Many say that lightweight carriers are not for anything but gamer or fun guns. Maybe they're right. But does anyone really KNOW?

I know aluminum carriers have low lifespans. Not talking about them. Looking for real data, torture tests, etc on lightweight steel and Ti carriers. How do they hold up?

No pure opinions please, but knowledge of any kind of testing would be appreciated.

Thanks!

I don't think the issue is longevity or durability. The M16 has over 16 oz of reciprocating mass and the M4 has a little less. If you reduce the mass of your buffer inserts, you will have bolt bounce. If you use reduce mass without also reducing your gas port diameter, you will have an overgassed rifle. If you reduce the mass, you will have less kinetic energy while loading a cartridge from the magazine.

wordmahn - like you, I wanted to see for myself what were the drawbacks of a very lightweight rifle.  After a lot of reading and research, it came down to lightening the reciprocating action components that appear to be the most controversial.  Some folks have turned their receivers and other components into "swiss cheese" by using puposely skeletonized parts, but in the end, as you already know, barrel, bcg and buffer makes a huge difference in weight.  Like many others, I decided to use components that would be structurally sound in my usage:
1) Not doing mag dumps, prolonged rapid fire, or using select fire (can't afford it)
2) Mostly range shooting, occasional amateur competitions and training classes, but also a useful/reliable home/self defense weapon
3) Something I could carry for prolonged periods on my rural property
4) Something I could qualify empirically by testing to rely my and loved ones lives on (in other words, consistent shooting characteristics/behavior)
5) Something that would be relatively accurate, easy to maneuver, with minimal recoil (muzzle displacement) in a CQB engagement (50 yards and in)

After speaking to a lot of 3 gunners to start, I understood what their goals were and that they also wanted high reliability during a match.  They were all aware of the reliability risks of a lightweight rifle, and a lot of the risk mitigation was the preparation of the rifle and ammo before a match.  All of them knew their rifles inside and out, knew what to expect, and knew how to maintain and tune their weapons.  Based on their experience and help, I built my SBR.  ARFCOM and other sites provided a lot of information, but there were a lot of conflicting opinions that I had to sort out for myself.  

Ammunition is a key to lightweight reliability.  Consistent pressures helps a lot, but leaving a bit of margin in the tuning of a DI action is a key risk mitigation item.  Knowing where your gas settings need to be for the specific ammo you're shooting, suppressed or unsuppressed is a big key.  Reloaders have a great advantage for lightweight action reliability  With all that, using lightweight action components and lightweight barrel, I found that my SBR is ultimately reliable, but I'm also careful with ammo selection and rifle maintenance.  I understand why many in ARFCOM may dispute this, but based on my extensive testing and experimenting, I'm really confident in my lightweight SBR.  It costs a lot of time, money and effort to really qualify high confidence in your gun.  Okay, guys - flame on, I probably deserve it, but I'm sticking to these reasons.

You have to approach it as s SYSTEM. I wrote a piece in the AR BASICS section under light weight bolt carriers on how to do it correctly. Many are reporting excellent reliability and function. I believe it's GTG if done correctly. Is it reliable as a standard, over-gassed, heavy system? Probably not. But if one insists on the absolute best reliability, they should get an AK. Better yet, a bolt action. As always, it's about tradoffs.  

The key to your particular concern is to use an adjustable gas setup of some kind. If you diminish the energy going into the system, you diminish those kinds of problems.

Thanks.

I shoot mulitgun and other competitions. Got many thousands of rounds fired.

I had always used M16 carriers, with heavy buffers until I fired a real gamer LMOS gun. The difference is night a day when shot side by side.
I then built up a LMOS gun for gaming too.

16" midlength with SLR adjustable gas block, boomfab titane titanium carrier, a gutted car buffer (weights removed), and a Springco "hot white" spring.
Adjusted for ammo I never have once had a failure to feed with the rifle. I really think the "it wont feed because of inertia weight blah blah" is just that. blah blah.  

Only failures would come from being overly dirty from extremely dirty environmental conditions at a specific matches. If the rifle malfunctioned it would always be a short stroke stovepipe were the action didn't go back far enough to eject, nor even try to pickup the next round.

Cleaning and maintenance cycle is higher then a plinker gun. This is obviously because being clean it is more reliable (ditto for duty weapons).

Parts wear and breakages happen. I've replace the firing pin retainer many times on both full mass M16 carriers and with LMOS. I switched to a titanium firing pin a few years ago and the retainer pin doesn't take anywhere near the beating it used to.  I don't recall having replaced a firing pin retainer pin since putting in the titanium firing pin.

