Every AK I have built has required some movement of the trigger guard. There is nothing precise about an AK. You might want to look up your ass again or try it. Chill out

Yes, you are totally and completely, 100% wrong. I am totally and completely right (get used to it).

You know why I'm right and you're wrong?  Because "right" is defined by the guy who designed the freaking gun, and I copy him.

The blueprint clearly calls out the location of the trigger guard rivet holes - a fixed location.  It is not "moved forward to snug."  Print series 3-24344   (apparently this website won't accept the Russian text, but it translates as    6P1  housing (receiver)"   and "6P1 box (receiver) assembly characteristics".

You can do whatever the heck you want with your gun.  But you're still wrong.  In fact, the way by which you came to the wrong conclusions demonstrates a poor understanding of the system.  As I said before, it's not complicated.  Up, down, forward & back - all designed into one little stamped part.

No, silly child, I am not going to post thousands of of images for you.

I'm sorry you're too lazy to do your own research.  

I'm sorry you lack the wisdom to understand that the guy who designed the gun establishes what is correct, not you.

And I'm sorry you were brought up in an age where foolish people fluffed your self esteem, and led you to believe that your opinion was an equally viable alternative, to facts.  2+2=4.  Temper tantrums will not make it equal 5.  It is always 4.    I am not close-minded to stick with 4, and to entertain no "other opinions".

There is only one right way.  The way the guy who designed it says . . . .


Hopefully, others who view this thread will have the capacity to learn. I've been studying this stuff for 30 years and I'm trying to give away so much of my knowledge, so that it won't be lost.  When I started, I had to communicate by mail, and use libraries, and buy books.  Now it's all a few clicks away on your computer, but this incredible gift comes to a generation on which the knowledge is lost - because their fluffed self-esteem blinds them to the real world and they haven't the discipline or inclination to learn anything not spoon-fed.

I've tried to educate you, but you seem uninterested.
Heck, I even publish an extensive book and video set on AK gunsmithing (as well as FAL, HK, BHP, SIG, etc.)  Those I do charge for, but I've got to eat . . . .
((sigh)).  So much for casting pearls.

As for you - here's a fish slap.  Scaled down about 20x and cropped.  I'll be awaiting your apology.

Posting illegible prints or drawings really does not address OP's  issue of an assembly / fitting problem.
(It has jack shit to do with fitting and assembly as does the "silly child" comment)

Lets play stack that tolerance....
Since the front of the receiver is the datum point:

Receiver OAL:                        259.0 mm  +/-  .2mm
Trunnion holes in receiver :                     +/-  .1mm

.3mm /  .0118"  if the above are "in spec" and not including any tolerance in the trigger guard rivet holes or the actual trunnion itself so it shows how much the parts can move around the tolerance zone if made to print.
Since I have never had two trunnions in my hand that were identical or receivers ( including the ones I made myself from scratch)  it just shows the importance of fitting finished parts.

Its pretty simple to bolt the trigger guard and selector stop in place , slide the front trunnion in the receiver and test fit some mags before riveting anything and adjusting what it take to make it work correctly.
Its not the way MK did it but some things have changed in the last several decades and there is more ways then one to obtain the end result/s.









Legible redraw prints and credit to whomever did it.

I explained to the OP, in my first post, how to address his problems.

Everything else has been to explain why the other answers are totally and completely wrong.  Moving the trunion and/or trigger guard, to adjust magazine fit, is not an equally viable alternative, it is wrong.
Right  is installing the parts where the blueprint says to, and adjusting the selector stop plate for fit - as that part was designed to do.  The print section only shows the trigger guard location is fixed.  It is not "fitted."




If the front of the receiver were the datum point, then why would you be adjusting it?    A datum point is the fixed location from which other dimensions are determined.  You prove in your own explanation, why you are totally and completely wrong.



The way to achieve the desired results, is to use the part MK designed to be adjustable, as a point of adjustment.  Not to alter fixed locations to work around your own willful ignorance and ego.   That you can still get a gun to work, doing it your own totally wrong way, is a credit to the design, not a validation of your foolishness.

I've explained the "correct way" and demonstrated why it is the correct way.   When people with vastly more knowledge and experience than I, show me that the way I was doing it was wrong (and why), I enthusiastically change to the right way.  While you are free to continue clinging to your wrong way, I'm not seeing any upside to it.  That's what a silly child does.  

thank you for posting.  despite all the drama, i really just want to know the right way to do things no matter how i get the info.