If you were to use an adjustable gas block in combination with a VLTOR A5, would you first tune the gas and then play with buffer parts or vice versa?
If you were to use an adjustable gas block in combination with a VLTOR A5, would you first tune the gas and then play with buffer parts or vice versa?
The buffer can usually be selected first and then the gas drive adjusted for proper operation.
The standard A5H2 at 5.4 oz is a great weight for nearly any configuration.
I have a Syrac GB & an A5 RE on my 11.5" SBR. In my experience, the adjustable GB almost negated any real "need" for the A5. Once I set the Syrac to where it needed to be, the A5H2 was perfect.
First off, I prefer dedicated porting any day of the week over adjustable gas blocks. If an adjustable gas block is used, port it to the the most normal use with the standard A5H2 buffer for that combination. You can add or remove reciprocating mass when major changes happen, silencers, ammo, etc.
With an adjustable gas block, you first set the rifle up with the proper buffer, spring and ammo. Then you fine tune the gas. This keeps the gas exhausted by the carrier to a minimum helping to keep the air around your face clear. This makes the adjustable gas block a better option if you are going to switch between shooting suppressed and unsuppressed. The irony is, an adjustable gas block is useless unless the gas port is too large to start with.
This by no means implies that an adjustable gas block is necessary to have a well tuned AR. Without an adjustable gas block, it's essential the barrel has the proper diameter gas port for a smooth running rifle
I don't mind a little extra weight towards the rear of the carbine, so I use the heaviest Vltor buffer, the A5H4. This gives lower initial bcg velocity for the same initial energy. The lower initial bcg velocity makes unlocking and extraction a bit less violent, and makes them occur at a bit lower chamber pressure.
Then I tune the gas block so that the bcg barely locks back with the MGI recoil spring. When used with the A5 system, this spring stores 20-30% more energy in the fully compressed state than the milspec rifle spring. Then I swap back to the milspec rifle spring (I like 17-7).
This gives me an energy reserve that I estimate is equal to that in the milspec carbine set-up, but with a slower bcg (lower cyclic rate) due to the ~30% larger bcg/buffer mass.
Obviously this method does not lead to the smoothest recoil pulse, since the buffer is striking the aft end of the receiver extension with some force. But I think it's worth it to get the mil-spec energy reserve.
Interesting approach.
Rather than swapping springs, I've always done lockback tests with a loose/floating hold.
If the weapon functions in free recoil, it should also function with any type of firm shoulder hold.
*****
The other aspect to buffer selection is the "nose dive" on return to battery, which increases based on spring strength and buffer weight.
IMO, the 5.4 oz A5H2 is ideal for most configurations.
I don't have an adjustable gas block on any of my rifles, so I do the buffer lock back tests as stated above, but that is mainly because that is my only option.
I think it is fairly common practice to do coarse adjustments first and fine tune from there. You only have so many options available with the buffers so start there and tune with your gas port from that point. I don't know that there is an absolute correct way of doing this as long as the end result is a rifle that functions with a wide selection of ammo.
ETA: Hopefully someone chimes in with the absolute best way, with solid reasoning behind the approach. Learning new stuff is great.
I haven't kept up on this thread, but I've been able to tune my rifles with buffer changes. I use a standard carbine receiver extension (as opposed to the A5) and I had or bought an carbine buffer, an H, ST-T2, and H2 buffer. Then I tried them out with the weakest ammo I use up to the good 5.56 77Gr stuff. I note subjectively the feel of the rifle, where the brass lands, and what condition the brass is in. Then I pick which buffer works best. BTW I use the SpringCo 'Blue' spring in most rifles. And I end up using the H2 buffer in most rifles.
I never ever have cycling problems, but I also credit part of that to the fact that I use good parts and primarily BCM BCGs.
One rifle that is different for me is the one with the BCM BFH LW 14.5" Mid-length. In that I use a standard carbine spring and an 'H' buffer.
BCM = Good Stuff