TBF Posted July 5, 2004 Share Posted July 5, 2004 The JP LMOS looks like it would work pretty well ( light weight carrier ). Less gas, less weight = less percieved recoil Makes sense to me . But G. David Tubb CWS system ( which adds weight to the carrier via an insert ) also claims to do this. Less momentum to the bolt carrier due to less bolt carrier speed ? I see this as making less sense , but I ain't no engineeer. So what's the real deal ? Help appreciated. I have not tried either one of these , let alone compared them side by side. Travis F. Link to comment Share on other sites More sharing options...
Zak Smith Posted July 5, 2004 Share Posted July 5, 2004 Less momentum to the bolt carrier due to less bolt carrier speed ? Momentum is mass * velocity. Ones goes up, the other down. From zediker.com: The addition of weight to the carrier slows its rearward start upon action cycling. Technically, it increases the moment of inertia, but that simply means that the rifle will stay "locked" a little longer. This additional time reduces the influence of pressures on the cartridge case and also softens rearward carrier movement. The result is much better brass life, fewer "pressure problems," and greater flexibility in velocities attainable using all bullets &emdash; especially the heavier bullets used in High Power Rifle competition. There is also noticeably less rifle movement during firing and longer parts life from a softer recoil pulse. The primary benefits he lists are accuracy-oriented, due to increased lock time. As a side-benefit, carrier velocity is slowed and he claims the rifle recoils "softer", whatever that means. Note that just adding a weight to the gun will make it recoil "softer." The J.P. system is designed specifically so you can retain your sight picture while double-tapping targets at 3Gun ranges (0 - 300 yards). The goals of the two systems are different. -z Link to comment Share on other sites More sharing options...
George Posted July 6, 2004 Share Posted July 6, 2004 Additional point to the facts that Zak mentions. In High Power rifle competition, no one uses muzzle brakes and the recoil damping of the Tubb CWS does soften the recoil impulse of the very hot loadings they use. The muzzle brakes in use in IPSC do a more effective job of removing recoil pulse than a CWS ever will. After an effective muzzle brakes stills the rifle movement, the LMOS then adds the reduction in cycling impulse that only really becomes noticeable after the main recoil impulse is removed. The recoil impulse and the action cycling pulses exert different forces on the rifle. The effect of the LMOS is mostly masked by recoil with no muzzle brake in place. The CWS would increase the cycle pulse sight dance if added to an AR that already has an effective muzzle brake. Most AR High Power shooters take the rifle weight way up (14 lbs +) for a series of reasons, recoil being just one of them. -- Regards, Link to comment Share on other sites More sharing options...
uscbigdawg Posted July 6, 2004 Share Posted July 6, 2004 The JP LMOS is very cool and works extremely well. I didn't run it at Nationals as it was still relatively new in the rifle at didn't want to risk the match on it. Since, I've been doing some practice with it and it is incredible. The reduced mass greatly increases the rifle's tracking on target. Rich Link to comment Share on other sites More sharing options...
TBF Posted July 7, 2004 Author Share Posted July 7, 2004 Thanks for the info. I suppose comp vs. nekkid barrel recoil would play a part in the choice too. I am building a comped iron sight gun. Question : If the JP LMOS is used with the standard front sight base ( no adjustment ) will it batter the living crap out of something ? I am thinking the answer is yes. Travis F. Link to comment Share on other sites More sharing options...
Zak Smith Posted July 7, 2004 Share Posted July 7, 2004 Although I have the adjustable gas block on my CTR-02 (with LMOS), I just run it wide open all the time. More gas makes the bolt carrier run faster. -z Link to comment Share on other sites More sharing options...
George Posted July 7, 2004 Share Posted July 7, 2004 If the JP LMOS is used with the standard front sight base ( no adjustment ) will it batter the living crap out of something ?I am thinking the answer is yes It Depends. The LMOS is an alloy carrier, so you need the JP speed hammer, or special profiling of the regular hammer (better to just get the whole JP trigger group). The alloy material will get chewed up badly by a standard hammer. The LMOS uses a shortened spring and damper setup because it needs less impetus so it would be “sprung” more than it needs to be thereby defeating the purpose of the LMOS by reducing cycling violence. It might also be less reliable than damaging if the bolt carrier doesn’t travel full stroke, or gets going too fast the other way. So you can’t just drop a LMOS upper on any lower, or a new carrier in any upper without changing a few things. The gas block is just a tuning point and will not hurt things if run WFO. I don’t run my JP gas block WFO, but I do open it up enough to function with 55gr ball at about 3050 fps. This gives me lotsa‘ bolt speed with the 180 and 200 PF heavies that I really shoot, but will still function reliably with most common ball fodder if it’s snappy stuff. If you detune the gas to just barely operating with a specific loading, the LMOS bolt carrier does lack energy and will probably give you trouble if run dirty, or the mags drag, or? -- Regards, Link to comment Share on other sites More sharing options...
Zak Smith Posted July 7, 2004 Share Posted July 7, 2004 My CTR02 was shipped with the L.M. bolt carrier, but the rifle-length operating spring and buffer. Go figure. As long as I put a couple drops of lube into the holes of the bolt carrier and run it back and force a little bit, it seems to run reliably. -z Link to comment Share on other sites More sharing options...
George Posted July 7, 2004 Share Posted July 7, 2004 As long as I put a couple drops of lube into the holes of the bolt carrier and run it back and force a little bit, it seems to run reliably Hi Zak, Thread drift> I was getting a sticky bolt after about 200 rounds until I started putting a few drops of lube in the bolt holes about every 100-150 rounds. If I do that it stays free and I can go 5-600 rounds without a thorough upper clean. I remember Kurtm mentioning in a thread somewhere that it seemed to be unique to the one piece macfarland style gas ring JP puts in them. He said that he went back to the old 3 piece ring set and it stopped getting sticky bolt syndrome. Thread back> My CTR02 was shipped with the L.M. bolt carrier, but the rifle-length operating spring and buffer. Go figure I wonder if it is a later version and just a softer spring, mine is one of the first CTR-02 uppers out the door and that might be different now. If it is a standard rifle spring and buffer, that might explain the bolt being slow without it being WFO at the gas block. Hmm! -- Regards, Link to comment Share on other sites More sharing options...
Zak Smith Posted July 7, 2004 Share Posted July 7, 2004 I don't know about the spring strength. When using normal bolt carriers and gas blocks, I prefer the recoil impulse I get from a short carbine stock. I noticed this even more dramamtically in my AR10. -z Link to comment Share on other sites More sharing options...
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