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BHO Bolt Hold Open modification

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I ordered one of Mike's 20 round drums before I had a Saiga 12 in hand. After ordering the drum I bought the shotgun. This was before the Saiga supply dried up and you could still buy one for less than $400. So I've been tinkering with the gun and doing the pistol grip conversion slowly while waiting for the drum to arrive. Wouldn't you know it. The drum arrived two weeks ago so I had to get serious about finishing the conversion.


All went well until I tried to get the safety and the bolt hold open both installed. I could get either one in by itself but not both together. So I did multiple searches of the forum looking to capitalize on the experince of others. I found lots of posts describing the problem and a couple that talked about fixing it but none in great detail.


So, as my way of giving back to the forum for all the help it has given me in my several conversions, I will detail here my solution to the BHO / safety problem.


Here, obviously, is my modified BHO. The modification is the semi-circular cut-out along the right edge. When the BHO is pushed to its uppermost position this cut-out will align with the hole in the receiver through which the safety must pass during its installation. To perform the modification I installed the BHO in the usual manner, held it to its upper limit of travel, used a #2 pencil to scribe the safety hole onto the BHO, took the BHO out of the gun, and introduced it to Mr. Dremel.




Here's a picture of the guts of the receiver with the BHO installed. The modification to the BHO is readily visible.




Here's a shot of the safety hole in the receiver with the BHO installed and in its uppermost position. You can just see the edges of the cut-out in the BHO. You can also see the hole on the opposite side of the receiver into which the safety fits.




Finally, here's the right side of the receiver again but this time the BHO is being held down by the BHO spring in its lower most position.




This modification allows you to reassemble the shotgun in the same way as the 7.62x39 or the .308. The safety is the last thing to go into the receiver (except for the bolt carrier, bolt, and recoil spring - remember, if you have pieces left over, you've got a problem :D ).

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I will have to look it over and see how well it will work with my Kreb's Retainer plate.


In fact, I'm using a retainer plate. It works perfectly with this set up. I find the plate to be the easiest and most convenient method for preventing the hammer and trigger pins from walking out. It also makes reassembly easier. During reassembly I follow this sequence:


1. Drop in the trigger assembly

2. Drop in the bolt hold open

3. Using the dental floss trick pull the BHO spring into place

4. Put in the trigger pin

5. Swear a lot while pushing the hammer and its spring into place

6. Put in the hammer pin

--- a. Wipe the blood off my fingers from wrestling with the hammer and its spring

--- b. Apologize to my wife for swearing

--- c. Try to explain to my wife why I was swearing

7. Put in the retainer plate

8. Put in the safety

Edited by Steve in Allentown PA
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Well this seems a cleaver solution to a common S12 problem, I am surprised that it has not gotten more comments. I still need to study mine thought.


Any of the resident S12 jocks care to comment?

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Yep, it's easier to assemble everything if you can do it in the right order, without having to put the selector in first and then have to hook the spring leg on the BHO last. It's about the only way you can use the retainer plate or the L shaped retainer spring since you have to put that in before the selector.


Good pics.

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You basically loop the dental floss several times for strength through the circle in the spring and then down through the BHO slot in the receiver. While you are juggling three things with two hands you simultaneously pull down on the floss to get the spring circle lined up for the pin to slide through. When it's in you then simply cut or slide the floss free. You can also try to bend the end on the spring leg so it doesn't fall off the BHO lever so easily. Look here.




I think the floss method also has a video on Youtube somewhere showing it.

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I think the floss method also has a video on Youtube somewhere showing it.


I see that notching the BHO has been mentioned before on the forum.

Still the picture makes a nice addition!

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Thanks for the post and pictures. Tuesday evening, I was doing a conversion on my Saiga-12 and could not figure out how to install the safety lever with the BHO blocking the safety lever hole. I'm using the Tapco retaining plate, so the last part to go in is the safety lever or at least it was when I did my .223 Saiga conversion. I compared the BHOs' from the Saiga-12 and the Saiga .223 and they are completely different. So I'll just modify the BHO and I should be good to go.


I guess you could leave the BHO out but at the range I go to they want you to always have the bolt open (unless, of course, you are shooting the gun).

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  • 2 months later...
  • 3 months later...

I had to do this for my retainer plate, and it makes working on the gun easier.


Yours looks much cleaner than mine though, I had to knotch it with a bench grinder then work it with a file... :smoke:


While I was at it I cleaned up the part that makes contact with your hand and gave it a nice melt job then refinished it. :D

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I did this mod to my safety a month or so back and I'm also using a retainer plate. I hadn't seen this thread though. I think there's another one that talks about it somewhere in the forum, because I remember reading it a while back. Even though you have to mod the plate a little, it's definitely worth it.




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This post should be a sticky, so everyone doing an S12 conversion will know before-hand that this will be an issue. None of the videos or instructions I've seen mentioned this, and though I was diligent in my research prep, this cost me a day of frustration for what should be a 1-2 hour job total. Argh!! lol.

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Wheel I'm sorry you had such a hard time today bro. I guess I should have tried to talk you into adding one of these to your order....



I'm having some made in a machine shop now so I won't have to do the exchange thing any more.

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Just found this thread :rolleyes:


After cussing at my BHO/safety for awhile before I managed to get it all together, I will now tear it apart and mod the BHO.


I bought the shotgun retaining plate from Krebs, I cussed that a bit too, it was a PITA to get its hole lined up with the receiver's and get the safety in place.


EDIT: I did the BHO mod, I can now reassemble everything in two minutes :smoke:

Edited by ChileRelleno
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  • 5 months later...

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