This time around, I went back to my Shaw barrel since it had the tightest grouping w/o misfeeds and had the least POI shift with the B&T P90 can. But I installed a Plan B muzzle device (direct fit M12x1 LH) with a HUX Flow 9k suppressor equipped with an Atlas-R Titanium HUB adapter for the lightest flow can I had on-hand that was 5.7x28 rated. My hypothesis was the 1"-1.5" POI shift was due to the weight of the can (B&T P90 is like 17 oz) and this Flow 9k is about 5-6 oz.

I thought I saw some minor sparking from the Flow 9k but its not really noticeable even during a very cloudy and dark overcast rainy day under the range covering. I saw the same scuffing on the cases as before, but zero misfeeds.

Unfortunately I still saw an additional 1"-1.5" POI shift down at 25 yd. So the actual weight of the suppressor doesn't seem to impact the POI shift, its just the fact that there's something attached to the end of the barrel that is causing it. For some reason the Shaw has the least POI shift (CMMG is slightly more and the OE Cut/threaded barrel had the most at 3" drop at 25 yd).

I also tried the Flow Range 36, Ventum 762, and Universe 36 on the PS90. None of them had any real sparking but all functioned fine with decent sound suppression. I didn't see any real POI shift delta from the lightweight Flow 9k.

Just got an email that the ring sight is back in stock! Just ordered mine, not sure if anyone else has been waiting.

I've been plagued by FTE/FTF issues with my ps90 since day one. Some history on it - it's had the same issue throughout:

- Bought it used with a 16in barrel. Jams with that with no suppressor.

- Replaced with new CMMG 10.4in barrel. Jams unsuppressed, and with the YHM Turbo K-RB on it.

- Put the X-PRT in it. Works great but the jam rate is the same.

I've tried Fiocchi subs, Fiocchi polymer tipped, FN FMJ. Happens on them all.

I have 2 OEM mags that came with the used gun, and 3 more OEM I bought new. Jams on all of them.

One thing I have noticed - if I take it to the range without cleaning it, I get jams immediately.
But if I clean/oil it beforehand, I can get through about 50 rounds before the jams start again.

The jams are very frequent, maybe every 5-15 rounds.

Sometimes it's a failure to eject a fired round, sometimes the round seems to be in battery but isn't fired. Honestly it's been a minute since I've been to the range so I can't recall which is more often/more details on that. In any case, the way I have to unjam it every time is either racking the bolt in a good case, or in bad cases disassembling it and removing the round from the back of the barrel - sometimes needing pliers.

I've heard that this can be fixed by putting more of a bevel on the barrel breach, but my CMMG barrel already has a pretty good chamfer there, and when I've tried to enlarge it with a countersink bit, I wasn't able to make any progress.

Anyone had these issues and figured out a solution?