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Discussion Starter #1
Tortort Manufacturing is now selling 5.45x39 / 5.56x45 milled side folder receivers.
Tortort milled sidefolder receiver.JPG
https://tortort.com/collections/tortort-100-milled-ak-receivers/products/100-complete-milled-sf

I'd like to build a 5.56x45 milled side folder SBR. I have the following Bulgarian 5.56x45 barrel assembly that I understand was originally made for a milled receiver.
Milled 556 SBR barrel assembly right view.jpg
Milled 556 SBR barrel assembly left view.jpg

So assuming the barrel will press fit, it should work perfectly. However, I don't know what bolt, carrier and magazines it would use. Does anyone have an idea? I don't want to shell out $500 for a receiver only to find that I can't find a bolt and carrier that's compatible. Any idea which magazines this receiver would take in 5.56x45? I pretty much have them all, but I'd like to know before purchasing.[SUB][SUP]
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The Tortort site notes the chamber journal is 22mm.
The barrel assembly you have is for a 23mm chamber journal.

You should contact Tortort about whether they set up the receiver for a short lug or long lug bolt.

Generally a 22mm Bulgarian/ Russian AK74 would be a long lug narrow stem bolt. Meaning an AK74 bolt and carrier in 5.45 could be used.

How they set up the receiver lugs and bullet guide channel can affect the bullet guide type and barrel setback.

Dunno the answer to the bolt type but your barrel assembly would need turned down to 22mm at the chamber end.

Tortort should have an answer.

In the other receiver types listed., they note as 5.56 specific set up.
 

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Discussion Starter #3
I sent an email and here's the reply that I received: "Our 5.45 and 5.56 are the same part. These have a 22mm barrel journal and can run the 74 or 5.56 bolt/carrier. The bullet guide hole is not drilled so they can be built with thin stem/long lug (74) or the large stem/short lug (5.56)". So turning the barrel down to 22mm is doable for someone who knows what they're doing and has the right tools?
 

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Yep., pretty much what I supposed but since they did not state it in their description it was worth asking about.

The barrel unit you have may be a pre-drilled gas port in the barrel.
If that is the Bulgarian milled pattern it may be set up for the short lug large stem bolt.

That is the other thing to check/ determine..

This affects the barrel setback into the receiver.
The Bulgarians went two directions in the 74 series vs 100 series rifles as far as bolts and carriers and barrel components.
 

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Discussion Starter #5
Thanks AKBlue for pointing that out about the gas port hole. I would have been very disappointed to order everything only to find out that it won't work. I've looked all over for a Bulgarian 5.56x45 bolt and carrier. K-Var has the carriers, but the bolts are nowhere to be found.

Am I correct in understanding that I could use an AK74 bolt and carrier, but I'd have to use a different barrel because of where the gas port hole is drilled on the barrel that I have?

As one last alternative, I'm wondering if a Yugo M85 bolt and carrier will work. I took some measurements and here's what I found:
Bulgarian 106 series 5.56x45 bolt: 3.338" length and 0.429" diameter stem
Yugo M85 5.56x45 bolt: 3.342" length with 0.342" diameter stem
Bulgarian AK74 5.45x39 bolt: 3.442" length with 0.346" diameter stem.
Bolt options.jpg
Bolt and carrier optoins.jpg
 

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The bolt length and diameter are most important for matching the proper bolt/carrier combo.
The bolt lug type is what determines the barrel setback and bullet guide type.

Some of those Bulgy barrel units had predrilled gas ports and some not.

The Yugo bolt should work.
It hasbeen a while since I did something kinda similar., so verify what I'm stating here.

I believe that barrel assembly you have was made for the short lug bolt head type.
This means the barrel sets back further in the receiver to accommodate the shorter lugs andc requires a bullet guide that has the turning guide (ramp) more rear set as on the milled Bulgy 100 series that barrel was made to fit.

Another way to check thenarrel is to measure the width of the RSB and compare it to an AK74.
If it is wider it is for the milled receiver type Bulgarian series.

Another option would be to use a custom gas tube and piston of the ling lug bolt is used.

Hope this makes sense.
 

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Discussion Starter #7
Some of those Bulgy barrel units had predrilled gas ports and some not.
I looked and the gas port hole is there. Oddly, it's rotated to about 1:00. Fortunately, they didn't pin the barrel components. It makes me wonder why they'd even bother to press on the components if they were not going to bother doing it right.

