I think I have solved my over gassing problem. I've been fighting this ever since I got my RFB. After getting it back from Kel-tec with new gas and barrel everything except Prefecta and American Eagle .308 150 gn was over gassed. All 7.62 were over gassed. Talked to Kel-tec and tech told me that I should be in the B+8 range for 7.62. I was over gassed with cap almost off. Piston was still very tight after many trips to range. I removed the 3 gas rings on piston. Now all 308's and 7.62's are in the B+7 to 10 range. Now I'll try my suppressor and see how it works. Before I was B+25 with .308 and now around B+9. Still think it will be over gassed at B+ 40, but it's worth a try.
Fixed my over gasing problem
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I have 250 rounds through mine and I can take the gas knob completely off and the bolt will lock back on any ammo I try. I have the knob set at B+41 just so I won't lose the cap. I lined the gaps in the three gas rings up thinking it may bleed off more gas but I have not tried it yet.
I think I will remove the gas rings completely as you have and see if I can get it to lock back in the B+5 to B+25 range. That will certainly prolong the life of the buffer, bolt, etc.
ronmar, why do you think they changed that gas ring design?
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Which time? 
The first time was when they went from the 1st gen piston to the 2nd gen. The 2nd gen piston is WAY easier to machine. I guess they thought they could get fancy and do away with the pistons and use the machined discs of the new design to provide enough resistance and gas bypass.
One thing I have noted since the 2nd gen came out is a little less consistent gas system performance and the seemingly endless string of folks who had issues adjusting the gas system per the manual. Also note the several different 2nd gen piston designs that have emerged, I am assuming to attempt to control this issue. Now it appears that the rings have been re-introduced on the 2nd gen piston(yet another variant) in a similar attempt.
The first time was when they went from the 1st gen piston to the 2nd gen. The 2nd gen piston is WAY easier to machine. I guess they thought they could get fancy and do away with the pistons and use the machined discs of the new design to provide enough resistance and gas bypass.
One thing I have noted since the 2nd gen came out is a little less consistent gas system performance and the seemingly endless string of folks who had issues adjusting the gas system per the manual. Also note the several different 2nd gen piston designs that have emerged, I am assuming to attempt to control this issue. Now it appears that the rings have been re-introduced on the 2nd gen piston(yet another variant) in a similar attempt.
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Correct on both. The first and second gen gas pistons are completely different and NOT interchangeable. Post a pic of your piston so we can be sure on that if you like. The biggest giveaway is that you have to rotate the 1st gen piston about 30 degrees to unlock it from the gas block. The second gen just pulls right out after the carrier is removed...
The rings used on the first gen are from the AR gas system, so anyone who has AR parts(probably just about every gunsmith in the US) should have replacements for you, should you need them...
Everyone keeps mentioning "rings" but I just took the darned thing off, and there was only ONE ring!?!
It was a yuuuge ***** to remove too!
So since I could't remove only one or two, I took the single triple wound ring off. I am going to have a hell of a time putting it on. I'll see if standard AR-15 rings will go on.
As far as the piston, yes it came out with a rotation, but it was a 60 degree twist, as per my manual.
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So I guess I see what results I get suppressed with zero rings and a reinstalled adjustment knob.
Is that too much porting I wonder?
Even with a can?
It was a yuuuge ***** to remove too!
So since I could't remove only one or two, I took the single triple wound ring off. I am going to have a hell of a time putting it on. I'll see if standard AR-15 rings will go on.
As far as the piston, yes it came out with a rotation, but it was a 60 degree twist, as per my manual.
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So I guess I see what results I get suppressed with zero rings and a reinstalled adjustment knob.
Is that too much porting I wonder?
Even with a can?
Removed the SINGLE gas ring (really long). Fired gun with no gas rings at all.
Locked the bolt with suppressor on with minimal gas setting.
Would not lock it with suppressor off even fully maxed setting.
Gotta install 1 or 2 rings and retry. Looks like I will be overgassing to some degree, but I can't have it both ways, apparently.
Locked the bolt with suppressor on with minimal gas setting.
Would not lock it with suppressor off even fully maxed setting.
Gotta install 1 or 2 rings and retry. Looks like I will be overgassing to some degree, but I can't have it both ways, apparently.
Now that's interesting.
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Purchased directly from the factory? Or from a dealer/FFL or online?
It makes a difference, it may have been made months (or years) ago...sitting on a shelf somewhere.
texcl2, that serial is newer than mine and I have one of the Gen 2's with no rings. Could you post a pic of the piston so we can get a look? There are quiet a few people here that have been helping trouble shoot gas issues (I have benefited from many of them) and if there is a new piston out in the wild that will make things much more interesting... I mean complex... for diagnosing problems.
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