You can use either carbine tubes with carbine buffers or rifle-length extension tubes with rifle buffers. It doesn't matter, as long as the recoil spring/buffer combo balances out with your gas system.
You can also use an A5 system, which is in the middle.
I actually think the Magpul ACS is one of the ideal stocks for balancing the weight of a longer barrel, because they have a bit of weight to them, if you are going carbine stock.
Here is a 20" barrel with the VLTOR EMOD. This gun balanced out very well.
![[Image: 2015-10-09%2020.42.42_zpsges3e9bb.jpg]](http://i1085.photobucket.com/albums/j422/LRRPF52/2015-10-09%2020.42.42_zpsges3e9bb.jpg)
You can also use an A5 system, which is in the middle.
I actually think the Magpul ACS is one of the ideal stocks for balancing the weight of a longer barrel, because they have a bit of weight to them, if you are going carbine stock.
Here is a 20" barrel with the VLTOR EMOD. This gun balanced out very well.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com