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SBS 12 and his little brother Mr. Mossberg


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Got my stamp back on July 6th for my s12 SBS so I started the transformation.

This is where it's at right now. with his little brother Mr. Mossberg. ( built that one in 2013)

 

Tme line on the stamp was:

 

Sumitted Dec. 28th 2015

Approved June 24th 2016

Recieved July 6th

Cut the barrel on my lathe yesterday down to 12 inches.

Gun runs High brass 2 3/4 and 3 inch Mags. no problem.

 

Right now it DOES NOT run the cheapo wally world ammo.

It did before the chopping of the barrel.

 

So my next question is this.

How the HELL do I get hte as block off?

I drove out the pins carefull not to lose anything.

Did the shelf bracket trick with a 2 and also 4 lbs cross peen hammer it didn't move so I finallt stopped.

 

Should I try the air hammer trick?

I'd have to borrow a buddy of mine's air hammer since I dont own one.

Also it's not that important to me either since it works as is I can just shoot the wally world stuff up in Mr. Mossberg.

 

THis is where it's at now.

With his little brother Mr. Mossberg. at 19 inches OAL and 10 inch barrel.

20160717_173636_zpsnjvnrbg5.jpg

 

This is where it's going when done.

 

20160716_151038_zpsp5er9qox.jpg

 

Any other ideas on the gas block before I put a air hammer to it?

I really would like to get it to run the cheapo wally world junk. but since the gun runs as is with the barrel at 12 inches I'm going to locate the 5.5mm rear trunion for the 100 series 74M so I can complete the conversion.

 

Anyone know where to buy a 5.5mm rear trunion?

 

Also gun isn't broke in yet less then 100 rounds through it. all wally world low brass until todays test fire.

 

Rich

Edited by armalite_ar50
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Well, while I'm not too familiar with making a SBS Saiga run, I can tell you that my factory Saiga 12 did not run Winchester reliably, either. What I did is purchase a Tac-47 Autoplug. That solved that issue. However, I must add that while the Winchester cheap box did not run with factory components, the Federal value pack did. Now, obviously, I wouldn't know about "your" particular Walmart, but ours stocks the Federal right next to the Winchester, so perhaps give that a go if you can?

 

Also, just wondering, why not perform the pistol grip conversion? I can guarantee it's easier than what you've already done.

Edited by forsaken352
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I am going to do that as soon as I land a 5.5mm rear trunnion.

 

I have a lot to do yet. I tested it today like I said it runs the high brass and 3 inchers fine but is a hand cycle on the cheap stuff.

 

I've read the thread on the SBS conversions like 5 times while I waited on the stamp to come back.

So my next step is to close off the gas port.

I ran a tap into it tonight and I'll get a hex plug for it tomorrow then hopefully get to test fire it again on Tue.

 

If that helps I'll either weld it over or lock tight the plug. 

Tromix pretty much says it's not needed on the SBS

 

I need to get my dremmel back from my friend  so I can polish the trigger group. He's the same guy that I would need to borrow the air hammer from to get the gas block off if I can't get this thing running low brass and need to move the gas block back.

 

One up side was my 1st S12 was a vodka special.

I got that one running with the wally world crap and out of the box it would short stroke everything I fed it.

So this one will run in the end.

I'm not opposed to moving the gas block back but the gun isn't even broke in yet and I'm able to shoot it with decent ammo.

 

The next on the list is

Plug the gas vent on the gas tube.

Polish out the trigger system

thread the barrel

5.5mm rear trunnion

Air hammer the gas block and check/open the ports. I can only see three and haven't checked with a wire yet for # 4

 

Then finally make the conversion over to the folding stock and pistol grip.

 

Somewhere in there I gotta get some of those metal 10 rounders from CSS too.

 

Believe it or not I'm more afraid of the conversion on the PG then anything. It's the one thing I 've never done.

I sold my last S12 after I got it running to buy a silencer.

 

Since then I bought a pretty decent lathe and every NFA stamp has been a F1

 

The Mossberg was a real pain to do and I wouldn't have tried it without the lathe I'd of just bought a SBS.

THe S12 Just fit between the chuck and tail stock to part the barrel.  Hardest part there was centering it up since it's a square sheet metal reciever.

