The Silent Captured Spring Gen II from JP Enterprises is a fantastic innovation for the AR platform. It is a replacement for the buffer and buffer spring that combines modular buffer weights with a spring and guide rod, similar to the system used in the 1911. The guide rod keeps the spring from contacting the inside of the buffer tube as it compresses, eliminating the spoon over a cheese grater sound and feel common to ARs. The grating and vibration are all but eliminated, resulting in a drastically smoother feeling and sounding rifle both under recoil and when charged manually. While this might sound like a somewhat minor change, the overall effect is impressive. Aside from the improvement in tactile feedback, felt recoil is reduced somewhat, and the system allows the rifle to be tuned for different uses and configurations by changing out the springs and weights for heavier or lighter ones.
The Silent Captured Spring is available in five versions designed to fit small and large frame receivers (with a heavy version) of each, and one made specifically to function with pistol calibers. The standard spring (JPSCSII-15) fits small frame receivers with a carbine receiver extension. An included spacer allows the spring to be used with rifle length receiver extensions. The large frame version (JPSCSII-10) fits AR-10 sized receivers. Both the small and large frame versions are available with alternate spring packs (5 for the small and 3 for the large). Changing out these springs allows you to customize the spring resistance of the buffer to tune your rifle. In addition to the alternate spring packs, JP sells tungsten replacement weights that can be installed to increase the buffer weight (these are the same weights used in the H2 versions, so if you have a standard weight SCS you can change it to a H2 by switching out the weights).
Both the small and large frame versions come with an extension that allows the system to be used in a rifle length buffer tube. It is a short piece that is installed behind the guide rod and brings total length to the correct measurement for a rifle buffer tube. Due to the differences in specs between manufacturers, some buffer tubes are longer than others, causing a slight excess space between the SCS and the internal end of the tube. JP has said that the simple solution to this issue to to place a quarter or item of similar thickness (0.069″) into the tube behind the spacer and spring assembly, which will bring the components into the correct position and eliminate potential rattle.
Installation is a simple matter of removing the old buffer and buffer spring from the existing receiver extension and inserting the silent captured spring into the tube. The buffer retainer plunger and its spring are not necessary when using a silent captured spring. If used in a rifle length receiver extension, the included spacer is installed in the tube first, followed by the SCS.
Fit and finish are both flawless. JP consistently produces some of the best machined components available. Movement between the assembly components is exceptionally smooth. Each piece fits together extremely well, with no slop or play in any area. These small tolerances are sure to contribute greatly to the longevity of the system, and are a testament to the machining and quality control at JP.
The Silent Captured Spring is currently in its second generation of development. Functionally, the first and second generations are nearly identical. The second generation replaces the original steel guide rod with an aluminum version for a weight reduction. The only other major difference between the two is that the first generation uses a 1/8″ hex wrench for the take-down screw, while the second generation uses a 3mm hex wrench.
For testing, we installed the SCSII-15 in a Rock River LAR-15 chambered for .223 Remington. Over 1,500 rounds fired, wear to the SCS was minimal. Very minor cosmetic scratches could be seen on the guide rod and forward bearing surface of the weight system, but nothing that approached affecting functionality. The plastic bumper had some slight bulging, but no structural damage. The SCSII-10 was tested in a MEGA Arms Maten .308 Win. with similarly negligible results, although only 300 rounds were fired. The forward bearing surface did suffer one moderate ding, from where we assume a piece of debris became lodged between the bolt and buffer weights. Again, this had no noticeable impact on function whatsoever, and had little to nothing to do with the component itself. Replacement bumpers are available from JP for $8.95-12.95.
Because the guide rod of the SCS passes through the bolt during cycling, there must be adequate clearance. The guide rod requires an internal diameter of .530″ to operate correctly. Mil-Spec bolts have .625″, and will function without issue. Documentation from JP states that the bolts that they have found to be incompatible are the older PWS MOD1 designs, as well as some 9mm bolts. In order for the guide rod to not contact the firing pin during operation, the blot carrier channel must be a minimum of 3.75″ deep. The HK 416 is incompatible with the SCS2-15, and the SCS2-10 will not function with the DPMS GII or the Remington R25. Always make sure to check that your rifle will operate without issue before firing, as the design of different guns changes regularly and new models are constantly introduced.
JP sells most of the components of the Silent Captured Spring as replacement or modification parts. Because of this, it is possible to convert a standard weight SCS to a H2 version, or to change a spring system between AR-15 and AR-10 configurations. The same guide rod is used, and the spring, weights, and bumper are switched out for the appropriate ones. Bumpers cost $8.95-12.95, spring packs $24.95-39.95, and weights for $7.95-$24.95. Replacement spacers and O-rings are also available for $7.95 and $4.99, respectively.
The only negative about the Silent Captured Spring is the price. The JPSCS2-15 is the cheapest option at $139.95, and the most expensive is the 9mm short stroke version for $209.95. While certainly expensive, the SCS has enough of an impact on the feel of the firearm that it is installed in to make it well worth the price in our opinion. We are happy to award the Silent Captured spring with our Editors Choice award, and will be replacing many, many buffers and springs in our personal guns with this fantastic product.
If $139.95 for a buffer system seems too expensive for you, check out the Custom Centerless Ground and Polished Operating Spring ($19.95-22.95), also made by JP Enterprises. It is a well engineered replacement for the standard buffer spring. While the effect is not as noticeable as that of the SCS, it does improve the sound and feel of an AR at a fraction of the price.