I finished building a pistol lower with the exception of tightening down the castle nut as I don't have a bench or bench vise.

Buffer Tube: KAK Shockwave
Brace: Shockwave (it's already attached to the buffertube
End Plate: Timber Creek Outdoors QD (aluminum)

Yesterday I took it to a friend who has a bench and to my dismay noticed that after I tightened down the castle nut that the orientation of the "blade" on the brace was about 15 degrees off vertical. HOLY CRAP! THE BUFFER TUBE CONTINUED TO TURN EVEN THOUGH IT WAS LOCKED IN BY THE END PLATE

So we loosed it up and ended up moving the orientation of the blade (thus the buffer tube) about 7 degrees off vertical the other way.

In other words we had to "time" it.

What the hell's going on? My friend said he had the exact same problem when he built his lower using same buffer tube only his end plate was a steel mil-spec tube.

I am torn between disassembling the buffer tube (and I have a pretty good idea I'll find damaged buffer tube threads and a sheared off positioning tab on the inside of the end plate) or just leaving it alone as it's completed and everything's tight.

Can someone please chime in?

(ETA: my first pistol build used a KAK Shockwave buffer tube and a Magpul ASAP QD end plate and we had no issues with it.

Received this response from Kurt at KAK Industries:

I'm sure the tab has yielded on your endplate and damaged the threads.  your tube is still plenty useable but will need to be aligned by eye.   it's also a good idea to capture the buffer tube when tightening.  the slot is really not ment to hold all the torque even on a mil spec tube


Exactly what I suspected. Damn.

So how's the best way to capture a tube such as this? Geisselle does not make a Reaction Block to fit the KAK Shockwave tube and if it did it's too rich for my blood.

The anal retentive in me will not allow this to stand. I'll have to buy a new tube and a new end plate.

Need to pick up a strap wrench, the Harbor Freight brand is just fine for holding tubes and tightening the nut.

HF Strap Wrench

It is a good idea to keep as set around for all them little quirky things that need to be held while tightening.

https://www.ar15.com/forums/ar-15/KAK-Blade-Tube-Issues/66-724286/

My issue.

Good thing there's a Hazard Fraught Tools less than a mile away but I'm confused as to how you'd use it. Details?

The rubber strap will tighten around what you want to hold and it allows you to tighten the set nut, what is nice, is they will fit irregular shapes, so you would be able to leave the shockwave on the tube and still tighten it down.  When you put the rubber strap around something in the correct direction, it will tighten on itself to give a firm grip on it and won't allow it to turn.

Hope that makes sense.

Strap Wrench Instructions

I've installed quite a few with mil spec end plates that needed "timed".  A little too wide of a slot in the tube (or narrow tab on the plate) makes a big difference.

Often times you will need to hold the tube into position and tighten the nut a little at a time backing up the tube as you go. If you just rely on the back plate/tube connection for alignment it will not necessarily end up straight.
Try to keep the tube turned a bit to the right so your final tightening of the nut spins it straight.

A new KAK Shockwave tube and Timber Creek QD End Plate have been ordered from Skid Tactical and JoeBobOutfitters respectively.

Happened to me quite a bit. Best thing to do is install the blade or a stock and apply pressure in the opposite direction it wants to turn as you tighten the castle nut.

It's mainly an issue with 6000 series alluminum buffer tubes (which I believe the shockwave tube is).

Actually no, it doesn't.

How do you tighten the castle nut with two hands while you're holding the handle to the strap wrench with the other hand?

Sounds like a two-person 4-hands job to me. You'd put the Shockwave brace on the tube of the assembled lower then place the top of the brace in a vise. While one person holds the strap wrench the other person tightens the castle nut.

I use strap wrenches all the time.  But if you can't figure it out, then I don't know what to tell you.

do you have a picture of the aluminum endplate?

No, but the "tab" inside is broken off.

Tapco castle nut wrench only requires one hand. Use a magazine block to hold the lower in a vise.

Parts arrived yesterday so we'll give it another shot maybe this weekend. In addition to using my BEV Block (more for stabilization than immobilization) I'll also be using a HFT strap wrench to capture the buffer tube and like before a 2nd set of hands.

I'll pass on using a Tapco CAR castle nut wrench. They are too short to apply necessary torque and paired with a torque wrench too awkward.

It's actually much easier than you would imagine. You just need to orient the strap wrench in a way that holds it in place, such as braced against the table or against your body.

Have you ever loosened a nut and bolt by letting the wrench rest against a frame or something, to keep it from turning, while using a socket on the other end? Same idea.

Gotcha. The handle can rest against the front of the workbench. Will also mark the top of the buffer tube with a pencil so both of us can see if the tube starts to rotate again.

Scored those strap wrenches at HFT this morning. They're on sale for $3.99 and they also accepted a 20% off coupon.

Actually the tab on the endplate was NOT broken off (I was finally able to get it disassembled last night as previously I had no wrench). The threads on either side of the buffer tube groove were fooked.

So we'll get this thing put together using the same end plate and a new buffer tube.

I think this current pistol build will be the last using a KAK Shockwave tube and Shockwave brace as SBT and Gearhead Works offer braces that use standard mil-spec buffer tube or a reasonable facsimile. Easier to capture and not half the PITA to install and work with Magpul's wrench.

I’ve done this a few times, highly annoying. Frankly I think I’ve just been ober-torquing them.

As the fellow ARFCOM member who has a bench vise (I have none) lives on the other side of the city I decided to plunge forth on my own and use the "two knees on the carpet" method: left knee on the grip, right knee on the blade portion of the brace, and the Real Avid wrench  at approximately 45 degrees off horizontal. Push the wrench handle down and....DONE.  The brace might be 1 degree off but it's barely noticeable. Certainly not anything to cause any loss of sleep. No marring of castle nut, tube, or Timber Creek QD end plate.