View Full Version : AR15 SBR questions

January 31, 2011, 06:37 PM
So i am in the process of re doing my ar. I have a RRA Entry Tac A3 with some acc's and mods. I have the forms for ATF and want to convert it to a SBR. My question is, should i purchase a full upper or can i just put in a 10.5" barrel? Do i have to change any of the operating system if i just swap the barrel out? Will it fit my current hand guard. This is my first SBR build. Or do i need to purchase the full upper and throw that on my RRA lower. Also for the ATF do i just supply the SN from my lower and once approved buy the SBR upper or barrel?


January 31, 2011, 07:10 PM
I might be wrong but i think you can use your carbine length gas tube. The hanguards might work..i'm not positive on that one. But yes you should be able to change out your barrel, use the existing gas tube, and you'll need to add a gas block. It might seem easier right now, but are you wanting to get rid of your RRA and just have a SBR? If your not i would just build or buy another upper.

I can't answer for the ATF forms haven't gotten to fill mine out yet :(

January 31, 2011, 10:04 PM
10.5 and 11.5" barrels use a carbine gas system, and complete uppers (which is easier on so many levels) are usually set with a front sight post and carbine handguards

January 31, 2011, 10:07 PM
Would be way easier to buy an SBR upper from BCM.

Willie Lowman
January 31, 2011, 10:08 PM
SD Chop, you use the serial number on your lower for your form 1 to the ATF.

You can change out the barrel in the upper that you have if you like to tinker around with your gun. It would be much easier (but more expensive) to just buy a 10" upper.

January 31, 2011, 11:37 PM
thanks for the responses. I was in question about the gas systems. Not new to ar platforms just have not come across this task yet. Depending on how i map this out cost wise, i would rather just buy the new upper assembly. Another question is if i choose to add a suppressor do i have to pay the tax stamp again even after paying/registering it as a SBR. Thanks fellas

January 31, 2011, 11:54 PM
From what i've read you'd have to pay the tax on the suppressor once and the SBR once. But i'm not that familiar. But yeah i would run suppressed for sure.

Willie Lowman
February 1, 2011, 01:10 AM
If you buy a silencer, it gets it's own tax stamp. Once you own it, you can move it from one host firearm to another.

mr renwick
February 1, 2011, 07:22 AM
Sorry I don't have the website available but I found Daniel Defense 10.5 and 11.5 striped uppers for $329. I will try to round it for you.

February 1, 2011, 03:06 PM
You might want to post your question in the NFA forum. You'll get answers from the folks who have been there.

As an aside, I recently SBR'd an MKE 94K to make a PDW clone and I couldn't believe how easy the process was. The wait time was just over 100 days including a bunch of fall holidays.

Good luck!

February 1, 2011, 07:16 PM
Thanks, im gonna post it there as well. Want to do the build right mechanically and not have ATF knocking on my door for paperwork also!