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Posted: 4/14/2010 10:57:45 AM EDT

I am building a SASS/M110/SPR clone based around a Krieger M110 service rifle barrel that they are making for me. (20 inch barrel) I have a few questions about suppressors and the gas system. I will be shooting this rifle both suppressed and non-supressed with a QD Mount.

Do I need a variable gas system for my rifle?  The gas port is already drilled at .093

Can someone recommend me a variable gas system for my rifle if I need one?

Is it really necessary to throttle the system down for reliable function?

Looks like the Armalite system will work. Is this a good system? Are there other options?

Thanks in advance

Link Posted: 4/14/2010 12:54:57 PM EDT
[#1]
.093" is on the large side for the gas port.  My custom Krieger 20" barrel port was cut at .082", and the rifle would not function until I opened the port up to .086" (using the Armalite length gas system).    You may have exaction problems with some ammunition right now without the suppressor.  

I would personally use an adjustable gas block for your application.
Link Posted: 4/14/2010 3:27:31 PM EDT
[#2]
That's interesting.  Is this suppressed or unsupressed, the .086?  Armalite opens their gas ports on the SASS up to .099 with their adjustable gas block system.  They even say that this is bigger than that port on the AR-10T.

"The AR-10T’s gas port is smaller than the gas port on the Super SASS. So, you’ll need to drill out the barrel’s gas port. For the standard S SASS barrel the appropriate gas port diameter is 0.099 inches. assembling the rifle, and testing for function. Appropriate gas port diameter is achieved when the rifle cycles reliably without excessive ejection force."

Installing a sound suppressor on any semiautomatic (or automatic) firearm will significantly increase the cyclic rate of the firearm. The increased cyclic rate will increase stresses on rifle components and may result in an increased rate of malfunctions and/or parts breakage. ArmaLite’s® Selective Gas System allows the user to reduce the gas flow to the weapon system when a sound suppressor is being employed, thereby reducing the cyclic rate of the rifle.


Do they do this because they want to over compensate and make sure they have enough gas to reduce with the adjustable system?

I think I am going to go with what I have with a standard gas system and the current size port of .093 and see how it shoots unsuppressed first.  Then add the suppressor and see if I need to install the adjustable system.  I want to be able to shoot both suppressed and unsuppressed with reliable function for both situations.
Link Posted: 4/15/2010 1:17:08 PM EDT
[#3]
.086" is unsuppressed.  

You will probably be ok, but the adjustable block doesn't add all that much to the cost, so why not get one?
Link Posted: 4/16/2010 2:32:12 PM EDT
[#4]
The problem isn't that I don't want to get one, it's that I don't want to use Armalite's rails.  And their gas system is only compatible with their rails.  I really want to use PRI rails instead with the top rail.  And there is no other manufacturer that makes and adjustable gas system for a .875 barrel.


Link Posted: 4/18/2010 12:17:12 PM EDT
[#5]
These are the dudes I was looking to make me a custom adjustable gas block.  they can do LOTS of different versions...just ask em a question.

bottom of this page
http://teppojutsu.com



Link Posted: 4/18/2010 10:48:43 PM EDT
[#6]
Pallidin Machine Adj Gas Blocks  $60

How much are the teppo jitsu blocks?
Link Posted: 4/19/2010 1:12:42 AM EDT
[#7]
I just want this in .625, .875, .936 as well as the .750 they offer.
Link Posted: 4/19/2010 8:01:42 AM EDT
[#8]


that is more of an option to mitigate an overgassed gun, not really for switching back & forth b/t suppressed & non suppressed.

The pallidin machine guy can make the gas blocks in .625 ID too
Link Posted: 4/19/2010 8:13:13 AM EDT
[#9]
I posted this on your other thread in the AR10 section but I'll copy it here too:

I had a Palladin adjustable gas block on my 20" Armalite standard profile barrel and it was not working as well as I had hoped.

No slight to the Palladin, I just don't think it was necessary and was causing some cycling issues.

The bolt would not always lock back with the block open to full and shooting unsuppressed and the same for being partially opened while running suppressed.

The switch would also get harder to turn as the carbon built up but that is typical of any switchable gas block.

I removed the 20" barrel and I am putting the Palladin on my 300 Whisper build where it would be better suited.

I bought a Noveske 18" for the AR10 with the gas port in the carbine position and it works great for both suppressed and unsuppressed for all my reloads so far.

I am also thinking of getting a Slash heavy buffer but damn they are expensive, but I am sure they are awesome.
Link Posted: 4/19/2010 1:04:39 PM EDT
[#10]
Quoted:
I posted this on your other thread in the AR10 section but I'll copy it here too:

I had a Palladin adjustable gas block on my 20" Armalite standard profile barrel and it was not working as well as I had hoped.

No slight to the Palladin, I just don't think it was necessary and was causing some cycling issues.

The bolt would not always lock back with the block open to full and shooting unsuppressed and the same for being partially opened while running suppressed.

The switch would also get harder to turn as the carbon built up but that is typical of any switchable gas block.

I removed the 20" barrel and I am putting the Palladin on my 300 Whisper build where it would be better suited.

I bought a Noveske 18" for the AR10 with the gas port in the carbine position and it works great for both suppressed and unsuppressed for all my reloads so far.

I am also thinking of getting a Slash heavy buffer but damn they are expensive, but I am sure they are awesome.


So, you want to put an AR15 receiver extension & telestock on your 18" noveskie barreled AR10?  

There are a lot a variables when a guy is sending out a part for others to put on their franken rifles.  He has some guidelines of how to size the suppressed port relative to barrel length, gas port size & location, but it is hard to account for so many potential variables.  I wonder if he or somone else could open your suppressed setting up a little bit?  

Tell me, can you disassemble that gas block to clean the carbon, or soak it to loosen it up?
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