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Discussion Starter #1
I have a problem with my PTR 9CT -PTR 601. It came with a SB Brace along with the end cap. I installed the SB brace and just like others posted, it was a chore getting the push pin to line up. However that is not my main problem. The problem I’m reporting is when I took it to the range I was able to fire one round before the bolt group went way back to the rear of the gun and stayed there. It came forward when I removed the back push pin. I tried it again same result. I tried firing it with the end cap instead of the brace and it appeared to work fine.

I took it to a gun shop where they replaced the spacer on the inside of the SB brace with a different size. I took it to the range to test it and found that with 115 gr ammo it work fine. I went to 124gr and the problem occurred again but this time not as extreme. I was able to get the bolt freed and come forward by just hitting the side of the gun with the palm of by hand. However I went back to 115 Gr and then back to 124 gr this time both types of ammo fired without incident. I also fired 147 GR without the problem occurring .

I cleaned and oiled the gun and took it to the range again and the same thing happened, 115 gr worked fine, 124 gr bolt frozen to the rear, back to 115 gr then 124 gr again and it appeared to work fine.

I was only using commercial loaded ammunition namely Federal and American Eagle, the gun was well lubricated and these events occurred with multiple magazines.

It appears that the gun doesn't like the SB brace.
My question is; does anyone else have this issue if so what is the remedy?
 

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I own a PTR 9CT and SB Tactical SBT5A pistol stabilizing brace.. Even with your description, I'm unable to figure out how you managed to get that malfunction. It sounds like you forgot to attach the buffer spring and guide rod behind the bolt carrier assembly. NOT in front! The spring/rod combo keeps the bolt carrier assembly firmly pushed forward, and it takes some effort to lock the cocking handle to the rear.

If you are reassembling it correctly:
  1. The bolt head (silver) goes into the receiver first, guided by the black bolt carrier which rides the grooves of the receiver. The buffer spring/guide rod are seated behind the bolt carrier and will stick out a little bit from the back of the receiver
  2. Attach the lower housing next, because the bolt carrier assembly won't slide down if the housing came first.
  3. The end cap of the SBT5A brace will attach to the rear of the receiver/pistol grip. The buffer spring will touch the dimple inside the end cap.
If you pull back on the cocking handle, you should feel a firm resistance and the buffer spring would return the bolt carrier assembly back into place when you let go.
 

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Discussion Starter #3
I own a PTR 9CT and SB Tactical SBT5A pistol stabilizing brace.. Even with your description, I'm unable to figure out how you managed to get that malfunction. It sounds like you forgot to attach the buffer spring and guide rod behind the bolt carrier assembly. NOT in front! The spring/rod combo keeps the bolt carrier assembly firmly pushed forward, and it takes some effort to lock the cocking handle to the rear.

If you are reassembling it correctly:
  1. The bolt head (silver) goes into the receiver first, guided by the black bolt carrier which rides the grooves of the receiver. The buffer spring/guide rod are seated behind the bolt carrier and will stick out a little bit from the back of the receiver
  2. Attach the lower housing next, because the bolt carrier assembly won't slide down if the housing came first.
  3. The end cap of the SBT5A brace will attach to the rear of the receiver/pistol grip. The buffer spring will touch the dimple inside the end cap.
If you pull back on the cocking handle, you should feel a firm resistance and the buffer spring would return the bolt carrier assembly back into place when you let go.
LOL. I know that wasn't the problem. Even if I didn't detect that, the gun shop that I took it to have it repaired would have. I took it back again today. They told me they suspect that the SB brace is too tight where it is pinching the back of the receiver and causing the bolt to stick. In any event they said they will have another look at it and possible call PTR for assistance.
 

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Im having the exact same problem as you when I install my brace. The gun fires just fine when the push pin is completely removed, but when it is installed the bolt locks on every shot. Did you alleviate your issue?
 

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My LGS had a customer who also has a 9CT with the same problem. The problem is the SB brace. I believe the customer got in contact with SB Tactical. They sent him a new SB brace and it worked fine after.
 

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Discussion Starter #6 (Edited)
Im having the exact same problem as you when I install my brace. The gun fires just fine when the push pin is completely removed, but when it is installed the bolt locks on every shot. Did you alleviate your issue?

My LGS had a customer who also has a 9CT with the same problem. The problem is the SB brace. I believe the customer got in contact with SB Tactical. They sent him a new SB brace and it worked fine after.
I didn't try it without the push pin installed. However as mentioned in my post I had a great deal of difficulty installing the SB Brace push pin. I got my SB brace for free as part of an buyer incentive from Atlantic firearms in Feb 2019. The gun shop still has it and the last I heard was that they were in contact with PTR who suggested to ream out push pin hole on the SB brace. I hope the gun will be ready by next week. Turns out that free SB brace wasn't so free after all.