 

Rich

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"Believe it or not I'm more afraid of the conversion on the PG then anything. It's the one thing I 've never done.

I sold my last S12 after I got it running to buy a silencer."

 

 

Extremely easy. For the most part, you can get away with simply using a drill. However, if they did not cut the pistol grip hole at the factory, then that requires the use of (usually) a Dremel. Dremels also make it easier. Aside from that, it's pretty much plug 'n play as far as AK accessories go. Never replaced a rear trunnion myself, but doesn't look too difficult with the right tools, if that's what you're trying for. I encourage you to research and perform the conversion, especially if the pistol grip hole is visible from the inside of your receiver under the current fire control group. That would be like a walk in the park. If I remember correctly, the 12 doesn't even have the spot welds that the .308 has, so the trigger guard plate is only held in by 3 rivets.

Edited by forsaken352
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Well, while I'm not too familiar with making a SBS Saiga run, I can tell you that my factory Saiga 12 did not run Winchester reliably, either. What I did is purchase a Tac-47 Autoplug. That solved that issue. However, I must add that while the Winchester cheap box did not run with factory components, the Federal value pack did. Now, obviously, I wouldn't know about "your" particular Walmart, but ours stocks the Federal right next to the Winchester, so perhaps give that a go if you can?

 

Also, just wondering, why not perform the pistol grip conversion? I can guarantee it's easier than what you've already done.

I'm not understanding how the Autoplug helped it run a wider range of loads. It does not add gas or reduce resistance/friction. The factory gas regulator and the AP both regulate the gas that is available to the system, that is all they do. Did you happen to do something else when the AP was added? Clean the puck, lube the weapon, etc?

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Well, while I'm not too familiar with making a SBS Saiga run, I can tell you that my factory Saiga 12 did not run Winchester reliably, either. What I did is purchase a Tac-47 Autoplug. That solved that issue. However, I must add that while the Winchester cheap box did not run with factory components, the Federal value pack did. Now, obviously, I wouldn't know about "your" particular Walmart, but ours stocks the Federal right next to the Winchester, so perhaps give that a go if you can?

 

Also, just wondering, why not perform the pistol grip conversion? I can guarantee it's easier than what you've already done.

I'm not understanding how the Autoplug helped it run a wider range of loads. It does not add gas or reduce resistance/friction. The factory gas regulator and the AP both regulate the gas that is available to the system, that is all they do. Did you happen to do something else when the AP was added? Clean the puck, lube the weapon, etc?

 

Nope. Installed the plug, adjusted as per their instructions, and it began running Winchester value packs. I remember having ran through some Federal one day on the factory plug, then attempting to run some Winchester directly afterwards. Of course, it failed, but after a quick switch of the plugs, it began running like a champ.

 

ETA: It did not COMPLETELY remedy the problem. I do recall having a couple of failures to eject after installing it, but for the vast majority, it ran 'em.

 

I remember using this video as a guide on tuning it:

https://www.youtube.com/watch?v=7DIeY5Q2pjs

Edited by forsaken352
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I don't understand how a auto plug works either.

 

I'll have to watch the video when i get home.

I'm pretty much a minimalist when it comes to firearms. I don't own anything with rails and such. And plan on a nice stream lined forearm.

 

Im a firm believer in keeping guns as factory as possible.

I'm no sbs guru either. But i had a good learning lesson on my 1st saiga. I know to also only make one change at a time. So if something stops working i know what went wrong.

 

So after i plug the gas vent I'll shoot it some more then start the trigger polish. Once the gun is running as best i feel i can get it. I'll be chopping the trunnion and weld on the 5.5mm sidefolder and do the conversion on the PG and trigger.

 

Rich

Edited for my droids auto correct. .....

Edited by armalite_ar50
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Well polished the bolt kinda OK.

I didn't have my dremmel so I chucked the dremmel bit up in the drill press and went to town on the bolt.

 

Once the park was off it it didn't have tool marks. It had tool chatter marks.

Either the tooling was at the end of it's life or the bolt came out of the jig during machining.

It looked like a drunk russian hooker played shark week on it for a month with her lips.

