Okay... This is a long story, but I should start from the beginning.

I have an original Arsenal Bulgaria, milled AK receiver that I purchased over a decade ago, and sent off with a parts kit to Gary "INFORMER" Gucciano to be assembled. (Those of you who have been here long enough remember the "Informer" fiasco).
Anyway... Years later... After the Atty. General sorted through the Gucciano debacle, I got my receiver back (and some of my parts).
The only thing that had been done to it was the following:

1) The barrel had been put on a lathe, and turned down to accept the later Bulgarian "AK74" style gas block... (But it was turned down too small, and off center).

2) The rear sight block had been pressed onto the barrel, but not pinned.

3) The barrel had been pressed into the receiver, (and APPEARED to be un-pinned).

4) The whole assembly had been bead blasted, and covered with a nice thin coat of surface rust.

So... This assembly had been sitting on a shelf in my closet for 10 years, and I finally decided to do a proper Milled AK build on it.

First step was to press out the screwed up barrel.
After spending about a week figuring out how I was going to press the barrel out of an intact receiver (as opposed to just a stub), I finally came up with a setup that would work for my press, and was ready to go.

I started pressing... and this SOB was NOT moving.
After closer inspection, I was dismayed to find that It DOES have a damned barrel pin, but it was very well hidden by the sand blasting job that was done on the assembly.

Here is the problem:  The barrel appears to be pinned with a BLIND PIN???  It goes in on the right side, but does not come out on the left side.

How do I go about getting THAT out?

I'd take it to a machine shop, and have them drill/mill the pin out.

I'd also recommend using a milling machine to drill the pin out.
This is far more accurate than any drill press.
A good operator can machine a pin until there's nothing left but a thin tube that can be crumpled up and pulled out with tweezers.

Before doing so, make sure the the other side of the pin isn't hidden by rust or polishing/grinding marks.  Sometimes pins can be hard to see.

 

Yea, I immediately sanded, and polished that spot on the left side of the reciever when I noticed the pin on the right side.
Then I soaked it with penetrating oil to see if that would make a pin show up... nothing.
Maybe I will try the cold blue method you speak of, just to be sure....

Have you ever hear of an AK barrel being blind pinned?
I am wondering if he was trying to give it the look of a threaded reciever by hiding the pins.

I would pound on the pin to see if it pops out on the other side, just in case it is really well hidden.  Since nobody has ever heard of a blind pinned barrel, I doubt it really is.

I've been thinking about this over the weekend.
Assuming this was a finished Bulgarian milled receiver with a pressed-in barrel, the Bulgarians drilled the pin hole all the way through.

Unless the receiver hole was welded shut, the pin hole has to go all the way through.
Why the receiver would have been ground or polished to make the pin hard to see on one side but not the other is a mystery.

This is one of those things that can give you a headache.  If you can't find a pin on the other side, and you can't press it out with w BIG shop press, before damaging the receiver, I'd see a good milling machine operator and have him mill a hole all the way through, removing the pin at the same time.
Emphasis on the words "good milling machine operator".

It was a brand new, virgin reciever... In the white, and un-drilled when I sent it out to be built. (along with a virgin parts kit).
I am going to see about getting it milled out.

I also have a saw cut, milled rec. Bulgarian kit that is missing the rear, and middle reciever sections.
(If things don't work out, I know where I will be getting the reciever sections I need to have a re-weld build done).

The "virgin" SLR-100 receivers (below) had a starter hole on the right side that didn't go all the way through that side and no hole on the left side.  I think it's certainly possible that he might have only drilled or milled on the right side and used a blind pin.

OP-  I think someone with the right tools can salvage it for you.

There's no excuse for sloppy work like that.
The intent was for the pin to pass all the way through to properly support the barrel and trunnion and prevent weird vibrations or shifting.

Hmm
I was/am so disgusted with that mess i stuck my barreled milled receiver in the rear of the safe and tried to forget it.
have to check and see if he did this on mine also

well I dug it out and he/someone did a great job with the barrel pin it does go all the way through but it was insanely hard to see it,100 lumens and a magnifying glass to barely make it out on the left hand side.hope yours is just hidden well also

Yours was done by "Informer", also?

I had informer build a milled receiver gun just like this.  My barrel pin went clear through.  I was lucky enough for him to use a disk grinder to trim the barrel pin.  The problem was he removed part of the receiver too.  The side now has a nice angle to it.

I have on some parts (not gun) is sand it down to the metal and then either heat it up or put it in the freezer and you might be able to see the parting lines....also he might only have drilled and pined 90 percent across so one side has to have an entrance the problems getting it back out.....I think the best method is to get it machined since lets say he did not drill the hole all the way tru the  receiver then you will still have to do that also, In order to save your receiver its worth the money to get it milled professionally...I have only built one Milled AK and all the ones I have shot all had the barrel pin all the way tru..

Yup the gooch did mine also,after 2+ years of BS and getting help from a lawyer I got most of my stuff back(no $$) and about 1/3rd of the work done but just getting the barreled rec/bolt carrier assy back allowed me to put it behind somewhat.
I wont say what I would like to have done