Semi-SASS Build

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14 years 5 months ago #4804 by Engineer
Semi-SASS Build was created by Engineer
My parts are here, now to get the tools I need. This rifle is an AR-10T lower with the Mag Pul PRS stock, and a new U10TBF upper. I also have the SASS gas system and quad rail. Currently it has a 3.5 x 10 Leupold Vari-X III in an ArmaLite 1" mount and an A.R.M.S. quick release adapter. I have the Harris Bipod and mount adapter on order along with the adapter and switch for the Streamlight TLR-1.

Questions:

The SASS gas system is two position, suppressed or without. I didn't want to do anything to reduce the accuracy of the target barrel, so don't plan to thread the (T) barrel, and think that drilling the .099 hole might also reduce accuracy. Should I leave the (T) gas system alone, and just add the quad rail?

Is there a sling that can stay connected to the butt stock, and yet be wrapped around the upper left arm? This would be a carry sling, but with a separate cuff for the left arm. Adjusted properly it would go from the butt stock across the chest to the cuff on the upper left arm and to the fore end.


All comments appreciated

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14 years 5 months ago #4809 by a Guest
Replied by a Guest on topic Re:Semi-SASS Build
The gas port hole needs to be .093 but larger or smaller wont effect accuracy. These rifles aint as squirley as others because of the gas sustem but that will change with the pain in the gas piston systems.
The 6.5 Grindel runs a .112 to .116 gas hole with .116 being max for all as the gas tube hole is only .116. Usually CARs use a .062 with mid length using a .080 and rifles using .093 holes as a STD. These are being over gased on these sizes. Need to look at the ammo to barrel length relation because 19500PSI is what is needed to cycle the action. Different ammo at different barrel lengths produce a wide range of PSI. If you drill the gas hole you need to drill it burrless.MSH

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14 years 5 months ago #4816 by mrraley
Replied by mrraley on topic Re:Semi-SASS Build
Engineer wrote:

Questions:

The SASS gas system is two position, suppressed or without. I didn't want to do anything to reduce the accuracy of the target barrel, so don't plan to thread the (T) barrel, and think that drilling the .099 hole might also reduce accuracy. Should I leave the (T) gas system alone, and just add the quad rail?

Is there a sling that can stay connected to the butt stock, and yet be wrapped around the upper left arm? This would be a carry sling, but with a separate cuff for the left arm. Adjusted properly it would go from the butt stock across the chest to the cuff on the upper left arm and to the fore end.


All comments appreciated


Just a suguestion... but if your not going to thread the barrel to put a suppressor on it, change the adjustable gas block to a plain gas block.

As for your sling. Are you looking for a leather sling or nylon web?

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14 years 5 months ago #4819 by Engineer
Replied by Engineer on topic Re:Semi-SASS Build
I would prefer a web/nylon sling. I have a leather sling on an old Model 70 target rifle, complete with rail, it was cobbled up by an old friend in the 50s when he was shooting competitively. It is similar to what I am describing, with an extra loop, one for carrying, one for the loop around the left arm. You wrap the sling around the arm, and after a few minutes it starts to make your left hand get numb. I am thinking either nylon or a separate cuff would do a better job.

The upper has the standard gas block now. To install the SASS gas block I would have to drill out the gas port to .099 inches and to make it useful I would have to thread the end of the barrel and add a suppressor. I didn't read closely enough to find that it is a two port system. I had the idea that it was adjustable from standard down to the flow needed for a suppressor. That way I could tune the gas system to the load.

Thanks,
Barry

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14 years 5 months ago #4820 by Engineer
Replied by Engineer on topic Re:Semi-SASS Build
I can put it on the mill and run the drills up in steps of a few thousandths at a time. I can also feed at low speed. I have met some stainless that tears instead of cuts. I think you mentioned that converting the SASS gas block to a variable block is possible. By not reading very carefully, I thought the SASS gas system was adjustable from normal to suppressed, so I could adjust the gas block to fit the ammo. It wasn't until I was looking it over that I realized it was a 2 position block.