Another way to check thenarrel is to measure the width of the RSB and compare it to an AK74.
If it is wider it is for the milled receiver type Bulgarian series.
The RSB is definitely the wider milled type. Back in the day I bought three of these Bulgarian 12.5" barrel assemblies, one in 7.62x39, one in 5.45x39 and one in 5.56x45. The 7.62x39 barrel assembly had a wider type RSB. When I built the rifle, I had to use an M92 front trunnion. The 5.45x39 barrel assembly had a regular AK74 RSB. I used it to build a 104CR type rifle. Finally, there's this 5.56x45 barrel assembly with the wider RSB. Everything would be perfect if I could just find a Bulgarian 5.56x45 bolt. Seems odd that K-Var can't keep basic parts like this in stock.
 

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I believe the Zastava M85 bolt and carrier will work.
But those are not common either.
I put two of the Bulgarian 5.56 barrels on a Zastava M85 pistol-to-rifle conversion several years ago.

One on a M85NP with a M76 gas tube and gas piston >>>







The other on a M85 kit build conversion to a rifle with conventional barrel components and a relocated PAP rail>>>




 

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Discussion Starter #9
I believe the Zastava M85 bolt and carrier will work.
But those are not common either.
No they're not. I have a couple of virgin M85 kits. I have a receiver for one and am going to build it as soon as my Form 1 is approved. I could take the bolt & carrier from the other kit and part the rest of it out.
 

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The Virgin M85 kits have the convex center ring circle on the bolt face.
Not the end of the world but not ideal.
 

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Discussion Starter #11
Would you please elaborate as to why that’s an issue? Is it a problem with this particular build or just in general?
 

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I believe the Zastava M85 bolt and carrier will work.
But those are not common either.
No they're not. I have a couple of virgin M85 kits. I have a receiver for one and am going to build it as soon as my Form 1 is approved. I could take the bolt & carrier from the other kit and part the rest of it out.
I’ve got one of the fixed stock receivers, building a Sam 5 clone. I’ve got all the Bulgarian stuff I’m using on mine, but if you can’t find a bulgy bolt why not try a Galil bolt? That’ll fit in the Bulgarian carrier i believe
 

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Would you please elaborate as to why that’s an issue? Is it a problem with this particular build or just in general?
Just in general., the ring in the bolt face indents the brass cases and makes reloading them pretty much useless for reuse.

Functionally it does not affect the firearm., but milling off the ring may require adjusting the extractor pawl.
 

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Discussion Starter #14
I’ve got all the Bulgarian stuff I’m using on mine, but if you can’t find a bulgy bolt why not try a Galil bolt? That’ll fit in the Bulgarian carrier i believe
I just tried it and it does fit. The bolts look identical except that the Galil bolt appears more finely produced. I put the Galil bolt in my 106CR, but it stopped short of going all the way forward for some reason. At any rate, good idea. Looks like I have a third option now. Any idea who sells new (or newish) Galil bolts?
 

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I’ve got all the Bulgarian stuff I’m using on mine, but if you can’t find a bulgy bolt why not try a Galil bolt? That’ll fit in the Bulgarian carrier i believe
I just tried it and it does fit. The bolts look identical except that the Galil bolt appears more finely produced. I put the Galil bolt in my 106CR, but it stopped short of going all the way forward for some reason. At any rate, good idea. Looks like I have a third option now. Any idea who sells new (or newish) Galil bolts?
Nope, you’d have to keep an eye out for someone parting out one of the kits imported a couple years ago, those were in good shape. I sold off my spares, but I remember them being pretty darn similar. If you’re looking to use a Galil bullet guide it’ll need to be modified, the feed ramp in the front blocks the bottom of the bolt and prevents it from going into battery when placed in one of these receivers. I’d like to find a bulgy 5.56 guide but I feel like that’s gonna be tough. That’s the only part I lack for this build...well aside from the time to get around to completing it lol
 

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Discussion Starter #17
$155! Ouch. They're selling the ARM parts kits for $330 (with damaged handguards). I wonder if the ARM carrier would work. BTW, I received notice yesterday that my milled receiver has shipped.
 

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The bolt carrier should work just fine though you might need to change the piston. I'm sure you could sell the parts you dont use for a decent amount.
 

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Discussion Starter #19
I be you're right.

I have another idea. What about using a hinge block instead of the RSB that came with the barrel assembly along with a top cover that has a peep sight?
milled hinge block.jpg
sighted top cover.jpg
The top cover indicates that it's for a krink. Will it only work with a krink or does it just require the hinge block?

https://www.k-var.com/hinge-block-for-762x39-and-556x45-calibers-for-krinkov-arsenal-bulgaria
https://www.k-var.com/bulgarian-krinkov-new-generation-top-cover-fits-all-krinkovs-with-flip-up-peep-sight
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