Mags *finally* available. I've linked the 3-pack bundle here but they have singles as well.
Mine had free shipping when I ordered the bundle.
Currently shows 179 in stock.
Finally got some time to shoot again today and put a few hundred rounds downrange.
My initial function test of 115 Federal Champion went pretty poorly, essentially having the exact same experience as Honest Outlaw.
This time went better. Sort of.
Ammo I tried today:
Winchester 124gr NATO
Blazer Brass 147gr
Federal Champion 115gr (again)
Freedom Hush 165gr.
I forgot my Syntech 150 and HSL 147, but judging by the results that follow, I don't think it mattered.
So, having done a break-in on my Mac 5 with 124 NATO, I suspected I might have to do the same with the RPC. But first, I disassembled everything, cleaned, and lubed it up fresh. Also installed a trilug muzzle device so I could run with a YHM R9 after I break it in.
Ran a mag of the 124 NATO. Worked great. Good start. Continued to do that for 150 rounds with no issues. Grabbed the R9 and installed it and ran the next 100 rounds of 124 NATO suppressed with the 110* locking piece. That also went great. Brass was pretty consistently ejecting about 10 feet away with and without the suppressor.
Took off the suppressor and grabbed the 115gr Federal again to see if anything had improved. Nope. Same issues as before. Hmm.
Put the R9 back on and thought "well it should run with the can". Nope. Fewer FTE--maybe get 5-10 max rounds or so at best before FTE. Super weak ejection when it did eject.
Switched to Blazer Brass 147. Same issues. Uh oh.
For the lulz, I loaded up 10 rounds of Freedom Hush 165. This stuff runs fine in my Mac 5. Not here--same issues as everything besides the 124 NATO. To be fair, this stuff is on the ragged edge for some guns if you overtune so I didn't expect it to work here after the other issues.
One last thing to test: Repeated basically everything above, but with the 85* locking piece.
Yikes. The only thing that could cycle more than one round at a time was the 124 NATO, and even that choked after only a few rounds.
Hilariously, I tried the Hush again. Turned the RPC into a friggon bolt-action. I'm pretty sure on some shots the bolt didn't even unlock!
Needless to say I'm pretty disappointed here. The only way it ran without failure was with 124 NATO and the 110* locking piece. When it did run, the recoil impulse was awesome. It's so light and it just snaps back on target. The charging/spring doesn't feel that stiff to me when cycling without anything in it. I'm suspecting my initial suspicion of the barrel not having fluting could be the main issue. The NATO ammo just flies out of there, but everything else just dribbles out if it ejects at all.
Not sure what I want to do here -- I believe another user here said they cut their recoil spring until it cycled properly. I might try to hone/polish the chamber first, though. It seems like if it just gets past the extraction it cycles perfectly and I don't want to mess with the recoil impulise or feeding by messing with the spring, especially since there's no spares we can purchase at the moment. If that doesn't work it'll likely be a call to Taurus at that point.
Taurus RPC 85 degree piece on top.
HK MP5 90 degree piece on bottom.
Unfortunately it appears they are not interchangeable.
A couple notes from when I disassembled the upper for cleaning/lubing that I don't think I've seen anyone mention: The recoil spring assembly has a plastic buffer that is spring loaded at the back. Also, the charging handle was stiff AF. I worked the action like 50 times with the bolt removed and then gave it a healthy dose of Lucas Extreme oil and it now feels a lot smoother/easier to charge.