[FIGHTWITar's]

Hey!
new to forum, had a question for u sbr guys. Im looking into adco cutting and rethreading my 16' to 10.5. I understand that the gas port needs to be opened as well to compensate for the shorter barrel length. I also want to be able to run a back up 16' barrel as well. My question is. Is this possible? would the 10.5 run on he 'S' mode and 16' on the 'U' mode?

 

[DSM]

If you want a 10.5" ACR barrel there will be a little more to it than just cutting the barrel back. The standard barrel is mid-length gas so cutting it back that short would be problematic at best. You'll need to go to a carbine gas length barrel and modify the factory ACR gas piston to fit the shorter system. Since that mod would be permanent you'd need to use a 16" barrel that was also carbine length gas and swap over your parts (if you don't have an additional barrel). That said, I don't know that anyone outside of BM and/or Remmy has any experience with carbine length gas on 16" barrels to know how to tweak the port size to work.

I don't really understand what you're asking in terms of one barrel running on "S" and the other on "U".

 

[kjsl105]

10.5"

Hey FIGHT,

Welcome to the forum. Bigdog did the 10.5" on his ACR, this should help:

http://www.acrforum.com/forum/showthread.php/348-10.5-quot-sbr-acr!?highlight=bigdog

 

[FIGHTWITar's]

Thanks for he help!
so just to be clear. Id be unable to run both a 10.5 and a 16' barrel on the same rifle due to the gas system being perm. modified for the 10.5 correct?

 

[kjsl105]

Correct,

From what I understand the Op Rod would have to be cut down to accomodate the 10.5" Barrel.
What you might do is just keep your factory barrel and components in tact and purchase an extra system to modify.
That would allow you to change them over when needed. $569 shipped from Bushmaster but their order dates are finicky.

 

[DSM]

Thanks for he help!
so just to be clear. Id be unable to run both a 10.5 and a 16' barrel on the same rifle due to the gas system being perm. modified for the 10.5 correct?

If you had complete barrels then you could run whatever you wanted of course.

 

[bigdog2003_99]

If you had complete barrels then you could run whatever you wanted of course.

this is true, if you are going to only have one gas system between the 2 barrels then you will have to run a carbine length system on the 16" barrel too

the problem with swapping the gas block between both barrels will be the flash hider, especially if you are running a suppressor like aac for instance which needs rocksett to sit for 24 hours each time applied