 

I'm really surprised the gun ran at all. It must have good gas ports on it since out of the box it ran the junk wally world stuff, and at 12 inches runs 3 inch and 2 3/4 high brass.

 

So far I plugged the gas bleed port.

Threaded it 8-32 H2 and ran the plug in then backed it out until I couldn't feel it with my finger any more then hit it with blue lock tite.

I also checked that the gas puck slid freely back and forth without hitting the threaded plug.

 

Then I polished the bolt best I could with the drill press.

This is where the gun is at now.

 

20160720_164813_zpskswbyiqe.jpg

 

Just shy of ejecting the federal and winchester wally world bulk crap.

Got my dremmel back yesterday and test fired it today.

Haven't got to use the dremmel on it yet.

 

Above pic is where I sit now.

Just shy of ejecting and still catching the empty.

This is a far cry from where it started. Before it was feeding the empty back into the barrel.

The bolt was also only cycling about a inch back.

Now it's almost all the way out of the breech.

 

I'll polish the trigger and rails and everything else in the receiver like I did the other S12 and she should run baby run.

 

Work the next three days and I'm on vay kay the next week.

I hope to get back to it on Sunday night so i can work with it during my week off of work.

 

Rich

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Polishing the rails was useful. Polishing the bolt is almost nothing. Profiling the bolt and hammer are valuable. I'd unplug the gas vent, and open ports if needed -after- Profiling the HAMMER.   At this point I would not suggest DIY bolt profiling to you, but Cobra or Jack would do well by you.

 

You are doing a lot of hard work which probably won't do much, to avoid the easy work known to be effective.

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Polishing the rails was useful. Polishing the bolt is almost nothing. Profiling the bolt and hammer are valuable. I'd unplug the gas vent, and open ports if needed -after- Profiling the HAMMER.   At this point I would not suggest DIY bolt profiling to you, but Cobra or Jack would do well by you.

 

You are doing a lot of hard work which probably won't do much, to avoid the easy work known to be effective.

 

Bolt and trigger profile won't be any harder on this gun then the last.

Last wouldn't even shoot 3 inch when I started.

This one ran out of the box.

 

Rich

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Got my stamp back on July 6th for my s12 SBS so I started the transformation.

This is where it's at right now. with his little brother Mr. Mossberg. ( built that one in 2013)

 

Tme line on the stamp was:

 

Sumitted Dec. 28th 2015

Approved June 24th 2016

Recieved July 6th

Cut the barrel on my lathe yesterday down to 12 inches.

Gun runs High brass 2 3/4 and 3 inch Mags. no problem.

 

Right now it DOES NOT run the cheapo wally world ammo.

It did before the chopping of the barrel.

 

So my next question is this.

How the HELL do I get hte as block off?

I drove out the pins carefull not to lose anything.

Did the shelf bracket trick with a 2 and also 4 lbs cross peen hammer it didn't move so I finallt stopped.

 

Should I try the air hammer trick?

I'd have to borrow a buddy of mine's air hammer since I dont own one.

Also it's not that important to me either since it works as is I can just shoot the wally world stuff up in Mr. Mossberg.

 

THis is where it's at now.

With his little brother Mr. Mossberg. at 19 inches OAL and 10 inch barrel.

20160717_173636_zpsnjvnrbg5.jpg

 

This is where it's going when done.

 

20160716_151038_zpsp5er9qox.jpg

 

Any other ideas on the gas block before I put a air hammer to it?

I really would like to get it to run the cheapo wally world junk. but since the gun runs as is with the barrel at 12 inches I'm going to locate the 5.5mm rear trunion for the 100 series 74M so I can complete the conversion.

 

Anyone know where to buy a 5.5mm rear trunion?

 

Also gun isn't broke in yet less then 100 rounds through it. all wally world low brass until todays test fire.

 

Rich

Clean, Very nice! 

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Thanks DPH.

Note the shiny spot by the barrel nut of Mr. Mossberg.

I missed it when I reparked the rest of the gun.

It is the ring that holds the front pump grip on.

you have to turn that down on the lathe to get it to fit since the barrel is a ton thicker that far back.

 

NOW the S12.....!
 

It RUNS!!!!!!!!!!

