Ugh, here we go again... same bat time, same bat channel...err forum.

A few people here need to read on what Dr. Roberts has posted about his testing with the piston guns, from what I read the HK has performed best of all. That may have changed recently but that was back in Mid Spring 2008 when I read this.

I'm not saying LMT and LWRC or the Rec-7 since it too is piston, did not fare well, the HK, last I checked from a reputable source (versus us unknowns on the net) said the HK was showing best overall. That again is dated info and may not be the most up to date.

Text from "verboten" site

Credit goes to SMGlee

"Following the success of British SA80A2 project that HK did for British MoD, HK carry that momentum to the M16 platform as the next logical choice. As soon as the HK 416 hit the military market, been a favorite combat platform for the elite of the elites, and a much desired weapon in the US civilian market with street prices that reached the astronomical 5000.00 for a complete barreled piston upper, HK recoil buffer and buffer spring.



While due to some political restrains, HK was unable to sell the HK 416 on the US soil for the civilian market, it created a void for others to follow. First into the fold was LWRC, which has been one of the few successful piston systems that can match directly against the HK 416 system in turns of performance and durability. Later POF join the fray and soon a salute of cottage industry risen to fill the new piston craze. From drop in system to conversion, so far only LWRC, POF and newcomer PWS has proven to be a viable system.

This year LMT pushed out their long under development piston system based the MRP (Monolithic rail platform). LMT has had a piston system from as far back as the SCAR solicitation, but due to production schedule/availability, timing and LMT ‘s desire to come out with a system to topple the rest, resulted in the delivery of the system until now. The standard direct gas MRP has been the Ferrari of all M4/M16 platforms with features such as quick change barrel, solid one piece rail platform, and now a piston system. Most of the piston system on the market including the HK 416 has a much different recoil impulse than the direct gas guns, the felt recoil is more of a sharper jolt. The HK 416 recoil impulse is not as smooth nor is it as soft as the direct gas guns, but for reliability, there is no matching the capability of the HK. LMT MRP in another hand, it is about as smooth and as soft recoiling as the direct gas gun, in comparison to the HK 416, the LMT piston system are far more like the recoil of the direct gas guns than anything I have shot recently, including the LWRC, POF, and PWS.







We set up the LMT piston system with just the basic, EOTech 556, Midwest Industry flip front and rear SPLP sight, TangoDown rail panels and vertical grip. The host lower has a H2 buffer with standard recoil spring. All testing was shot using the latest in magazine technology, the new TangoDown ARC polymer magazine.



The accuracy of the piston MRP is also on par to the hammer forged barrel on the HK 416. We shot prone from 100 yards, the scoped used was a Leupold MR/T 2-8X36 with illuminated mil-dot mounted to a American Defense Manufacturing 30mm quick detachable mount. Both guns shooting a 1-2MOA group with Hornady 75GR TAP, about 2-3 MOA with Lake City M855 and also M193. We also ran Wolf but that ammo was more for reliability testing than actual accuracy. The numbers posted by the LMT MRP are on par with any combat carbine currently fielding. I believe if I used a match trigger for the testing, the accuracy results would be slightly better.

As far as reliability, the HK has proven itself time and time again on the battlefield; can the LMT match its pace? As HK are already a proven system, we concentrated on the MRP piston. We shot 500 rounds of wolf, 500 rounds of M193 and also 500 rounds of M855 plus a saluted of reloads and factory ammo from various shooters at the training session that day. The total round count came to approximately 2000 rounds during the day. The LMT piston worked flawlessly. And the internals only took a simple wipe down to get it clean. However due to Wolf ammo, we had to scrub the throat, chamber and also the bolt head to get rid of the red sealant common on the Wolf ammo.







HK 416 utilize a lot of proprietary components, from barrel, barrel nut, bolt, bolt carrier, to firing pin, none of this is interchangeable with the Direct gas guns, and you would have to run the HK buffer and spring in order to keep the recoil impulse in check. But with the MRP you actually have a few more common parts to the DI gas gun than the HK, you can still run the standard bolt and firing pins inside the MRP which are some of the more commonly replaced parts in the AR system. With the HK, you would pay a high price for the armor’s tool just to remove the barrel, with the LMT, two torque screws which keep the barrel secured in the monolithic rail platform. For those of us that are not on a government budget, the MRP is definitely a lot easier to service than the HK 416.











HK piston is a top loading system, although the rail system on the HK 416 is supposed to return to zero, a lot of operators I spoke with never like to remove the rail to clean the piston since re-zeroing the PEQ15 are very time consuming task. LMT MRP is a front loading system; all parts are easily accessed by removing the front gas regulator plug, so you do not have to remove the rail system to access the piston. Also the plus is adjustable for standard fire and suppressed fire; this is a major plus for those that run suppressed guns. We had the opportunity to shoot both system with the excellent AAC M4-2000 and the result was interesting. With a suppressed piston system, it is naturally much louder than a suppressed DI gas gun due to the gas regulator releasing excess gas. The LMT MRP shot slightly quieter than the HK 416. We measured with a studio quality sound meter placed at the shooter’s left ear. The HK piston system shot approximately 1.5dB higher than a DI gas gun, but with the LMT the sound suppression came within 1 dB of the DI gas gun. Both guns ran higher cyclic rate when suppressed, but it was still slower than a Colt M4 suppressed.





LMT MRP piston system, it is on par with the weight of the HK 416, which is heavy compare to a Direct Gas M4, but you give up in turns of weight to gain the ultimate reliability in an AR system. But With the LMT MRP piston system, you have a platform (so far) that is just as reliable as the HK 416, but at half of the cost (street price LMT at 1400.00 vs. 4000.00 for the HK 416), less recoil, softer shooting platform with slightly more common parts than the HK 416. Only remaining question is how reliable is the piston system design? This will require more than just the 2000 rounds I shot in a day, I will have to keep this gem and run a lot more rounds through it. I plan on taking this gun with me to Larry Vicker’s carbine class in South Hill, Virginia in a month time."

I wish I could host all the photos, but this is a good read.