I was looking at the amount of circumference that the recommended .099" hole would take out of a barrel with the .300/.308 inch diameter. I guess you are right, on the 6.5 and .223 the gas port is proportionally larger.

Thanks,
Barry

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14 years 4 months ago #4853 by rmh996
Replied by rmh996 on topic Re:Semi-SASS Build
The SASS gas system is for the installation of a suppressor. Not all suppressors have been tested by Armalite. This is why they specify to start with a specific size hole mod and then test with the suppressor. You look for about a 35 degree ejection angle. How, don't know the best way, but I video taped from above and played back in slow motion. We put a large sheet of white cardboard down on the bench with Sharpie lines drawn on it at various angles. Put the weapon in a mount on top of the cardboard, mount the video above that and fired it.

Anyway, I found an alternate method using a variable set screw type of gas tube. This allows you to fine tune it.

The suppressor, if you are interested is: www.yankeehillmachine.com/store/phantom762.html . The QD allowed me to mount this same suppressor on a Ruger 10-22 and an AR-15. As long as the calibre is less than .308, it will suppress it.

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14 years 4 months ago #4989 by Engineer
Replied by Engineer on topic Re:Semi-SASS Build
I would like any information on making a setscrew variable gas block. Particularly the size of the setscrew and material. I am guessing the setscrew hole is drilled from the action end of a standard gas block. I am also guessing that I need to drill out the barrel port to either M093 or .099 Tmmsshh recommended .093, ArmaLite .099. I have the two position gas block and tube from the SASS gas package.

Thanks,
Barry

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14 years 1 month ago #5769 by Engineer
Replied by Engineer on topic Re:Semi-SASS Build
Finally, I have two rifles to try out. The older AR-10T has the original 24" Armalite barrel and gas system. The upper action and bolt carrier have been replaced by new parts with forward assist. The fore end is a quad rail from Armalite. This one has a simple sling with Quick release front swivel. The lower is a new Armalite with A2 butt stock and about 30 minutes worth of tripper work. The scope is a Nikon 6 x 18 x 42 with mil-dot. The second rifle is a current AR-10T with Mag Pul PRS butt stock The fore end is a quad rail from the Super SASS. The scope is a Leupokd 3.5 x 10 x 40 MK---There is a Streamlight TLR-1 flashlight with rail adapter and external switch adapter, a Harris S-LM bipod and ARMS adapter to rail. The sling is a nylon Ching Sling. It is a bit disappointing. The overall length is a bit short for the barrel down optics forward carry. The sling swivels take about 30 turns to loosen them and are plastic. The current set up is front attachment to bipod, rear of forend with MI rail to stud adapter and around the rear loop on the butt stock. It does help in prone, sitting, or kneeling position. It should be made so that you don't have to cut the Quake swivels or unsew the tabs to remove them. A QC front swivel would allow quick detachment of the bipod. I will probably get another sling and rebuild the two to give a QC at front and a little more OAL. Scope mounts are ARMS 30mm rings and bushings on one and an Armalite 1" mount with an ARMS quick release adapter plate.

In a few months I hope to upgrade the scope on one of them and add the night vision capability. The ATN P22 looks like a good deal. One of my friends has one and will loan it to me for hog hunting when I can get free to shoot hogs.

I will try to get some pictures. Before the 2nd quad rail, I had thought I was going to use the tubular front end with rail inserts. I have a new barrel nut and forend ring, a like new tubular forend and 3 unopened 5" rail sections for botton and sides or top and one side. If anyone is looking to convert to a free floating fore end. I also plan to add another PRS butt stock to replace the A-2 butt stock.

Thanks,
Barry

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14 years 1 month ago #5801 by Hot Lead Zapper
Replied by Hot Lead Zapper on topic Re:Semi-SASS Build
EDM, Electrical Discharge Machining

EDM Drilling would be the best method for burrless .099 port.

production-edm.com/node/20

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