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Discussion Starter #1
My question is since this is my first SCAR, why the heck is there so much lost pressure and powder burns all over the front sight, and the front of the rifle? I mean in slow motion videos the flash that is coming out of the gas regulator switch is as bright as the end of the muzzle break or compensator. Why?? I don't see that happen on any other rifles I own like this one. It doesn't happen with my ACR .556 or with it's 300 Blackout bbl. Has anyone else seen the front of there rifle turning red with powder residue? It's a pain in the @$$ to have to take the forend extension off each time and clean this thing. I like my firearms clean as new and ready to go. I'm hoping this is not a normal issue with SCAR 17's. Thanks for your help and feedback!!!! .5 Picture 065.jpg .6 crop Picture 015.jpg
 

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It's not red. It's actually vaporized copper from your projectiles and it occurs with every center-fire rifle. It's just more noticed on weapons which vent excess gases onto their blackened components surfaces.

If your ACR has a muzzle attachment, you'll find copper deposited on it also.

-SS
 

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Discussion Starter #3
I understand the vaporizing copper, but the color changes with changing powder or purchased ammo. The ACR has and adjustable gas system and the AAC threaded brake for my can and it doesn't leak a speck. There is a different "leaking" issue here. Flames should not come out of a gas adjuster unless it was engineered that way. That's what I'm trying to find out is all of these SCAR vent out all over the front of the rifle. Thanks!
It's not red. It's actually vaporized copper from your projectiles and it occurs with every center-fire rifle. It's just more noticed on weapons which vent excess gases onto their blackened components surfaces.

If your ACR has a muzzle attachment, you'll find copper deposited on it also.

-SS
 

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Discussion Starter #4
Here is a photo of the very similar gas regulator system on my ACR next to the SCAR showing how similar they are. The ACR doesn't leak or get dirty at the regulator at all. .5 Picture 001.jpg
It's not red. It's actually vaporized copper from your projectiles and it occurs with every center-fire rifle. It's just more noticed on weapons which vent excess gases onto their blackened components surfaces.

If your ACR has a muzzle attachment, you'll find copper deposited on it also.

-SS
 

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Reason you see flame coming out is, as with the muzzle there is unburnt powder coming out, and burning. This is normal. The FS2000, 5.56 weapon, also does this. And I am guessing the SCAR 16 as well.
 

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The piston expels all of this stuff.. That's why!
 

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Every gas op semi auto vents gases. If not you'll have pressure spikes and premature wear. Depending on the make and manufacture of the weapon, they will be different on how they vent. Ammo manufacturers will burn cleaner or dirtier depending on what powders and primers is used. Don't forget about the exposed lead in bullets after they're fired will leave residue.
 

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If I recall, red is typically a lead oxide color. You might try some HPBT loads and see if that at least changes the color of the deposit. FMJ leave lead exposed at the tail of the bullet.

It won't solve your venting problem, but it could turn your deposits from red to green. :)
 

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I hear what you're saying, but I'm not sure my scar does what you are saying. Here is a thermal image of me shooting, and there is only a little gas escaping the gas regulator switch, not a ball of fire like you describe.
ThermalShoot2M.jpg
 
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Discussion Starter #11
LOL!!! So nice of you to chip in with the shipping! :thanksrp8: But I think I'll hold onto it and the Leupold Mark 6 3-18x44 with the Horus 58 reticle and it's Mark 6 mount. It truly is my favorite scope I own for this platform. (and I own more scopes than you would ever believe. Seriously!
Your 17 and scope is defective. I'll gladly dispose of it and play for you to ship it to me.
 

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I just can't figure out why there is nothing, not a spec of gas leaking out the ACR's gas adjustor. And that's when it is set in either suppressed our unsuppressed mode. I hate the fact it's losing pressure like this. Talk about inconsistent pressure curves and big ES and SD on velocity numbers on the Oehler 5 Ballistic Chronograph. Same match ammo in 2 different other rifles (bolt gun and a LaRue) so ES in this match Lapua ammo at only 12fps.!! Out of my SCAR.... over 62fps. :|
I hear what you're saying, but I'm not sure my scar does what you are saying. Here is a thermal image of me shooting, and there is only a little gas escaping the gas regulator switch, not a ball of fire like you describe.
View attachment 22335
 

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Oopps! That's a Model 85 not 5 for a model # of the Oehler. Type O - and it wouldn't let me edit it. Sorry!
 

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I hate to ask this, please don't take offense. Is your gas regulator assembled and set correctly? If you were running it on suppressed mode I could understand more of a discharge. Or if something wasn't tight. I'll chrono some more rounds next time I'm out, but I don't remember having a huge deviation.
 

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I just can't figure out why there is nothing, not a spec of gas leaking out the ACR's gas adjustor. And that's when it is set in either suppressed our unsuppressed mode. I hate the fact it's losing pressure like this. Talk about inconsistent pressure curves and big ES and SD on velocity numbers on the Oehler 5 Ballistic Chronograph. Same match ammo in 2 different other rifles (bolt gun and a LaRue) so ES in this match Lapua ammo at only 12fps.!! Out of my SCAR.... over 62fps. :|
I am certainly no expert, but both of my ACRs show evidence of gas venting from the regulator area based upon some carbon build up I see on the top of the barrel just below the regulator. I think the ACR's regulator vents out the bottom whereas the SCARs vent directly forward. Again, this is just my observation.
 

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Discussion Starter #16
Thank you for your replies and I truly take no offense - the gas assembly is correct and set to the 12 O'clock position (un-suppressed) Here is some photos of my wife shooting it and you can see the pressure loss even in broad daylight. Closer to night it is really apparent. Picture 018.png Picture 020.jpg Picture 022.jpg Picture 023.jpg
I hate to ask this, please don't take offense. Is your gas regulator assembled and set correctly? If you were running it on suppressed mode I could understand more of a discharge. Or if something wasn't tight. I'll chrono some more rounds next time I'm out, but I don't remember having a huge deviation.
 

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Discussion Starter #17
That last photo is showing the hot burning powder escaping at the regulator, and that is purely lost pressure that should be being used for forward velocity and down range energy. What a sad waste of powder / power.
 

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Discussion Starter #18
Here is a photo of my wife shooting the ACR with 60+ round through it and the bbl at the gas regulator as I stated is spotless and nothing at all to clean up. No loss of pressure. 1 crop 1 IMG_0645.jpg
 

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Have you removed the gas regulator & cleaned out including the piston inside area? Mine was pretty carboned up even when new. Maybe yours is not seated properly allowing the some of the pressure to take the path of least resistance?


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No safety glasses shooting the ACR?

Also the ACR is 5.56, less powder volume compared to the .308 out of the SCAR. You are comparing apples, to oranges.

What Brand .308 ammo you using?

The bullet has left the barrel, as evident by the muzzle flash. The lost velocity you are talking about from the "wasted" gases is so small. IF you were to plug it up so nothing escaped, you would not see a difference, except that it would no longer be semi-auto.

You are really splitting hairs here.

Every semi-auto gas driven gun, via piston or DI. is "losing" pressure, because pressure is used to work the action.
 
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