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SA Victor .308 low pressure gas block adjustment

Bear007

Master Class
My new SA Victor .308 shoots .308 win cartridges absolutely fine. Most shells eject out at 3-4:30 o'clock while some are slightly over pressure ejecting out at 2 o'clock.

THE PROBLEM is I have a pile of ZSR 7.62 that will shoot but has very low pressure ejecting cartridges out at 5-5:30 o'clock, won't lock the bcg open on a single shot and has a few other problems, fte and trys to stuff another in the chamber jamming the 2 together. NOT A BIG DEAL, I know it's low chamber pressure problem with ZSR ammo.

THE QUESTION is whether the adjustable gas block can increase pressure to the bcg using the Mode 3 adjustable screw? Or does the stock Mode 1 screw already divert/send the max possible pressure that can be sent to the bcg?

Does a lighter buffer or buffer spring exist that may work for the lower pressure ammo? Or is this not a direction to go either?

I'm fairly new to the AR world and I've just been reading, learning and having fun as I go. Just curious if there is a fairly easy way to accomplish this since 7.62 ammo is more available. I'm also not assuming all 7.62 ammo is as low pressure as this ZSR ammo either.

Appreciate your thoughts!
 

Talyn

Ronin
Founding Member
I'll bet the gas block is set to an intermediate setting at the factory to provide for propoer function with the ammo they use for testing.

That being said there should be room for adjustment to provide more gas for less powerful ammo.

My .02
 
I don't have any SA rifles, but did check out their site for info. I found out it has an adjustable gb and a heavy tungsten buffer. The H buffer is probably for adding suppressors. either open up the gb another notch or get a standard weight buffer. I don't know how many adjustments it has. @Talyn has a correct answer!
 

Bear007

Master Class
I don't have any SA rifles, but did check out their site for info. I found out it has an adjustable gb and a heavy tungsten buffer. The H buffer is probably for adding suppressors. either open up the gb another notch or get a standard weight buffer. I don't know how many adjustments it has. @Talyn has a correct answer!
I did not know the buffer was a heavy tungsten. That would be the way to go to start with. Then it would be simple to switch back and forth. Thnx
 

Talyn

Ronin
Founding Member
Your rifle may be set properly already.

One should adjust the gas to the point where it will not function, then back off (more gas) a couple clicks in order to function with your prefered ammo, plus less powerful ammo (i.e Russian steel-cased) if you have to use some.

Regardless of the ejection pattern you should have it set to function with all your available ammo.

My .02.

BTW- with an adjustable gas block there's not reason to switch out buffers since the adjustable gas block is there for a reason.
 
Your rifle may be set properly already.

One should adjust the gas to the point where it will not function, then back off (more gas) a couple clicks in order to function with your prefered ammo, plus less powerful ammo (i.e Russian steel-cased) if you have to use some.

Regardless of the ejection pattern you should have it set to function with all your available ammo.

My .02.

BTW- with an adjustable gas block there's not reason to switch out buffers since the adjustable gas block is there for a reason.
Is the gb a click or screw type? Hopefully they would have more than 3 settings as some other companies have? Gas port size has its part/affect
 

Bear007

Master Class
Is the gb a click or screw type? Hopefully they would have more than 3 settings as some other companies have? Gas port size has its part/affect
Gas block comes set in MODE 1 which is a regular set screw you can buy at any hardware store screwed in completely. MODE 2 has 3 different set screws with different size holes for over pressure situations. MODE 3 is a set screw with a cone on the end you screw in fully and start backing it out for more pressure. Once you find your point you have to remove it, counting your turns, apply blue locktite and re insert it.

Since I checked my buffer and it isn't heavy, it's 3.8 oz with a sliding weight, I guess I'll have to work with the GB.

My only thought or concern is that IF the MODE 1 set screw already sends the max amount of pressure available then Modes 2 & 3 will only divert some amount of pressure less than MODE 1 which won't work at all.

One day this week I'll sit down at the range taking single shots with the MODE 3 set screw to see if I can make it work but I'm starting to think it may not.

Normal .308 ammo can have up to 62,000 psi according to SAAMI. The 7.62 NATO says pressures up to 60,000 I think, ZSR says on their website their 7.62 chamber pressure is around 55,000 if I remember correctly. That's a pretty significant difference.

