I didn't have to dremel, but it is pretty tight.  I can tap it off with a small nylon mallet, just a bunch of small hits gets it to slide partway off, and from there I can pull it off.

No, mine installs/removes without issues. Fitting an SEF lower on the other hand has been the most difficult, due to the non-standard shelf that PTR uses. I'll be having that redone, and the barrel repressed, and the sling swivel mount all installed here soon, along with
a refinish job. My PTR K3P should be close to being finished now, so once I get that back, I'll start on my PTR-9C.

The bolt gap using a NEW HK Action 3 assembly with standard rollers is 0.26, which way out of spec. Putting in -6 rollers brought it down to 0.21, but I'd rather start with the standard size, hence having the barrel pressed in where it should be to start.

So does SBTactical just have that much variety in their braces or does PTR just have that much?

I fold the brace and use the mallet on the rear of the rubber brace which is folded adjacent to the receiver and tap where the buttpad of a stock would be so the direction is at the rear of the brace pushing to the rear of the gun.

I will probably get the dremel and sand out the wear spots on the brace this week.  My push pin is really tight too.

I got mine out today and put several hundred rounds downrange.  It was a mixture of a lot of brands and weights.  PMC Bronze 115, Blazer Brass 124, some Remington UMC I think 115, some WWB 115, maybe even another brand or two.

Gun is currently set-up with a German wide handguard, German Navy style SEF grip housing, SB Brace with the aluminum adapter sprayed matte Aluma Hyde II to match the painted guns finish.  Mags were OEM (KCI).

It ate everything with no issues.  It ejected clean.  Thread protector stayed put.  It kept a hole the size of a grapefruit at 25 yards and me shooting quickly without a whole lot of aiming.  Just quickly square up the sights and squeeze.  The mags ran perfectly and locked in fine.  

It has surpassed my wildest ideas of a PCC.  

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Unfortunately my 9CT is back at PTR for ejection issues as well.

I was wondering - if a brace is just a little tight, could the aluminum portion of the brace
that installs over the PTR 9CT receiver be heated up with a heat gun in order for it to slide
on easier.

I noticed the thin H style buffer in the SB brace was sort of eaten up by the bolt carrier.  I got a longer bolt with the same thread and head diameter and installed the thicker Choate/factory buffer from the OEM endcap into the brace endcap.

Dimensionally this will put the range of travel on the bolt carrier back to factory length.

Anybody had their SB buffer come apart?  Seems like I caught mine just before the carrier was smashing into the  SB aluminum endcap.

Came to post this, I have a Z5=RS that I SBR'd.  I bought 3 POF mags on the cheap to have some spares.  None of them functioned reliably.  The MKE mags work great in my gun and in my buddy's Omega and HK-94.

My PTR 9CT also battered the thin buffer that came with the SB brace, and ended up breaking one of the legs of the "H" somewhere between 600 and 875 rounds fired (a mix of brands mostly unsuppressed, and approximately 200 rounds suppressed, ranging from 115 grain to 150 grain.) I did some quick measuring with calipers and I concur with @cbsaf, the thicker Choate factory buffer that is 13.7 mm thick is the dimensionally correct buffer to use, rather than the thinner (4.92 mm) buffer that SB Tactical provides. I contacted SB Tactical about the buffer breaking and they were very quick to send me a new (4.92 mm thick) buffer as a replacement and replied that I could buy more buffers from HKParts when I asked about buying additional spares. SB Tactical has been fantastic to deal with and I have zero complaints about their product-- buy in confidence, just be aware that the buffer appears to be a wear item and, at least on my stock, I had to sand the interior of the brace to fit the PTR receiver.

As for my PTR 9CT, it took about 700 rounds to really break in. I did NOT use Winchester 124 grain NATO ammo to start, and that might have been my mistake and why it took so long to break in. I thought using the suppressor would increase the back pressure enough to make up the difference, but I was still having issues after 300 rounds and failure to eject problems appeared to be getting worse. Before sending it back to PTR, I decided to scrub the barrel chamber and face of the barrel and bolt really well and shot 200 rounds of the Winchester 124 grain NATO ammo through it and all of a sudden it is working perfectly and cycling anything I feed it.

I am extremely pleased with the PTR 9CT, the SB Tactical brace and the POF 15-round and 30 round magazines I bought. After the long break in process, they are working perfectly and it is quickly becoming one of my favorite firearms to shoot. Unfortunately, my wife thinks the same thing and I am in danger of losing it to her, as she has been known to abscond with firearms that "just fit her." I do wish PTR had included the MP5 cleaning brushes with the firearm-- I find them much more useful than the sling they provided and the brushes make cleaning the 9CT much easier. I currently have a red dot mounted on the rail, but I am not thrilled with the chin weld that is required to see through the dot. But, I have time to look into stocks with cheek risers while I wait for my stamp to turn this pistol into an SBR...

Here is my new buffer set-up.  It is the Choate buffer, a longer screw, and the washer is a #6 flat washer the same diameter as the Choate nylon locking nut.  I added blue threadlocker.  I also added another coat of Aluma Hyde II.

I suspect this will be a better set-up.

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When set up with the correct recoil rod & spring assembly the carrier should never touch the "H" buffer in an A3 stock. I wonder what or who's spring PTR is suppling in these guns.