 

Got it out today after getting my dremmel back from my buddy and polishing all the parts I couldn't get to with the buffer in the drill press.

 

Drops the empties right at your feet.

Gas vent is still plugged as of now.

I'm going to be headed up to my friends place on private land where I can shoot it all I want and try it with the vent unplugged.

But for now just cleaning the chatter marks off the inside of the S12 did the trick.

Didn't re profile anything accept the hammer and the back of the carrier where it strikes and resets the hammer.

Also buffed the latch that catches the hammer and profiled the hammer where it strikes that latch since it was almost square and sharp.

 

SO now I move on to the conversion

TEST for function again

thread the barrel

weld the 4 left over holes from moving everything forward.

Blast and repark it.

I'm either going to vent the factory hand guard or put one of those AMD 65 metal ones on it like Distal has on his S17.

It looks like it belongs there.

 

I ordered the 5.5mm trunnion and a rear stock ( I probably won't use) but the seller wanted 165.00 for just the trunnion or 200 for everything.

So I just took everything and I'll see what I like better, but I'm pretty set on the triangle and I got the limb saver when I bought it off of UZITALK

last winter.

Got this coming for it.

http://www.ebay.com/itm/122028246581?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

RIch

PS: I'm stoked that it is functioning. this thing throws the 3 inches into the next county and drops the bulk pack stuff right at my feet!

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Oh good. I was worried you would leave an SBS with the unrestored trigger location. It just hurt a little. Props for having the stuff on hand to do home parkerization and bluing.

 

I haven't taken that on yet.


p.s. Are you using the gas adjuster wide open with the 3" shells? A healthy ejection pattern would be about 3'-15' so it sounds like you are still a little weak for confidence with the light shells, and under restricted with the really hot ones.

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Haven't tried it on 1 since I chopped it.

As far and the 3 inchers are going on 2 I'm sure it will be fine on setting one. I only ran 3 of them out of it 6 total.

 

When I get to private property where I can load more then 3 in the mag I'll give it a good workout.

but it ran 3 of the federals and 3 of the Winchester wally world stuff today no problemo.

 

I'm really hoping to just let the gun finish breaking it's self in now that it's running.

 

No intention of not converting it.

My goal is the pix with the triangle krink stock as seen above.

 

But I wanted to have it run 1st that way if it doesn't run after the conversion I know it's something I did not the original config.

 

After I convert it over to PG and 5.5mm rear trunnion I'll test it some more and hopefully it will still work.

 

But as of now I have a gun that runs so I have a "YES IT DOES" starting point to go back to.

 

Parkerizing is easy, real easy.

I've done everything from a McMillian 50 BMG to the 50 packs of UZI mags from RTG to everything in between.

Right along with some transferable MG's.

Prep is key.

 

I'm going to start anodizing this fall.

 

I have some other F1 projects going that will need anodized to be finished.

 

As always I've got like 6 gun projects going at once.

 

Rich

Edited by armalite_ar50
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  • 2 weeks later...

This showed up last week.

 

20160808_110230_zpsrbw7plwn.jpg

 

Just have to figure out what stock I want I'm thinking the triangle stock.

Also anyone have a diagram or detailed pix of how all the small parts go together?

 

I want to use the stock latch also I know sometimes the don't line up or work right on the S12 I'll see about that.

I have no idea when I'll even get to it I am so busy right now with orders and my day job.

Also buying back a 1919a6 I sold to a friend 14 years ago.

 

So anyways, anyone got a link or pix to how the trunnion gets assembled?

 

Rich

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  • 2 months later...

Just bringing this to the top.

Only real update is I have everything for the conversion.

 

I did manage to turn out a threading tap on my lathe for the barrel so I can make and thread my own muzzle device.

I still need to mill the flutes into it and heat treat it.

 

Also need to build a rivet press for the rear trunion rivets since the bolt cutter trick won't work.

 

Been to busy with anything to really work on it accept in my head.

 

OH, and thanks Evl I figure I'll have to carve something out of steel for the stock latch.

you did save me time with the heads up though so again thanks.

 

I figure once I have my jeep back together for winter I'll have more time to work on it anf my other F1's along wih a title one build I have going also.

 

Rich

Edited by armalite_ar50
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