Still just having a mental exercise and some fun seeing if I can get it to work. Thnx
 
Gas block comes set in MODE 1 which is a regular set screw you can buy at any hardware store screwed in completely. MODE 2 has 3 different set screws with different size holes for over pressure situations. MODE 3 is a set screw with a cone on the end you screw in fully and start backing it out for more pressure. Once you find your point you have to remove it, counting your turns, apply blue locktite and re insert it.

Since I checked my buffer and it isn't heavy, it's 3.8 oz with a sliding weight, I guess I'll have to work with the GB.

My only thought or concern is that IF the MODE 1 set screw already sends the max amount of pressure available then Modes 2 & 3 will only divert some amount of pressure less than MODE 1 which won't work at all.

One day this week I'll sit down at the range taking single shots with the MODE 3 set screw to see if I can make it work but I'm starting to think it may not.

Normal .308 ammo can have up to 62,000 psi according to SAAMI. The 7.62 NATO says pressures up to 60,000 I think, ZSR says on their website their 7.62 chamber pressure is around 55,000 if I remember correctly. That's a pretty significant difference.

Still just having a mental exercise and some fun seeing if I can get it to work. Thnx
SA site states heavy tungsten, so don't know why there would be something different?
 

Bear007

Master Class
SA site states heavy tungsten, so don't know why there would be something different?
Not sure either but it does shoot any .308 I've feed it so far. Might look at a box or 2 of some different 7.62 from my local store to see how it functions.
 

Talyn

Ronin
Founding Member
Gas block comes set in MODE 1 which is a regular set screw you can buy at any hardware store screwed in completely. MODE 2 has 3 different set screws with different size holes for over pressure situations. MODE 3 is a set screw with a cone on the end you screw in fully and start backing it out for more pressure. Once you find your point you have to remove it, counting your turns, apply blue locktite and re insert it.
Surprised SA went with a set-screw gas block.
 
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Bear007

Master Class
This morning I compared the ar-10 buffer to my Ruger AR-556 buffer. They are the same size. The Ruger buffer weighs in at 2.9 oz (probably 3.0) while the SA AR-10 weighs 3.8 oz. Both are about 3.3" long and the shaft diameter is 0.7"

The AR-10 looks like the housing is a heavier metal, which is probably the tungsten, and has fewer weights so they slide more.

It works the way it is for .308 but I'm just wondering why everything I read says AR-10s need heavier buffers???

What I've learned so far - AR-10s are a LOT more finicky than AR-15s. 🙄
 

Talyn

Ronin
Founding Member
What I've learned so far - AR-10s are a LOT more finicky than AR-15s. 🙄
I wouldn't assume that. There is no standard "spec" for the AR-10/.308 platforms so each manufacturer is making their own interpretation of an .308/7.62x51 AR-type rifle.

There is a variety of AR-10/.308 rifles ranging from low to high end out there.

Also, IMO during these times of high demand QC may slip and product may go out the door that's lower quality than during normal times.

I don't see your SA Victor being finicky just based on ejection pattern differences due to different brands of ammo that you're using. But, another maker(s) of AR-10/.308s may have rifles that have gas blocks that are easier to adjust than your Victor.

My .02
 

Bear007

Master Class
I wouldn't assume that. There is no standard "spec" for the AR-10/.308 platforms so each manufacturer is making their own interpretation of an .308/7.62x51 AR-type rifle.

There is a variety of AR-10/.308 rifles ranging from low to high end out there.

Also, IMO during these times of high demand QC may slip and product may go out the door that's lower quality than during normal times.

I don't see your SA Victor being finicky just based on ejection pattern differences due to different brands of ammo that you're using. But, another maker(s) of AR-10/.308s may have rifles that have gas blocks that are easier to adjust than your Victor.

My .02
Maybe finicky isn't the right word. I'm not saying my rifle has any problems. It shoots fantastic with .308 150 gr ammo. I haven't tried my .308 180 gr yet. It fails miserably with 7.62 149 gr.

Like I've said, I'm just reading and learning about the AR-10 plarform since I'm new to it. It just seems more confusing/particular to me than AR-15s probably because there is no standard spec and some components in my rifle seem to contradict information I've read on individuals attempting to build AR-10s and some general info with people having problems.

On the other hand, there is a wider variety on the types of .308/7.62 ammo. I have 55 gr varmint accelerators up to 180 gr., then you throw in 7.62.

The only ammo my 556 didn't like so far was Tulammo. It was stripping lead pieces off the bullets and getting all through the inside. It still kept on shooting until it finally jambed on lead pieces.
 
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