porting what all is known

[going12220 125]

something that has come up a lot lately is on porting. it's just about always done (if needed) to make the gun cycle bird-shot. I've seen or read at least 4 schools of thought on the subject for the most part dealing with 19" guns. Of late what I've gotten are:

• 
   
  
• if possible don't mess with it, polish the internals better and you will most likely find it unnecessary.
  
• one group of some of the best brains in the Saiga field say add a 4th port at .086" diameter and leave the existing ports alone.
  
• a second group reportedly including the original designer say enlarge the existing posts to .093".
  
• the last one is more of just a photo seen of a members gun (post-apocalyptic) with several posts installed.
  

Should also reference shortening the gas system with re-porting nearer the chamber.

 

the only test I've seen to determine the need for porting is with shooting bird-shot from the hip with a fully loaded drum.

 

some of what I read indicates that any and all of the methods work when done properly and maybe in conjunction with other changes, so I don't believe there is only one right way.

 

Hitting briefly on part of the how to aspect of this work is first getting the gas block off.

1st putting witness marks on the barrel and gas block aids when reassembly for alignment.

A few for the methods that have been discussed are:

• 
   
  
• Using a press with a fixture to hold/support the gas block,
  
• Use of a metal shelf hanger from a hardware store wrapped with tape to protect the finish.
  
• And the use of brass punches, wood, and various other materials that will hopefully not mar the finish or damage the gun/gas block.
  

I’ve also seen the suggestion that the plug be installed to protect the threads on the gas block.

Should also note during reassembly if the gas block is being driven / beaten back in place to have the receiver supported (on wood maybe) so the stock tang isn’t bent or broken.

One more input on this area is I’ve read where ports have been changed, re-drilled, or added without removing the gas block. A small hole is drilled in the top of the gas block and a plug is screwed in when done. This one should most likely be left to the pros.

 

any other things or input on this?

 

seeing how it keeps coming up maybe one or more could work on making a good sticky on it for future members.

Edited September 1, 2010 by going12220

[evlblkwpnz 3,418]

Porting to .093" and adding one at that same size, was the biggest improvement of any mod I have done. So, there is also the 4 @ .093" school of thought. IIRC, someone stated that if the barrel was shortened to 10" without moving the block, the weapon would need 4 @ .103" or .108". I could be waaaay off as it has been some time since I read it It may have been Tony or Tom that said it in a SBS thread.

 

 

After my first 2 S12s and many frustrating range trips, there is a strict regimen of what my S12s will have done to them before going to the range. This includes 4 ports @ .093". It worked well with the last one (brand new), and other than Winchester Universal shells catching on the extractor slot, I have a working recipe. I mod'd the extractor slot before the last range trip and it seems to have solved that issue.

Edited September 1, 2010 by evlblkwpnz

[6500rpm 670]

BobAsh has a lot of good info here-

 

http://forum.saiga-12.com/index.php?showtopic=38318

[evlblkwpnz 3,418]

BobAsh has a lot of good info here-

 

http://forum.saiga-12.com/index.php?showtopic=38318

I have read that thread from start to finish twice.... and I just read it again. Thanks to you tricking me into reading that thread again, I am trying to decide whether to press onward with a few other stamps I wanted to get.... or throw an SBS stamp in the mix. Third time's the charm

[magsite20 1,664]

What do you guys recommend for cleaning the gas puck and ports on an S-12 ? They get downright filthy in no time. Thanks in advance.

 

 

I use a welding torch tip cleaner. I was actually able to open up the ports several sizes with the tip cleaner.

 

 

I don't think you are supposed to use anything but solvent (Hoppes #9) in the gas system. Oils act like cement...learned that one the hard way. I use a dental pick to clean the ports.

 

just keeping track of information as found

[BobAsh 582]

Who is the "original designer" you refer to?

 

 

[magsite20 1,664]

that unverified on my part statement came from this exchange:

to me it would be great to have this information posted in a way that some one looking for data on ports and porting could find it in one spot, there has been a lot of good data posted but it is sometimes under a different heading like SBS

 

I prefer to add a fourth port rather than open up the 3.

