Wondering which is a better fit for the SBA3 brace?  The standard 7-position A5 buffer tube or the 6-position (known as the RE-10/A5SR) buffer tube?  Going on a 10.5".  Thanks.

Make sure your brace does not extend past 13.5'' LOP or the ATF could have an issue with it. I'm not sure if either tube will allow the brace to extend past the recommended max length.

Both tubes measure under 13.5" LOP with SBA3 fully extended and, as I understand it, no one has been able to confirm if greater than 13.5" is legal or illegal, correct me if I'm wrong.

It's just an opinion from an ATF agent.

I like my stocks at 12.5" LOP and I could use an arm brace with 14.5" LOP, so the number 13.5 is to me.

Gents,

I installed a BCM A5 receiver extension (buffer tube) on my latest pistol build.  The A5 extension is 3/4 inch longer than the standard carbine receiver extension. Is the Vltor extension longer than the standard carbine extension  ?

If you use a standard carbine buffer in that set-up the bolt will travel too far to the rear and your gonna have problems. You will need a 3/4 inch spacer in the end of the receiver extension.   I picked up a receiver extension spacer for a 9mm AR carbine - 3/4 inch in length.  Works like a charm !

By going to the A5 extension I was able to pick up 3/4 inch in the length of pull with the SBA3 brace.  I'm now right at 13 1/4 length of pull.

Hope this helps

I have all 3 of those components and can test this out for you when I get home this evening and let you know if there is anything worth noting.

Thank you, I know with the standard 7-position A5 tube, you cannot fully collapse the SBA3 brace, wondering if the 6-position is better?  I also put a request in to Vltor so I'll post back and let you know what they say.

A5 receiver extensions are designed to work with A5 length buffers that are longer than carbine but shorter than rifle buffers. There's a wide variety of weight options.  The A5 design is an entire system.

Side note, on a 9mm build you can use one of the heavier A5 buffers with a carbine extension to avoid the need for a spacer since it's an extra 3/4" long.

Some quick tests:

7 POS A5 = 5 total clicks of adjustment, at longest extension the #2 can be seen on top of RE in front of the leading edge of the brace. Roughly 13 1/8" lop on a tape measure with MBT trigger

6 POS A5 = 5 total clicks of adjustment, at longest extension the #1 can be seen on the top of the RE in front of the leading edge of the brace. Roughly 13" lop on a tape measure with a USGI trigger.

Neither combo had what I call excessive over travel, whereby the brace can collapse so much it's fully in between a notched position. Both braces could slightly over travel a hair but nothing that would cause a false lock. I really couldn't see much of a difference between the two RE in this combo other than the numbers exposed on top of the RE, which don't mean all that much with the SBA3. The slight lop difference may just be the different triggers used, or just my tape measure techniques

Side note. With a Magpul fixed carbine stock and the A5, not for pistol configs, the Re-10 has a shorter 'nose' for the adjustment channel under the RE and the fixed carbine stock can, in some cases, be pulled to the rear a little if the cross bolt tension screw isn't really tight on the stock.

Side note #2. Large frame lowers for AR10/LR308 etc can be longer dimensions behind the trigger, depending on specific make, that contribute to longer lop for anything attached to any RE.

Would the SB03 and the 7 point buffer tube along with a 8.3" barrel make the OAL of the setup 26" or longer? Does anyone know or can measure?

I think since the A5 RE is only .75" longer than a standard carbine extension, you should be under 26" OAL with an 8.3" barrel.

Here is the reply I received from Vltor about the different tubes:

"Due to the design of the SBA3, either tube will work. The 7-position tube’s extra position (over that of the 6-position tube) is actually farther forward, not farther back. The SBA3 has it’s indexing pin and adjustment lever backwards when compared to a standard adjustable rifle stock, so it’s only able to go back so far (to limit overall LOP). Either tube will function. You may have a hard time finding the RE-A5 tubes at the moment, so that alone may be a good reason to go with the RE-10/A5SR."

That answers my question, along with the gentleman's help above.