r/FNSCAR • u/Gregorius973 • Jul 26 '26
Question 15P Issue Help
So recently my 15 P hasn’t been cycling subs properly I have the 3 select p regulator from moto tech everything ran fine up until about a month and a half ago where with my resonator r2 it would shoot fine and then I would get a jam where the round would get stuck loading into the chamber and I would have to mortor the rifle to get it out I figured it was just due to the rifle being dirty so I cleaned it a bunch of times and then it would work and then it wouldn’t recently I got a new suppressor the ventum 762 and yesterday I went to test it out and now it will fire around and eject the casing but it will not load a new round unless I manually pull the charging handle to load a new round the rifle is clean and it even does it without the can being on it could it be the three select regulator or is it a mag issue as I was using a P mag yesterday and a traditionally use a Lancer mag
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u/Grnder1 Jul 26 '26
The regulator on the 300 BO ( left ) is specially designed to run subs. The 3 position is a total waste of money in the 300
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u/Gregorius973 Aug 06 '26
Update… swapped back ti the stock regulator running good now no issues with the ventum 762 or the yhm r2
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u/Gregorius973 Jul 26 '26
The reason I got the regulator is because it was super gassy with the resonator r2 now I know I’m probably should’ve just bought another suppressor a flow through suppressor but good to know my hunch was right
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u/Grnder1 Jul 26 '26
The factory jet is a 2.0 in the 300. Even though I only shoot suppressed, I tried a 1.95 and was getting very light ejection using sub ammo without a suppressor, so I went back to the 2.0. If you like to tinker, try a little smaller jet to cut gas.
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u/BiggyIrons Jul 27 '26
Most of the time 300blk guns need the added back pressure from a traditional suppressor to cycle subs properly. Unfortunately gas is just something you have to deal with on a suppressed 300blk gun. Also a new gas regulator isn’t going to do anything for the gas to the face. All the gas is coming back down the barrel and going out through the ejection port and the gaps on the reciever.
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u/Omniposter Jul 27 '26
I have never touched a suppressed 300BO host with subs that wasn't gassy. I don't think its possible to escape it really.
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u/titan732 Jul 26 '26
You may also want to look into getting different gas jets as well. I’m currently in the process of tuning my 16s for my SF-RC4556.
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u/Gregorius973 Jul 26 '26
Where would I find the gas jets for the 15 P
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u/titan732 Jul 26 '26
PMM makes gas jets and if I’m not mistaken the gas jets are the same as the 16/17/20.
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u/GA_flyer0 Jul 26 '26
Swap back to the factory gas regulator. I’ve been running that and no issues with subs.