Difference in receiver extension length?

[ike838]

Thanks for the info. I didn't know that there that many buffer weights for the A5 system. Still wondering if the adjustable gas block will make a carbine extension as soft shooting as the A5. Carbine extensions seem to be quite a bit cheaper than Vltor ones and if I can just dial the gas back and get the equivalent result of the A5 system I could use the savings on other areas of the build.