A&S Conversions
UZI Talk Life Member
To me, there are two very different applications and some assumptions. A semi auto PCC competitor will be looking for recoil management and follow up shots. There would tend to be a tendency for quick cycling and recoil management.
There is a balance between enough spring pressure to mitigate rearward bolt speed, end of travel recoil transfer, and spring strength to cycle the action. There are two basic ways to slow cyclic rate in a blowback system, spring rate and bolt mass. So the PCC competitor will be looking for the fastest cycle rate to lower split times. So that application will focus on higher spring rate to soften end of cycle recoil mitigation and quicker cycle time. A hydraulic buffer with a stronger hydraulic cycle pressure would be preferred, especially when the stronger spring drives the bolt faster into battery. So that stronger valve/spring internal mechanism of the RB5007 or RB 5015 would be beneficial.
The full auto shooter is actually looking to slow the cyclic rate. As long as the spring is strong enough to strip the top round from a fresh magazine softer recoil spring will tend to slow cyclic rate. That is why the flat wire spring is recommended for full auto.
The other difference between the PCC competitor and full auto shooter is the release of the hammer. The semi auto competitor fires the follow up shot after a complete cycle of the bolt group and a function of the trigger. The trigger can not be actuated until the bolt group has completely cycled. The M16 system, in full auto is designed to release the hammer before the bolt is fully in battery. If timing is perfect, the round will ignite at the exact moment the round is in complete battery. The design has some tolerance for a little delay or premature ignition. The heavier valved PCC buffer is slower to absorb the forward motion because in the PCC application it has the time to absorb the bolt bounce from being fully into battery before the hammer can be released. A full auto application doesn't have the time for stronger valving. So the valving should be weaker to allow more of the mass of the buffer to be in place to absorb the next round's recoil. The full auto application just doesn't have the time that the semi auto system has to cycle. "amphibian" has done a great deal of full auto testing. It is my understanding that the softer spring and valving (additionally the increased mass) of the RB5005 can cycle fast enough for greater benefit in a full auto application.
I am not a mechanical engineer. Given what I know of the systems, what I have expressed makes the most sense to me, that the softer valved/spring system will tend to work better in a full auto application. I would think that the vast majority of Kynshot customers are looking for semi auto applications. That would be why Kynshot would recommend the heavier valve and spring buffers for that 9mm blowback application. I have seen myself that the lighter valve/spring variant is smoother in full auto than the heavier valve/spring variant with all other variables the same. YMMV.
Scott
There is a balance between enough spring pressure to mitigate rearward bolt speed, end of travel recoil transfer, and spring strength to cycle the action. There are two basic ways to slow cyclic rate in a blowback system, spring rate and bolt mass. So the PCC competitor will be looking for the fastest cycle rate to lower split times. So that application will focus on higher spring rate to soften end of cycle recoil mitigation and quicker cycle time. A hydraulic buffer with a stronger hydraulic cycle pressure would be preferred, especially when the stronger spring drives the bolt faster into battery. So that stronger valve/spring internal mechanism of the RB5007 or RB 5015 would be beneficial.
The full auto shooter is actually looking to slow the cyclic rate. As long as the spring is strong enough to strip the top round from a fresh magazine softer recoil spring will tend to slow cyclic rate. That is why the flat wire spring is recommended for full auto.
The other difference between the PCC competitor and full auto shooter is the release of the hammer. The semi auto competitor fires the follow up shot after a complete cycle of the bolt group and a function of the trigger. The trigger can not be actuated until the bolt group has completely cycled. The M16 system, in full auto is designed to release the hammer before the bolt is fully in battery. If timing is perfect, the round will ignite at the exact moment the round is in complete battery. The design has some tolerance for a little delay or premature ignition. The heavier valved PCC buffer is slower to absorb the forward motion because in the PCC application it has the time to absorb the bolt bounce from being fully into battery before the hammer can be released. A full auto application doesn't have the time for stronger valving. So the valving should be weaker to allow more of the mass of the buffer to be in place to absorb the next round's recoil. The full auto application just doesn't have the time that the semi auto system has to cycle. "amphibian" has done a great deal of full auto testing. It is my understanding that the softer spring and valving (additionally the increased mass) of the RB5005 can cycle fast enough for greater benefit in a full auto application.
I am not a mechanical engineer. Given what I know of the systems, what I have expressed makes the most sense to me, that the softer valved/spring system will tend to work better in a full auto application. I would think that the vast majority of Kynshot customers are looking for semi auto applications. That would be why Kynshot would recommend the heavier valve and spring buffers for that 9mm blowback application. I have seen myself that the lighter valve/spring variant is smoother in full auto than the heavier valve/spring variant with all other variables the same. YMMV.
Scott
