Yeah, I know, these things are easy as pie to install. Here was my experience and am sharing it only for informational purposes. Had a clearance issue with the bolt catch I used for this lower (apparently Seekins bolt catches and Spike's billet uppers do not play well together.) Needed to remove the brace so I could get a punch on the bolt catch pin during the trouble shooting portion of this sordid tale. While taking it off with my armorers wrench (the good kind, not the chinese amazon special) I was kind of surprised when the actual metal on the teeth of the castle nut portion of the buffer tube let loose and got all kinds of chewed up. I wasn't dainty when putting it on, knowing there was no way to stake it, but I didn't get all caveman on it either. It is definitely softer then your normal castle nut so be careful. I was applying inward pressure with my off hand on the wrench to make sure it stayed in contact, metal to metal, while I was trying to remove this thing to prevent wrench slippage as well. Thankfully I have a flat black bluing pen which should cover up the ugly. But that thing is on to stay at this point. My point is, make SURE you have function checked EVERYTHING with the upper installed before you tighten down the "castle nut" on these things for good. Go hand tight to begin with, do all final assembly and insure clearances, and then go back and snug it up with the wrench. Much cursing later, I knocked the bolt catch pin out from the back side (chased the plunger and spring across the garage floor for good measure,) replaced it, and then used the vice grip method to reinstall.

Good info, Dutch.

Guess I simply got lucky installing mine. I didn't have any of these issues.

Try reading the op again. Did you have any of these issues uninstalling it?

Seems half of my post did not make it.

"I did not have any of these issues when I removed it from a dedicated 9mm lower and reinstalled on a .300 Blackout lower."

I do have a castle nut wrench that engages in three positions. Not sure if that is what may have helped, bit it is a much better too than the castle nut wrench I have that only has one contact lug

that makes more sense. 

I used a Magpul wrench which has multiple contact points as well. I believe three?

I've not used that one. Have you contacted them? I wonder if you received a soft tube?

mine worked fine , maybe your wrench slipped

Couple of responses

1.) I do have a second brace on my 5.56 pistol and had no issues putting it on or taking it off. Given my experience with the first one, I took extra caution when snugging this one down.
2.) I have tried to contact SB Tactical via their support page and Facebook only to inquire about buying a replacement. No response yet.
3.) Wrench didn't slip. See my OP about keeping pressure on it to make sure it didn't do that.
4.) The wrench I used had multiple engagement points. I've used this same wrench on many AR builds with no issues.

Not sure if this one was just softer than normal or I applied too much force then the metal could handle. You can tell from the gouges that were made that it dug into the supporting metal around the "teeth."

My only intent was to let others know to not apply too much force on these when you install them. Not slamming SBT or the brace. I really like this thing and will continue to be a big fan of them.

I don't think anyone got the idea you were bashing the product.
My intent was not to try to contradict your statements, simply to learn what happened.

With good products, tools and techniques, this shouldn't have happened. The ball was dropped somewhere.
I think the part is to blame here.

Oh, no worries at all! I didn't take offense to anything folks posted and sure hope I didn't come off that way. I am sure I am partially to blame, given I did give it that extra little nudge when tightening it.

After connecting with SBT via Facebook, they don't offer replacement parts. I think they can barely keep up with production demand at the moment. Emails to their support address had gone unanswered so I messaged them on the book of faces. They directed me back to the support email address to check to see if status has changed. But it continues to go unanswered. No phone number listed for them either. I noticed that Maxim, on the other hand, lists replacement parts and has several means of contacting them, including phone. Odd since SBT makes both lines. Love the SBT product but not impressed with customer support.

Well that sucks

I'm pretty sure SBT makes the brace part, and likely the longer buffer tube, etc that is specific to their model. Maxim's version is literally a Maxim PDW stock with a molded rubber brace in place of their normal buttstock part - SBT isn't making any of that other than the rubber piece. They worked together on the development, and up until a month or so before release, SBT's product photos were identical to Maxim's. I suspect it was a question of sharing the market that caused SBT to alter the design enough that they weren't charging $100 less for the exact same product. 

I stand corrected. I remember the SBT pics being identical to the Maxim version and just ASSumed that they were making it for them.