A5 buffer setup using A2 extension with spacer?

[Caligula36]

Im in process of planning out a 6.5 Grendel AR that will have a fixed stock, either the Magpul PRS or Fab RAPS. I would like to use a rifle length system as I already have the spare parts, and would like to try a low weight carrier and buffer setup. My intention is to try to make a A5 buffer system with a rifle length tube. Based on what I have found online:



Carbine extension: 7 - 7.25"

A5/SR25 extension: 7.75 - 8"

Rifle extension: 9.5 - 10"



Sources:

[URL unfurl="true"]https://www.ar15.com/forums/ar-15/Rifle-Buffer-Tube-Question/4-770078/[/URL]

[MEDIA=reddit]AR10/comments/p5mutt[/MEDIA]



So does it a fair assumption that putting a ~2" delrin spacer within a rifle tube would give it effectively the same internal depth as an A5 extension?



Brownells has some premade options that could work, however they may add an extra 1/2" or more to convert into a carbine length rather than A5.



[URL unfurl="true"]https://www.brownells.com/gun-parts/rifle-parts/rifle-stocks-parts/ar-15m16-buffer-spacer/[/URL]

[URL unfurl="true"]https://www.brownells.com/gun-parts/rifle-parts/rifle-stocks-parts/ar-15-a2-stock-spacer/[/URL]

[ar15barrels]

The full length A2 spring and buffer are even BETTER than an A5 as the A5 uses a carbine spring which has a higher spring rate than an A2.
A2 makes the smoothest running rifle because of the lighter spring and heavier weight.
If you want less weight than a regular A2, take apart an A2 buffer and replace steel weights with aluminum or delrin spacers.

[Caligula36]

The full length A2 spring and buffer are even BETTER than an A5 as the A5 uses a carbine spring which has a higher spring rate than an A2.
A2 makes the smoothest running rifle because of the lighter spring and heavier weight.
If you want less weight than a regular A2, take apart an A2 buffer and replace steel weights with aluminum or delrin spacers.

Thanks for the response! This was part of what I was wondering. I understand that the length of compression whether it be a carbine or rifle system is about the same, about 4in. I think the two main advantages of the A5 system, from what I've read in various posts, is the greater spring tension from a rifle length spring compressed in excess of what is found in a A2 extension. Secondly, the A5 buffer having a internal spring which biases the weights forward within the unit.

The main reason I wanted to try a A5 system is the availability of lighter buffers, as I am going to be using a lightweight carrier and adjustable gas block.

Are the buffer weights for a carbine the same as a rifle carrier? Do you have a recommendation of where to get these? Replacing the steel weights within a A2 carrier with aluminum May provide the weight I am trying to achieve.