Thanks for replying.For a while I thought I was the only one with the problem. ( Not to say I would want anyone else to experience this.) I will update the post and once I get the gun back or if another remedy is being made.
 

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I am having a very similar issue with my 603 using the SBT5KA brace. I only had 2 mags worth of 115 gr to test but it all ran smoothly. My problem was with 147 gr, both with and without a suppressor. I also had problems with 124 gr. The buffer block that came with the brace has been destroyed , the carrier assembly is striking the bottom right part of the brace just below the buffer block. I also had a binary trigger installed. Before I found the damage I thought I would need to replace the locking piece, I've read that MP5Ks running a can and 147s need the 80 degree. Unfortunately the US made one from HKparts doesn't fit, and I'm not willing to drop $200 on the German made one if there is a chance it wont fit.

I returned the weapon to the factory configuration and will try shooting it tomorrow to see how it does.
 

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For comparison, I got mine in November and and haven’t had the issue OP described. Only issue with the brace other than being hand to get off the receiver is the little blue rubber piece inside the end cap has started to come apart, but that’s it.
 

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Finally got back out to the range to shoot mine. Put factory trigger and endcap back on. Got about 6 rounds out a brand new HK mag before it jammed. It went downhill fast after that, Was getting a variety of jams every 1-2 rounds. double feed, failure to extract, failure to feed, stovepipe, and somehow empty brass getting jammed above the bolt. Guess I will be contacting PTR and sending it to them. I will say that the PTR endcap and buffer held up much better than the brace.
 

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Before I found the damage I thought I would need to replace the locking piece, I've read that MP5Ks running a can and 147s need the 80 degree. Unfortunately the US made one from HKparts doesn't fit, and I'm not willing to drop $200 on the German made one if there is a chance it wont fit.
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I dont see that PTR sells an 80 deg . LP on their website for parts.I beleve they make their own bolts & LP’s in house? Apparently those bolts are out of spec to the point that other known LP ‘s wont fit.You could ask ptr about an 80 LP but they might tell you running it suppressed will void the warranty?If that is the case you might want to get an RCM bolt with their 80 LP .

The achilles heel of the 9x series is the extractor spring.Once it is toast,...all subsequent attempts to fire gun will be as you described.To counter this some like myself carry a spare bolthead with good spring all ready to snap in so you wont waste time fiddling at range .That or the mad max bolthead .
 

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Finally got back out to the range to shoot mine. Put factory trigger and endcap back on. Got about 6 rounds out a brand new HK mag before it jammed. It went downhill fast after that, Was getting a variety of jams every 1-2 rounds. double feed, failure to extract, failure to feed, stovepipe, and somehow empty brass getting jammed above the bolt. Guess I will be contacting PTR and sending it to them. I will say that the PTR endcap and buffer held up much better than the brace.
I have the binary trigger also. It’s amazing how quick the Sb buffers gets destroyed. I also bought the hk parts LP and an RCM LP and neither fit. I’m gonna send it back to PTR.
 

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I also bought the hk parts LP and an RCM LP and neither fit. I’m gonna send it back to PTR.
If the return is based solely on the fact that other manufacturers locking pieces won’t fit their proprietary bolt head....they may tell you to go pound sand....just sayin....
 

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I have the binary trigger also. It’s amazing how quick the Sb buffers gets destroyed.
I run a binary and an SB brace on my PCS-9 reverse stretch & after several hundred rounds the blue buffer still looks almost new.This leads me to believe there may be other issues at play in your setup.
 

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I am curious as to what ptr says about the 80 degree locking piece as well. I too have the hk parts and rcm and they don’t fit. I would really like to run 147s suppressed without having to replace the bolt head.
 

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I run a binary and an SB brace on my PCS-9 reverse stretch & after several hundred rounds the blue buffer still looks almost new.This leads me to believe there may be other issues at play in your setup.
Ptr sent me an RMA label and asked me to include the locking piece with the gun. I’m hearing mixed reviews from people saying their buffers are fine and some get beat up. Could be an SB brace fitment issue. I’ll keep updating my progress here.
 

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I am curious as to what ptr says about the 80 degree locking piece as well. I too have the hk parts and rcm and they don’t fit. I would really like to run 147s suppressed without having to replace the bolt head.

I’ll update this thread with progress. I want to form 1 and suppress this but so far I’ve been frustrated with the gun not functioning the way it should. Credit to PTR for outstanding CS so far. They’ve been accommodating. Hopefully it will all get worked out.
 

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Never had anything that bad happen but ive always hated the fit on my sb braces, the pins always have to be tapped in and out with a hammer when i install them.. kind of defeats the purpose of having push pins
 
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