[Scoro-550]

you could rotate it 180 degrees and drill new holes.

YES, Y-O-U CAN!

Works great on my SIG550 (500 mm barrel length) since 2005.
New holes in 1.0 and 1.1. (diam/mm)
No more damaged cases.
No more hyperfunction.
Perfect for handloads.

 

[Iamscotticus]

I think there are plenty of good reasons for manual opperation.

 

[ShootingSight]

Hi Matt,

Good to see you back on the forum again.

Art

 

[Reno]

Are these really different from a 556 design, other than the number and size of the holes?

Could you take a 556 plug, weld the holes and re-drill them?

Reno, what was the price if you got 10 people together? Even if you got 5 people who were willing to pay double, and each gets a spare that they can sell on GB.

They are different in the case of the internal diameter. The SG 552/553 have a smaller piston head than the 550/551/556, Josh posted a topic that covers this info.

So unfortunately you can't take a 553 gas valve and use it on a 556, I'm not sure about the SAPR's gas valve though.

For 10 valves it's $1410+VAT+International Shipping, which would put the total around $1525, give or take depending on the trade value of the US Dollar at the time of purchase.

 

[ShootingSight]

But now where is the interest? Matt has indicated that you can take a stock plug, twist it 180 degrees, and drill new holes. 0.040 and 0.043 (basically 1mm and 1.075mm) carbide drills are $5 each, so there is a $10 experiment. A little dremel and a grinding wheel ought to allow you to create the indents for the spring pin to engage in.

 

[Reno]

But now where is the interest? Matt has indicated that you can take a stock plug, twist it 180 degrees, and drill new holes. 0.040 and 0.043 (basically 1mm and 1.075mm) carbide drills are $5 each, so there is a $10 experiment. A little dremel and a grinding wheel ought to allow you to create the indents for the spring pin to engage in.

Well since this topic got split into two discussions I think the interest waned in both.

Don't think anyone wants to risk their own gas valves at a chance of screwing them up by trying to drill the new ports and I don't think anyone is willing or wanting to pay more than $100 for a new factory 4 position valve that only works on Swiss firearms.


But worry not, a plan is in the making to have the best of both worlds. :wink:

 

[ShootingSight]

You can't really screw it up, because if you don't like it, you just flip it back to the original position, and the buggered up holes will be on the bottom, out of the way.

 

[MrMcCrackin]

I still interested, but waiting to see how my sbr preforms at the range with and without the supressor

 

[MrMcCrackin]

Well the SBR ran 300 rounds unsupressed without issue.

I ran another 300 rounds suppressed without issue.

This is a 16" patrol cut down to 10.5" with the stock gas valve.

 

[Scoro-550]

Here I show you one method to find the dot for the new hole.

turn the rifle upside down, paint the valve with an EDDING, install it, pin through the gas-openings of the gasblock with a drill (or pointed steel in the max. Diameter for the gas hole), turn the valve into second Position, pin through again on the other side

to be on the safe side, do this three times on each side and you will find the best position for the new holes

It is that easy.

And read again Art´s comments. He is correct.

 

[Scoro-550]

Are these really different from a 556 design, other than the number and size of the holes?

Could you take a 556 plug, weld the holes and re-drill them?

Reno, what was the price if you got 10 people together? Even if you got 5 people who were willing to pay double, and each gets a spare that they can sell on GB.

They are different in the case of the internal diameter. The SG 552/553 have a smaller piston head than the 550/551/556, Josh posted a topic that covers this info.

So unfortunately you can't take a 553 gas valve and use it on a 556, I'm not sure about the SAPR's gas valve though.

For 10 valves it's $1410+VAT+International Shipping, which would put the total around $1525, give or take depending on the trade value of the US Dollar at the time of purchase.

The price für one SIG550/551 Special Gas Valve (1.0/1.1 or 1.1/1.2 mm, Stainless Steel) is 140 US $ plus shipment 15 US $.
(1 EURO = US $ 1.33)

 

[DP425]

Any progress on this?

(new valve plug or a smith to do mods)

 

[jkh62]

SIG factory 4 port valve-









My stock 556 / .223 SWAT valve

 

[jkh62]

I added the "extra" .9mm hole in a spare gas valve I had.

 

[jkh62]

Fun with some numbers using a Gas flow thru orifice calculator.

Based on a barrel / port pressure of 55,000 PSI and a flame temperature of 3300 F the flow for the various gas port diameters comes out as follows:

0.9mm / .035 diameter port = SCFM flow rate of 301.7
1.2mm / .047 diameter port = SCFM flow rate of 536.3
1.3mm / .051 diameter port = SCFM flow rate of 629.47

The 1.2mm port is the "standard" and the 1.3mm port is severe duty.
The 0.9mm port is the assumed suppressed port setting which shows a marked reduced flow rate.

Modding a stock SIG gas cylinder is the simple way to go if its machinable which I will find out shortly.

I look forward to testing it on my SIG 556 SWAT rifle and my AAC M4-2000 suppressor.

The calculator I used is online ~

http://www.tlv.com/global/TI/calculator/air-flow-rate-through-orifice.html




The stock factory 556 gas valve is tough but machinable with good tooling. I have yet to test fire the valve using my SWAT 556 and AAC M4-2000 suppressor.

The .9mm gas hole reduces the gas flow by a good margin.

 

[lilMAC25]

So this is dead as a production project? I'd like to use mine with a can, but don't have the capability to do the work myself on the valve.

Thanks

 

[datcha]

So this is dead as a production project? I'd like to use mine with a can, but don't have the capability to do the work myself on the valve.

Thanks

No it's not dead. :wink:

From what I hear, keep checking these forums for more information in the near future. 8)

 

[jkh62]

I am still waiting to test mine and see how it performs with my M4-2000 suppressor attached.

 

[lilMAC25]

Thanks guys! Mines a 556R, so the #'s might be different. I'd still buy a valve to give it a try though.

 

[atp]

From this Jan. 2014 article and the

, it seems the new Sig 556xi comes with a 3-position gas valve with normal, adverse, and suppressed settings. The gas block is definitely different but hopefully the valve is backwards compatible with the older 556 models. I can't tell from the small low-resolution pictures though.