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Turning down the Gas on an AR gains more Velocity behind the bullet?


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Hi Eveyone

Ok so i figured out that my 8" SBR in 338fed was over gassed..and i turned the gas selector 3/4 way to the close position and now my AR10 is shooting much smoother and kicking the brass at a 4 oclock direction..I did another chronograph test after i did this and i am gaining about 100fps faster at 2310fps out of my barrel using the same 185gr American Eagle. The weather today was cooler than before ..temps were around 87F. Any thoughts? I made a video to record the results from today but i have not yet uploaded it..

 

 

 

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Tune your gun to run, good ejection pattern and no FTF's or FTE is more important than velocity of projectiles .

Never really had any failure to eject or feeding problems with it since i built it..but if yo take a look at this video ..I am ejecting brass in the 1 oclock direction showing an indication of the gun being overgassed.. After turning the gas down 3/4 way to close ..I am now ejecting Brass at a 4 oclock direction which is perfect and the gun is not over gassed.. But i discovered while doing this my bullet velocity increased to about 100fps faster than my previous testing..

 

Edited by jeanclaudesegal
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 The theory is sound , but far too many variables to say for sure that ,that's why the increase in Velocity . I find it odd that you can get that velocity increase from an 8" bbl., a longer barrel maybe ,just  maybe .

I dunno..But you saw both videos from my previous testing ...one with the gas port opened almost all the way and the other 3/4 way closed..and the velocity results were different ..Im not too sure about the whole sound thing

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On the day you got that video, it would have been very beneficial to shoot the gasport wide open, and again 3/4 closed, and compared those results.  Instead, your comparing data from different shooting days, and those days have different weather data. 

 

"The theory is sound."

 

I dunno..But you saw both videos from my previous testing ...one with the gas port opened almost all the way and the other 3/4 way closed..and the velocity results were different ..Im not too sure about the whole sound thing

I'm not sure you understood what he's saying - he's not saying that sound is the theory...  he's telling you that your theory of closing the gasport seems solid...

Edited by 98Z5V
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On the day you got that video, it would have been very beneficial to shoot the gasport wide open, and again 3/4 closed, and compared those results.  Instead, your comparing data from different shooting days, and those days have different weather data. 

 

I'm not sure you understood what he's saying - he's not saying that sound is the theory...  he's telling you that your theory of closing the gasport seems solid...

whoops.. my bad ..lol ..Weather was a factor. but this time it was cooler ..

Edited by jeanclaudesegal
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