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Posted: 5/31/2026 10:03:20 AM EDT
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I just put a surefire rc2 on my OG scar 17. I've read about swapping the gas jets until its cycling reliably, but I don't mind the gun being a little over gassed for reliability. With the rc2, and the gas block in the suppressor setting, cycling was fine, and ejection was around 4:00. I'm wondering if I'm significantly damaging anything by just leaving it factory. The rc2 being so low back pressure, maybe it's not that big of a deal to re-gas? |
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since you say cycling & ejection are good, you should be fine. i only tuned mine to help scope last longer  if you do tune, the other thing to be mindful of is: bolt locks back on empty mag |
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Tennessee Squire
#PlasticPoniesForAll
Aimless = Suburban Pot Bellied Snow Chicken
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I'm not up on it, but I think lot of people have gone to third-party adjustable regulators (KNS Discarder, Mototech SCARburator) to avoid the need to remove, replace or tune w/ the OEM gas jets. The folks over at the FN Forum, SCAR sub-forums will have everything you need to know about what is out there these days. |
"Bitter clinger since 7 years old. Now a full-time deplorable and garbage person."
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The RC2 is on the lower back pressure end on Pew's back pressure chart here. His chart has it down near the OCL Infinity when it's vented. If recoil isn't bad and ejection isn't overly violent you might be good to go just using the suppressed setting. If you do want to make a change I did end up putting the KNS Discarder in one of my 17s and a 20. I found it easy to adjust and it comes with additional gas plug sizes for even more adjustment. |
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Originally Posted By stevelish: KNS is the answer. I get that, but even once you have a kns, and you start tuning from the bottom end of reliability, how much above "cycling reliably" can you go? I read plenty about how to work your way up from nothing, but I'm not certain I actually have to spend $300 when everything is cycling fine. I know it's overgassed from the start, but if it's not obvious I'm breaking anything, I think I'd prefer to just leave it factory. |
It’s long but it’s though  PMM SCAR GASJET VIDEO Spoiler alert: for your 17 with a 16” barrel just get a 1.4 and call it good. Factory is over gassed even un-suppressed so I don’t see why you wouldn’t want to tune it. Gas jets are like $8-10. |
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Here’s how I did mine, albeit a Scar 16, but I’d do it the same way if I had a 17… Tuning my Scar 16 thread with pics |
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Originally Posted By SteveJobs: I get that, but even once you have a kns, and you start tuning from the bottom end of reliability, how much above "cycling reliably" can you go? I read plenty about how to work your way up from nothing, but I'm not certain I actually have to spend $300 when everything is cycling fine. I know it's overgassed from the start, but if it's not obvious I'm breaking anything, I think I'd prefer to just leave it factory. Originally Posted By SteveJobs: Originally Posted By stevelish: KNS is the answer. I get that, but even once you have a kns, and you start tuning from the bottom end of reliability, how much above "cycling reliably" can you go? I read plenty about how to work your way up from nothing, but I'm not certain I actually have to spend $300 when everything is cycling fine. I know it's overgassed from the start, but if it's not obvious I'm breaking anything, I think I'd prefer to just leave it factory. Turn it down until it doesn't hold open on an empty mag. Turn back up at least one click, two if you just want to be sure. Kns makes it really.....really easy. You can custom tune to different suppressors, different ammo, different weather conditions, etc.........with the turn of a knob. Worth it to me, YMMV. |
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KNS is what you seek https://knsprecisioninc.com/product/discarder-for-the-fn-scar/ |
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Originally Posted By SteveJobs: I just put a surefire rc2 on my OG scar 17. I've read about swapping the gas jets until its cycling reliably, but I don't mind the gun being a little over gassed for reliability. With the rc2, and the gas block in the suppressor setting, cycling was fine, and ejection was around 4:00. I'm wondering if I'm significantly damaging anything by just leaving it factory. The rc2 being so low back pressure, maybe it's not that big of a deal to re-gas? I have the same set up. I run a Surefire 762 on my Belgian 2012 mfg SCAR 17. No need to change the gas jet. For the higher back pressure cans, yes. |
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You're likely fine. I purchased my 17s with a scarburator and enhanced buffer pad installed already by the previous owner. I did upgraded torx receiver screws myself. I'm very anti-adjustable gas on any firearm, but I feel better that those parts should hopefully increase longevity. Set the gas on the first range trip. Haven't touched since, so we'll see if it gives me issues after a few more thousand. Full size RC2 on a 14.5 with approx 1k rounds shot. |
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