Now that is some interesting info, @Clicker58. Would you mind sharing the reference material where that info came from and any other sources you might recommend so I can learn more about the roller lock design? I am new to the roller lock system as a user and so far I am finding it very intriguing (and fun.) Thanks in advance...

HK never saw the need to add a buffer to their fixed A2 stocks so why do it on the A3's? There are buffered A2 stocks available from at least one aftermarket source and I've modded one of mine in the same fashion.

I had a discussion regarding this mod with a certified HK armorer who pointed out that the BCG should never contact the stock back plate when set up correctly. When pressed on why they added a buffer to the A3's his feeling was HK was trying to reduce the recoil impulse and improve the comfort of the A3 stock rail against the shooters cheek.

With my MP5 the BCG doesn't hit the 1/2" thick buffer fitted in it's A2 stock, the MP5/10 is a different story.

Ref. PTR 9CT: If the h-buffer in the SBT5 MP5 Folding Pistol Brace fails, could the H-buffer in the
PTR supplied end cap be used in the SBT5 MP5 Folding Pistol Brace ?

The PTR end cap is a choate brand. The OEM PTR/Choate buffer is exactly what I used above.  All you need is a longer screw.

Thanks, I'm going to do this mod this weekend.

Also, if anyone has figured out a good solution for adding an HK sling eyelet to the front post assembly please share with the group here, as well.

The lack of eyelet does not bother me however if I had to have it I would buy a surplus H&K eyelet and take it to a machine shop have them chop the eyelet off and weld it to the end of the larger PTR pin.  Spray with some epoxy paint, reinstall the pin and call it a day.  Whole thing could be done for a few bucks.

cbsaf: What thread rate is that there screw ?

Weird, my Toad Bailey specials run like tops.

Great question, I don't know for sure.  It is a screw that holds a light switch or electrical outlet into the wall box.    They are all a standard thread pitch and are also the same thread pitch as the SB brace buffer hole.  I assume you can get one separately at Lowes/Home Depot/Ace.

The google tells me it is a 6-32 x 1?.  I shortened it to just over 3/4" long.

You might want to recheck that thread pitch-- mine was 8-32. You will have to cut a 1" long screw to fit properly, or you can use a 3/4" screw and not thread it all the way through the brace. The new buffer that SB Tactical sent me in replacement is already showing similar wear after 500 rounds. I will keep an eye on it and keep running it until it breaks. I haven't found any sources that compare buffer life, so I bought several different buffers and will test them for long term durability. Might be a while before the results are available, but it might be interesting. If nothing else I will know which buffer I will stock up on in the future. I am hoping the thicker buffer will last much longer then the OEM buffer, but it will see more impact much sooner in the cycle than the thinner buffer, so it might wear just as fast or even faster. Only one way to find out...

It may be 8-32.  I just found one in the tool chest and it spun in freely.  It was the screw that holds a light switch into an outlet box.

I took an HK eyelet and took a chisel and basically chiseled dents in to the shaft of the eyelet to displace some metal. After words I had to drive it in with a rubber mallet. If it does not hold I might just weld it on the right side.

So I took it out again last weekend.  Same results.  Occasional jams as before.  However, just as an experiment, I mounted my Gemtech GM45 suppressor on it and tried again.  Surprizinly, it feed everything from every magazine I tried, even the ETS.  No problems.  So what did the suppressor do that made it work? How do I duplicate the results without the GM45 mounted?  I am perplexed.

if an increase back pressure helped then maybe recoil spring is out of spec or trigger spring is too strong?  long shot  is maybe wrong locking piece.  I know it sucks when you have only one example of a firearm, you have nothing to compare to or working parts to swap out.

Put about 500 more rounds through since putting the PTR/Choate buffer into the SB Tactical brace cap.  Everything is working great.  No significant wear on the buffer, no issues with the longer screw, no ejection or bolt travel issues.  I'm a happy camper.

My clones were always finicky with ammo. Wound up changing out the bolt to an RCM and the problems went away.

UPDATE:  Took it back to the shop I purchased it at and they sent it back to PTR to figure out.  Got it back yesterday.  Put around 300 rounds through it this morning from eight different mags with seven types of ammo.  Had one failure to fire on the 27th round of the first mag. No problems at all after that.   Shot suppressed and unsuppressed, fast and slow.  No failures of any kind.  Even used Wolf ammo and ETS mags, perfect function.  PTR replaced the extractor, ejector, and deflector.  All ejected rounds landing in nice, consistent patterns, depending on the ammo type. Accuracy was great, as expected.  I am happy.

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Did they say what they did to the gun?

Just put one of these on it.

http://madkc.com/

My SBR'd Toad Bailey gun runs like a top after some tuning.  You guys are spoiled.  And knock it off with the cheap mags and ammo.  Geez 115gr WWB and Wolf?  Is it 2004 around here?

Someone mentioned Miwall 125gr, that is about 80% of my diet in 9mm.

Oh and straight H&K mags are finicky, there is a reason they were replaced with curved ones.  My straight mags hate hollowpoints and subsonic weight bullets.

PTR replaced the extractor, ejector, and deflector.  All mags run fine (so far) with all ammo, including the straight mags.  I shoot what ammo I can get a good price at the time.  That includes Wolf and WWB.  My other SBR's (Uzi, Scorpion, AR9) all function fine without any problems using Wolf, Tula, and WWB.