Top: Enidine w/ Shrike Spring and custom delrin plug
Middle: Vltor A5 w/ Vltor supplied spring which is an M16A2 rifle stock spring
Bottom: Standard H2 buffer in standard carbine spring
Looking back at my notes, I did test the middle setup in my Shrike and got a RoF of 602 RPM. I didn't fire it much. Just enough to do some 10 round bursts to get RoF. M855 ammo in all testing.
Below are some of my notes on buffer weights.
I never went heavier than the standard Vltor A5 buffer (5.4 oz) in the Shrike in fear of another carrier breakage.
Which is why I did the Enidine setup.
I've got a bunch of different buffers and springs I use for other M16 configurations. I just have only used, the H, H2, Enidine and very little use of the Vltor A5 standard with the Shrike (just to get RoF as mentioned above).
Below is information I had in one of my spreadsheets of some of my buffers I weighed. This is for my own reference. I'm not saying this is what these buffers are supposed to weigh. Just what I weighed mine at for my own testing purposes.
Spikes T2 4.1
Enidine Hydraulic 4.2
Steel AAC (current production)5.3
DPMS 2 Piece Mechanical 5.4
AAC CS Old w/ One Tungsten Weights 7.4
AAC CS Old w/ Two Tungsten Weights 9.4
Vltor A5 Buffers