msrx-usa.com
L'il Helper
(patent pending)
The MSRx-214 L'il Helper is a special purpose system, designed to enable forced reset safety devices and inhibit bolt bounce.
AR-10 Buffer
Combine the MSRx-214 with an AR-10 carbine buffer and spring, in the A5 style buffer tube.
The total length of this combination is 4-3/4".
For AR-9 blowback PCC's with A5 style, or J.R.C. buffer tubes.
If you already own an AR, you may have the buffer and spring.
AR-15 Buffer
In a Just Right Carbine buffer tube, pair the MSRx-214 with any AR-15 carbine buffer and spring.
The total length of this combination is 5-1/2".
The 411 about FRS/SS
The MSRx-214 (buffer and spring) has been tested and proven to function with the Atrius FRS and G.M.R. super safety devices when paired with AR-10 carbine companion buffers (weighing from 3.8 ounces to 5.4 ounces) and a 28-coil AR-10 carbine spring in an A5 style buffer tube, as well as AR-15 carbine buffers (weighing from 3.0 to 5.7 ounces) and an AR-15 carbine spring in the J.R.C. extended buffer tube. The solid steel buffers that we tested as companion buffers performed no differently than the buffers with sliding weights of similar mass.
There seems to be a notion that it takes at least 10 ounces to run a forced reset selector or super safety device, but we've had 100% function with a total buffer system mass (MSRx-214 + companion buffer) as low as 5.8 ounces, with no indication of bolt bounce. The significant differences are rate of fire and felt recoil. As a rule, the heavier the companion buffer, the slower the rate of fire and the softer the recoil.
Sliding Buffer Weight
The MSRx-214 L'il Helper buffer contains a 1.5x hard cast sliding buffer weight, which satisfies that requirement of the forced reset selectors and super safeties. Testing has shown that we can use a (cheaper) solid buffer rather than fork out the big bucks for tungsten.
The abbreviated carbine spring is approximately 1.5x the length of the tail, which allows the L'il Helper to become one with the companion buffer when compressed inside the buffer tube, all the while providing an added measure to inhibit bolt bounce.
When fully compressed, behind the bolt, both buffers act as one unless there is a bolt bounce occurance.
A5 Style Buffer Tube
The MSRx-214, along with an AR-10 carbine buffer 28-coil carbine spring, in an A5 style extended buffer tube.
J.R.C. Buffer Tube
The MSRx-214, paired with an AR-15 carbine buffer and spring, in the Just Right Carbine 8.5" buffer tube.
Bolt Stop Clearance
Both the L'il Helper and Big'r Brother system buffers are designed to provide ~3/16" of clearance behind the bolt stop when the bolt assembly cycles fully to the rear of the buffer tube. This may vary slightly depending on buffer tube and lower receiver.
You can fine tune the total package weight with a simple change of the companion buffer.
A solid AR-10 carbine buffer (3.8 oz) and the MSRx-214, while it may seem on the light side, has been tested and proven with the Atrius FRS as well as the G.M.R. super safety, in an A5 style tube.
The MSRx-214 buffer and spring will add 2.8 ounces to the overall weight of your recoil system. Combine with the carbine buffer (and appropriate spring) of choice for the desired total mass.
A solid AR-15 carbine buffer (H3, 5.7 oz) combined with the MSRx-214. This pair has been been tested and functions with both the Atrius FRS and the GMR super safety in the J.R.C. 8.5" buffer tube.
A word about AR-10 carbine buffer springs!
If your bolt doesn't cycle far enough to clear the bolt stop, or if recoil seems excessive, this may be why.
We do offer 28 coil AR-10 carbine springs in the online store.
Having tried a few AR-10 carbine springs while working on the L'il Helper and A5 style tube it was surprising how they are all over the map. These springs were all sold as AR-10 carbine buffer springs, yet none are the same length when fully compressed.
The spring on the left has 30 coils of .071" wire and when compressed, fails to expose the bumper of the buffer.
The buffer spring on the right also has 30 coils, but thicker wire @ ~.075", and is far too long for proper function.
The middle spring has 28 coils of .070" wire, exposing the bumper of the buffer when fully compressed, which is a necessity for proper cycling.
So, count your coils, because spring bind is not good.