I don't like to open ports beyond .086"

Going above .086 is not really going to hurt anyting, but the larger you go, the more crap tends to build up in the gas block.

 

Tony

 

 

redfish28, You said your gun isn't severe... Before you remove your gas block and enlarge ports or add ports try contouring and polishing up some surfaces. If you can fire low brass from the hip out of a 20rd drum afterwards your probably good to go. There are a lot of other energy robing surface not mentioned as often. Does your bolt lock and unlock smoothly? When you pull your bolt carrier back is it chunky while unlocking the bolt? It should be nice and smooth. If it isn't you are losing MAJOR energy here alone.

 

Just because it appears the ports are covered doesn't mean they are. There is a beverled edge in the gas block to the barrel and ports. As long as the edge of the bevel isn't obsructing a port your not going to gain anything from enlarging the hole in the block itself. The beveled edge gives a much greater surface area for exit into chamber than the ports can put out... If you do take your block off you will see a circle of residue around the ports. If the edge of the residue circle isn't covering or partially covering one of the ports your good on the block itself. If a port is obstructed do like Cobra shows in the picture and enlarge the beveled edge to clear the port. Note the angle of his picture is from the underside, it is NOT the side you see while the block is on the gun and the edges of the through hole are still intact. If you absolutely feel you have to enlarge the hole in the block all the way through DO NOT cut into the back edge ( the edge you can look right at while looking into the block while on the gun). If you cut this area out you will increase the gas flow while using high brass ammo. Your plug is only so long... If you make the hole longer in the rear direction the plug won't be able to reach to cover it up and restrict it. That edge needs to stay intact. You will not gain anything from cutting it anyways so stay away.

 

If you do mess with the ports themselves listen to Tony and add an extra hole. Think of it this way... If you are straining sandy water through a screen but you want it to strain faster, do you make the holes bigger or do you add more holes? Add more holes... One extra will do just fine. Anymore and you very well may over gas your gun with low brass.

 

Also keep in mind... If you are enlarging ports to make up for a rough action... Once the gun breaks itself in you very well may have an over gassed gun. That is why you need to assure your problem isn't energy loss first instead of the lack of energy. Many increase energy to account for energy loss, and that isn't the way...

 

 

one of the things I've seen posted by one of the well know builders on this forum is don't enlarge the ports if you need to do anything to add gas is add a 4th port, and a small one at that. I'd read up before any change to the ports and if you don't need to do it would most likely be best. IMHO

based my reply on this, the other 2 gentlemen have a better knowledge of the system than I do.

 

 

I greatly respect both Mike & tony's opinions. They've been doing this much longer than myself. Tony is world class & Mike has studied Russian blue prints & designs from what I understand.

 

I'm just curios if there's empirical evidence, or if this is simply theory & hypothesis.

 

If we're just throwing names to prove facts, rather than depending on empirical evidence, the official RAA warranty repair center & Izhmash engineers led by Mikhail Timofeyevich Kalashnikov seem to think 3 @ .093 are reliable.

 

 

ETA, like I said, not trying to argue or undermine anyone, just attempting to establish the most through understanding of theory of operation possible.

 

 

Pauly all I know is if this is wrong I'm in good company as are you.

to me it makes sense so that's the theory I'm going with on this one.

or as the guy on mythbusters says "I reject your reality and insert my own."

[BobAsh 582]

If we're just throwing names to prove facts, rather than depending on empirical evidence, the official RAA warranty repair center & Izhmash engineers led by Mikhail Timofeyevich Kalashnikov seem to think 3 @ .093 are reliable.

 

1) Tony's opinion is based on empirical data collected while building and testing thousands of guns. It's not speculation.

 

2) We all know that the factory configuration is not reliable with all ammo. That's the whole reason for this debate, right? After all, the S12 was designed to be used with military ammo which has no where near the power variations that we see in commercially-available stuff.

 

Seriously though, do whatever you want; it's your gun.