USP9c / RCM / Octane 9 feed issues

Need a bit of advice on the following. Picked up a NIB USP9c v1, dropped in a Rim Country Manufacturing threaded barrel and had some initial feeding problems with AE9FP. Chalked it up to any number of things. New gun / RSA, new gun / hammer spring, dirty mags, dirty / unlubed piston, weak ammo. So I swap the barrel into my v7 that has 7446 rounds through it, and immediately have the same issues. Below is a representation of the issues. Note that this is after cleaning and lubing the piston, cleaning the mag, and a gun with 7400rds through it. Temperature is 25 degrees but gear just came from inside, and did not reach ambient temperature, so no frozen lube or piston o-ring.

On occasion, a fired case will be ejected, along with a live round, and the gun will chamber.

7th rd
Attachment 23014
10th rd. The top round is just sitting there, the 11th round is trapped by the slide and mag body
Attachment 23015
13th and final rd. This one is actually just sitting in there and the gun is at slide lock
Attachment 23016

These type of issues have presented themselves over 1 brand new gun, and one with 7446 rounds through it. A thought I just had, is using new mags in the used gun. I don't recall if the new mags from the v1 were used with the new gun. I doubt it as they have the finger rest, and it does nothing for me. Amy other thoughts or input would be greatly appreciated.

I had almost the exact same issue in my P2000 9mm with an RCM threaded barrel, using a Griffin Armament Resistance 9. I tried all kinds of ammo, etc...nothing worked. Misfeeds, a few good shots, then a live round would eject along with a spent casing, then another misfeed...repeat randomly.

I then tried it with a lighter suppressor (an AAC Illusion) and it started to function %100. No more misfeeds, no live rounds blurting out the port. I tried for around 50 rounds to get the Resistance to work right; once I switched to the Illusion, I went > 100 rounds trouble-free that session.

I'm guessing the can was just too heavy for the system. That's all I could come up with, all other things being equal.

Quote:

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Originally Posted by obremski

I had almost the exact same issue in my P2000 9mm with an RCM threaded barrel, using a Griffin Armament Resistance 9. I tried all kinds of ammo, etc...nothing worked. Misfeeds, a few good shots, then a live round would eject along with a spent casing, then another misfeed...repeat randomly.

I then tried it with a lighter suppressor (an AAC Illusion) and it started to function %100. No more misfeeds, no live rounds blurting out the port. I tried for around 50 rounds to get the Resistance to work right; once I switched to the Illusion, I went > 100 rounds trouble-free that session.

I'm guessing the can was just too heavy for the system. That's all I could come up with, all other things being equal.

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Great points.

Somehow I missed your reply, and came back to update.

Made some additional observations, but still not 100%.

I typically shoot soda cans suppressed at 50 yards for the challenge. Thought I might not be gripping as hard as I normally would, in order mitigate wobble. Also thought the gloves may have been dragging on the slide. Tested my theory several times, and it seemed to prove true. Then the malfunctions came back. Crush grip, weak grip, no glove drag, etc. and still had occasional issues. It would be great to have a slow mo video of what is or isn't happening. Also observed brass transfer on the front of the ejection port.

Trying to see if this justifies a lighter can.

It seems to me in my very, very, very limited experience that HK guns that weren't designed to accept a can (strictly going on the lack of HK factory threaded barrels as my criteria) don't seem to like running right when they're forced to accept one. I have a USP 45 that I've sort of manually converted to a USP Tac (replaced the recoil spring assembly with the correct one, factory threaded barrel, taller sights) that runs with a Griffin Revo 45 like it was made for it. Shooting it without the USP Tac-specific recoil spring assembly, it worked...but wasn't nearly as pleasant; it would unlock early and basically sandblast the user. With the correct RSA, it seems to hold on before unlocking that much longer, making it a far more comfortable, and even quieter, experience.

The only USP compact that HK has a factory threaded barrel for, according to the interweb, is the USP Compact 45.

Honestly, I came to the conclusion that as much as I'd love to shoot my P2000 with a can on for it's life with me, it's just not a great can host. Not nearly in the same league as the USP 45/USP Tac. If you really want to use the can, I'd suggest either a different host (Sig classic P-series? I have a threaded P99 that's surprisingly good as a can host as well) or something lighter and all aluminum for a can (my Illusion is stupidly light, and all aluminum...the Griffin Resistance is similar to the Octane in that it's got an aluminum tube but steel baffles). Obviously this has downsides with regards to can/baffle longevity as well as ease of cleaning, if that sort of thing is high on your priority list.

Alright, I am happy to provide the following update. After handling an abused Obsidian 9 by Rugged, the other day I came to the theory that my o-ring may be the culprit. The Obsidian I handled was the range rental, fairly dirty and bone dry. However the piston and booster were easily removed by hand, and the o-ring provided very little resistance. Unlike my Octane, the moving pieces required very little effort. I checked my manual and confirmed that it can run without the o-ring, and promptly removed it. At the expense of some additional noise, it functioned perfectly. Seems as though I may have some slightly oversized o-rings. Never really compared how much force was needed to work the piston. May need to look into other options as replacement rings.

Interesting, I had not considered that. On the GA can I was trying out with, I had recently replaced the o-ring in the end cap that the booster seats in, and the o-ring in the cap of the Illusion that worked just fine is a bit loose...I really hadn't considered that angle. Huh, I'll have to see how it works when the o-ring is broken in on the GA can then...

To circle back to this - went back the other day with my P2000 and RCM barrel, with the GA can, and %100 function. I've used the can a bit with some other hosts before taking it back out again this time with the P2k so I can only guess the o-ring in the cap "broke in", and allowed it to function a lot more smoothly this time around. No misfeeds, no other issues. I also lubed the crap out of the piston this time around, so that might have helped.

FWIW, with Trijicon HDs, the top of the front sight is just even with the top of the can...not quite suppressor height sights, but very usable.