All MicroMOA Govnah's come standard with 2 regulator plates.
That said, for 10.3" - 12.5" barrels, the 2 position versions come with a .049"/.070" regulator plate and a .052"/.073" port.
You can see in the link below that I recently worked on a local shooter's Noveske SB upper on a full auto M16 lower this past weekend.
http://www.ar15.com/forums/t_6_23/412056_Took_my_M16_to_the_range____NOVESKE_UPPER_D OES_NOT_WORK___FACTORY_DEFECT___UPDATE_pg2.html He ordered the upper after Sandy Hook and got it I guess a month or so back.
It had a .059" port for suppressed and a .120" port for unsuppressed (obviously relying on the barrel's gas port - which was .082").
I have done a lot of testing on various 10.5" uppers as you can read in my article on my site here:
Why so much variations in port sizes? | MicroMOA As mentioned in my link above:
All 3 of those uppers have 10.5″ barrels in them. We tested them with the same ammo (LC M855), BCG and lower (lower had H2 buffer installed, standard power (white) Sprinco spring. Uppers were dry and not lubed for the testing since varying amounts of lube can skew the test results.
All 3 ended up locking the bolt back on an empty mag consistently at 3 different port sizes:
The top one was .076″
The middle one was .063″
The bottom one was .070″
The top barrel was a junk barrel and my pre-determined port sizes for my 2 position would be too small for that barrel. Fortunately, most people that buy my block don't buy junk and I have yet to have a customer tell me that the port sizes I have selected do not work.
Considering that most people don't read instructions - that INCLUDES ME. We always ship Govnah's out with the plates with the larger ports installed so that it has a higher possibility of working since we don't always know:
1. the port size of the customer's barrel
2. buffer used
3. spring used
4. in addition could be an A5 or Rifle length stock which adds more variables to 2 and 3
5. ammo used
6. type of carrier used.
As mentioned on my site, all testing was done using LC M855 with a full auto lower and a milspec configuration of an H2 buffer and standard power spring.
Using that configuration, you can see in the video below taken at high speed (480FPS) showing the difference between regulated and unregulated. Both are shot at the same 480 FPS and the first shot is at the same time.
Both videos are the exact same gun, fired in full auto 10 rounds, M855, H2 buffers in BOTH. Only difference is the one in the lower right is regulated.
There was so much gas coming out of the unregulated that it fouled up the glass in front of the camera. If you look closely, you can also see more recoil on the unregulated. I could feel the buffer bottoming out.
VS the regulated, you can barely make out any gas coming out of the ejection port and 3 rounds are fired after the unregulated has finished its 10 rounds since it is about 200 RPM slower when regulated vs unregulated.
Below are some links to a two part article on the MicroMOA Govnah that covers the background and Govnah solution and testing quite well - all with RoF informatioin.
Part1
MicroMOA?s ?Govnah? Adjustable Gas Block (Pt 1 of 2) - RECOIL Part 2
MicroMOA?s ?Govnah? Adjustable Gas Block (Pt 2 of 2) - RECOIL You can see that the Govnah is based on actual port sizes from NO port to whatever you want to drill. In the event that your barrel is overgassed and you don't want to run suppressed, I personally would have 1 port match your barrel's gas port which would be your adverse position (for use when dirty or using weak ammo) and you would also use that to install/align the block for installation then work your way up to a port size that locks your bolt back on the other port for optimal unsuppressed.
Then use the 3rd position for suppressed use.
Or use a two position if you just want suppressed and max gas.
In regards to having an adverse position - which is really just the port size in the barrel, some may question why bother with adverse.
We have a State SWAT team that loves it for the sole fact that they can now run their Simunitions through the same rifle using the Govnah by having it set to the 'adverse' setting. No buffer swapping. No remembering how many revolutions to turn a set screw. Just push the regulator plate and done.
So from LE/Military perspective, they typically don't run cheap ammo and the ammo is a known variable. They are not going to be using Simunitions or some weaker powered frangible training ammo in the field. They will be running full powered ammo in the field and in the event they need more gas, it will be a simple matter of moving the regulator plate with no tools. Why not run full gas all the time? Well, when talking about short barrels it is a big difference the article mentioned above in Recoil had a 11.5" barrel that ran all day with brass at .063 but came from the factory at .073. .063 is what you'd normally see in a 16" carbine. It is noticeably smoother running at .063 and along with that is less fouling to the action when running optimal gas. But as long as you have a bullet going down a bore you will get fouling (this includes a piston system). So running optimal gas extends the amount of rounds you can put down range before it is time to clean it and if you don't have time then you can crank it up to the adverse setting to get you through it.
From a recreational shooter perspective, you now have the ability to shoot the cheaper surplus steel cased stuff - OPTIMALLY and shoot the SHTF stuff OPTIMALLY as well. When I say optimal, I'm not talking about just the reduced recoil but again the reduction of fouling into the action. Something no buffer can reduce - only controlling the gas will do that. H2 buffer is all that is required to stop bolt bounce in full auto and it has been used in the M4 for a long time and I have yet to hear about one failing. Going heavier is more reciprocating mass.
Plenty more video and info on my site:
http://micromoa.com Feel free to contact me if you have any questions.
Thanks!
