[miamivicedade]

Hi All -

How do I know what size rail or handguard to put on my AR. Carbine, mid-length, etc.

I got a Sig M400 SRP.

Thank you in advance.

[GI_Jared]

looks like it has a carbine length gas system. So if you are not changing out the gas block then you would need to purchase a carbine length rail system/free float tube.

[miamivicedade]

Thank you!