Got the gas block off and ready to drill - just a couple of questions

[negev5021 25]

I have determined I am undergassed and ready to enlarge gas port holes. I have taken the gas block off and upon visual inspection I don't think there is room to add a 4th hole. My plan is to enlarge the 3 existing holes and hope for the best. I don't think I am too shy of having adequate gas, I am cycling federal value pack ammo, but not 100% and I am using light weight trigger spring and recoil spring. My questions are:

 

What would the drill bit size be to best solve without drilling 4th hole?

 

The one thing I am totally unsure of is the gas "bleed" hole on the gas block. I read the "fixing the vodka special thread" in which they tig welded the bleed hole shut. Should I do that while I am at it?

 

thanks!

Edited November 26, 2009 by negev5021

[aresv 49]

The bleed hole on the side doesn't really make any difference. By the time the puck has moved far enough aft to uncover that hole, the piston is already well on its way. I think somebody even did a test where they covered up the hole with some scotch tape and went shooting, and the tape didn't get blown off.

 

The bleed hole also helps a bit by letting fouling and junk out of the gas chamber. Welding it up won't really hurt anything, but it also won't help much either.

[gtnichols 51]

There is an early thread on this, where it is reccomended to angle the existing holes back somewhat and enlarge the holes. since you have it open you should be able to test the diameter, 1/16th" or 3/32" ?? cobalt drill bits help here too. ensuring smooth drilling.

[thealmightysam 2]

What's the approximate diameter of the current holes?

 

One of the members of another site I'm a part of opened the gas ports on his 3-hole gun to .093 with good luck. I seem to remember reading that 4-port guns are typically manufactured at .073, so 3 ports at .093 is just a touch more gas than that (about 13% more).

[negev5021 25]

Thanks guys - what does .093 equate to in bit size?

[Frank Rizzo 8]

Thanks guys - what does .093 equate to in bit size?

 

#43 = 0.0935"

[volkov 318]

I literally just went through this process..

 

While I can't give you the specifics on sizes (I don't really care, kind of play it by ear) I can give you the process I went through..

 

My gun was undergassed.. simple enough, I found the drill bit that was literally one size in your standard kit too big for the current hole and drilled all three holes.. made very very little difference.. so I went home, went one size higher, and drilled out the top hole (in the sort of triangle shape they were in) one size bigger.. Gun works great now but is obviously not overgassed as it still will not fire birdshot on low gas settings.. Also on my particular gun the second two holes, which I consider the base of the triangle are partially obscured by the gas block anyway, hence why I drilled the "top" hole in the traingle out the most.. What I'm saying is.. the specific size doesn't matter.. what matters is yours has holes that are too small.. so go bigger size by size until it works.. theres really not one answer for all guns- I'd expect vodka special or no, the were all drilled by the same drill in the first place.. even if the gas holes are all the same size they might be positioned differently and there are other factors to play into it.

 

 

Can't remember who said it, but when I was worried about drilling someone said something along the lines of "I've never heard of an overgassed saiga 12".. Wise words indeed.

[flyinlow78 0]

 

My gun was undergassed.. simple enough, I found the drill bit that was literally one size in your standard kit too big for the current hole and drilled all three holes.. made very very little difference..

 

 

My experiences are exactly the same as Volkov...one drill bit too big for the hole, and it runs 9/10 rounds just fine on the lighter loads. Buck shot cycles fine, but it still isn't throwing the brass very far...3-5 feet max. On the light loads, you can see the shells falling 2-3 feet away, just barely getting kicked out of the gun.

 

I'm going to have to go up 1 more size too. Given how it really doesn't make a huge difference to go up just one size, I'd go 2 sizes right away if I had it to do over again. Then again, it was easy enough that it isn't a problem to redo it. I just don't want to mess up my newly finished Norrell finish taking it apart again.

[negev5021 25]

Ok guys took your advise - my original holes were 5/64, so the 3/32 wasthe next bit in the quiver... drilled out all three and took it out to test, shot 50 roundes with no FTE - actually there was one, however different from my prior FTE, this one didnot eject all the way out, but another round was already chambered!? MOre like a stovepipe.

 

I am back to my factory recoil spring, which makes me feel better, too. I am thinking of replacing my hammer spring back to original as well, but not sure yet. I am a little bummed that it finally works because my OCD lived well with such a a propblematic shotgun - don't know what to do with myself now... ahh magwell is on the horizon.

 

To all interested/contemplating doing this fix let it be known I am a mechanical retard and was able to accomplish this in about a hour total. Someone else posted that if they could do it, anyone can, which gave me the hope - and really anyone can do this.

Edited November 30, 2009 by negev5021

[volkov 318]

 

 

I am back to my factory recoil spring, which makes me feel better, too. I am thinking of replacing my hammer spring back to original as well, but not sure yet. I am a little bummed that it finally works because my OCD lived well with such a a propblematic shotgun - don't know what to do with myself now... ahh magwell is on the horizon.

 

 

 

Haha.. thats the exact thing that happened to me now mines fixed I don't know what to do

[Spartacus 1,619]

I know about the thread that talks about using a shelf bracket to pound the gas block off.

 

How did you guys do it?

 

Anybody have to use a press to get it off or back on?

[negev5021 25]

I know about the thread that talks about using a shelf bracket to pound the gas block off.

 

How did you guys do it?

 

Anybody have to use a press to get it off or back on?

 

 

I did use the shelf bracket - happened to be in arms reach on the work bench. I also used the handle of a hammer - placed it on the edge and hit it with another heavy hammer. Imagine barrel down, chin on recoil pad, hammerin away...

Edited November 30, 2009 by negev5021

[flyinlow78 0]

I used a T-square and a rubber mallet.

[Spartacus 1,619]

Thanks guys, sounds like it was pretty easy.

 

I still consider my S12 to be in the break-in phase, but nice to know it's easy

to pull the gas block off if I need to down the road.

[volkov 318]

I was drunk, used a hammer, it worked.. few scratches though.. woops.

[gtnichols 51]

I used a tight grained oak block/board about 1 foot long, 2"x 2" and a big hammer with the barrel on a piece of 1" thick pine on the floor.

Hitting down very hard with a framing hammer, a different place on the block each time,..once it started moving it got easier.

To put it back,..I took off the butt stock and used a couple pieces of 2 x 4 on the bottom of the receiver (on the floor) so the tang wouldn't hit the floor.

Line up of the block was easier than I thought, It needs to be lined up before it is driven all the way home. I used the original pins that came out, and hammered 'em back in with a punch set after de-burring the ends with sandpaper.

Edited December 1, 2009 by Gas Giant