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hlhneast

SB M4 Pistol Brace

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The brown truck dropped off my new PSA 11.5" upper assembly Saturday. Ever since I saw a pic of the 733 Commando I wanted to build one. Since I dont have a stamp, now I am faced with a decision to pin and weld some type of barrel extension or pistol brace it. While the SBM4 looks the most military it certainly isnt a CAR stock so the "clone" is now a 733(ish) build. I hate losing the short barrel with some kind of extension so the brace will be my choice.

 

Now, all I find with the xescription of the SB M4 is that it fits standard pistol buffer tubes. This will be my first AR pistol so I am a little confused as to what a "standard" pistol buffer tube is. Ive seen tubes with a bit of foam on the end and ones without the foam. They are generally a simple smooth tube and I have also seen fluted ones. Can someone please point me to a "standard" tube?

 

Thanks!

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Tube diameter for braces is a slightly smaller OD than a regular stock tube. Fluted or not doesn't matter. What you don't want is a tube with the adjuster rail like a normal stock tube.

The thing that seems to vary (not standard at all) between tubes that matters is the length. Without getting carried away in my search I bought the longest "pistol" tube I could find, and when I installed my SBM4 the tube was still an 1¼" shorter than the brace, so it isn't flush across the end.

So what I would suggest, is that you spend more time than I did and find the longest "pistol" tube that you can. The fit will be tight enough that you will need to use talc to dust the inside of the hole on the brace and the outside of the tube before pressing it on. Use the floor or a sturdy bench top to press it on or you will frustrate yourself.

 

I hope this helps.

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The fluted RRA tubes are too thick for most braces. Try looking a KAK Industries for pistol buffer tubes with shims to adjust length.

Edited by gmor

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This looks like the answer. 10.5"-14.5" LOP and designed with SB in mind according to the description. The SBM4 is an enhanced version of the SB15 so I hope it will work. I will call Wing Tactical tomorrow to make sure.

 

https://www.wingtactical.com/firearm-parts/ar-15/buffer-buffer-tubes/odin-works-sb-pt-adjustable-ar-pistol-buffer-tube/

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I have a 7" pistol tube and the talc thing didnt work for me. Probably operator error (gettin good at that) I put the lower in the freezer, the brace in HOT water for a few minutes. took them out. oiled inside of brace, outside of tube and it was almost like throwin a hotdog down a hallway. Worked slick

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This looks like the answer. 10.5"-14.5" LOP and designed with SB in mind according to the description. The SBM4 is an enhanced version of the SB15 so I hope it will work. I will call Wing Tactical tomorrow to make sure.

 

https://www.wingtactical.com/firearm-parts/ar-15/buffer-buffer-tubes/odin-works-sb-pt-adjustable-ar-pistol-buffer-tube/

Looks like the hot ticket! If I build another pistol lower I'll use one.

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Looks like the hot ticket! If I build another pistol lower I'll use one.

Yessir. I have the spring and buffer so I am good. WingT sells the little locking ring separately if that will help you out with your present one.

 

Now I have to search out the best price. So far WingT has the best price. Looking for the SBM4 as well. $105/Free ship on the "bay.

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My pistol build has the Sig Brace quite firmly stuck on the tube nowhere near fully seated against the receiver. I cannot remember where I got the pistol buffer tube.

 

I really wish I could talk myself into getting a stamp for an SBR. I really like how the 10.5" barrel feels on this "pistol".

 

arpistol.jpg

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My pistol build has the Sig Brace quite firmly stuck on the tube nowhere near fully seated against the receiver. I cannot remember where I got the pistol buffer tube.

 

I really wish I could talk myself into getting a stamp for an SBR. I really like how the 10.5" barrel feels on this "pistol".

 

arpistol.jpg

Yeah I can spend $200 buying the parts to make this a legal pistol or send the ATF $200 for an SBR stamp and have it sit around for months waiting on it..

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I have the SMB4 it is a tight fit and isnt going anywhere once you put it on.

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I have the SMB4 it is a tight fit and isnt going anywhere once you put it on.

Thanks!

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I have the SMB4 it is a tight fit and isnt going anywhere once you put it on.

FWIW there is a small vent hole at the rear of the SB M4 stock. If you place your weapon muzzle down, get the brace started on, then cover the hole with your finger and the stock pushes right on and fits tighter than a rat's ass. Covering the hole makes the air inside the brace needing a way out, and the only way out if the hole is plugged is to force its way out alongside the tube, expanding the brace temporarily. Once the brace is seated and the air has escaped, the rubber conforms tightly back onto the tube.

 

Forget talc, oil, heat, cold, dish soap, etc. This method works.

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I am disappointed in the Odin Works tube and SB M4 combo. The brace is very loose on the tube until it pushes all the way up to the receiver. SB's suggestion of using duct tape or electrical tape to take up slack didnt impress me either. I sure as hell dont want to spend $160 and wrap duct tape around something to make it work. I guess I will figure out something.

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Well that sucks. I wouldn't be happy with that either.

FWIW, I'm not altogether dissatisfied with my $12.99 universal pistol tube that I got from TSG. If it were 1"-1½" longer I'd be downright thrilled with it.

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