Other points: I switched out the boomfab awhile ago after the rifle got finicky with no one thing being wrong.  I dropped in the spare M16 carrier with no other modifications and the rifle worked again. I feel even the titanium carriers have a service life that is shorter then a steel carrier.  I'm not metallurgist so I don't know what's what for wear. But chrome bored steel carriers seem to last for ever.
 I recently put a steel light weight carrier in the rifle. So far it has been perfect for me and with that old more steady feel of the other LMOS carrier I had in the rifle.

I wont be going to an aluminum carrier nor switching back to titanium carrier anytime ever. In my opinion they have too short a duty life. To be fair the boomfab lasted 12k+ rounds fired before it go finicky on me.  Boomfab has since stopped making titanium carriers.


For a game gun, go with a quality parts combo that works. In my opinion stick with a steel carrier for longevity. Items wear out, but carriers shouldn't.

Current steel carrier has 1500-ish rounds fired between practice, training, and matches in the past 4 months or so.

The issues I stated are all distinct.

Many using lightweight bolt carriers and buffers successfully is still anecdotal. I would think the US Military and Colt have tested this thoroughly. The buffer on the carbines has been getting heavier as time goes on. There has to be a trade off. It may not matter as much on a semi auto fair weather range gun. If we're talking about a "life and liberty" type rifle, is it worth the 8 oz and recoil reduction?

Good first hand details notgrownup. Thanks a bunch.

I wouldn't go aluminum either. And I have one. I can live with 12K rounds on a BC for a Ti carrier that provides these benifits. I have a V7 but have yet to shoot anything close to that. We'll see how she does.

Thanks again for the detailed, real world information. You gamers provide a wonderful service by giving all this stuff a good workout.

Happy shooting!

I've also done a heavy spring in combination with a lightweight carrier on my BumpSAW.  That has worked quite well for me.  Sprinco Orange spring in my case - it ALWAYS wants to close.

Buffers get heavier because barrels are heavier - that increases bolt bounce.  Reducing carrier weight reduces the need for extra buffer weight with the same barrel weight.


I get zero bolt bounce with my 16" heavy barrel, rifle gas sytem, light weight carrier and CAR buffer.  It usually operates right at 1,000RPM, and I haven't had a bolt bounce/hammer follow issue since I went to the light weight carrier.


The Sharps Reliabolt on the other hand killed it, lol.  Immediate extraction/ejection issues.  I've replaced the ejector and extractor but haven't had any range time since  I'll bring my old bolt next range trip and put it back in if Sharp's replacement parts don't fix it.

For a full auto REALLY hard use gun, no. FA puts a great deal more stress on the system and accelerates problems. For a SHTF gun, I suspect that a moderately, well executed lightweight OS can be almost certainly reliable enough.  

Your other particular concern about less energy to run the system is certainly valid.  Proper gas adjustment, slick coatings, and a good buffer system all help.  Maintenance schedules would need to be tightened. I heard from a gamer who was running a way more radical setup than I would use, and he said his aluminum carrier, ragged-edge, race-gun started getting "finicky" after about 350 rounds. Others said they were doing thousands of rounds with minimal cleaning.  If I only get 350 rounds, that's more than a standard combat load-out, which even Navy Seals almost never run through. I figure there'll be time to clean my fast shooter while the other guys are taking dirt naps.

I'd just like to see some real testing on reliability and wear. Anecdotal evidence may be all we can get right now, but it does help.

Thanks, dude.

I wonder why the Sharps bolt caused a problem? Did you figure it out?

Not sure Im getting the correlation between barrel weight and buffer weight. Maybe a heavier makes the weapon more stationary during cycling and that could exacerbate bolt bounce perhaps.

Haven't heard of people running lightweight OS parts in FA rigs much. I dropped an aluminum BC in an overgassed carbine-gassed stick one time just for fun and it ran like a buzz gun! It must have been like 1400 RPM. It was a blast, but it tore up the carrier. It was amazingly smooth though. If it was sustainable I'd love to set up an area gun like that. Put a H-BAR on there, a Cmag and a heavy bipod and It would be like having a mini MG42.

The setup I detailed in my other write up is a litttle more radical and has been 100% for me so far.  Yes, tuning the spring and perhaps the buffer weight is an important part of doing it well. I'm really thinking that the Vltor A5 adds reliability unless someone is already running a rifle length buffer.

Exactly like that. It was fun while it lasted though. Pity no one has figured out how to affix a hardened plate on that surface. But I suppose it would just fail somewhere else. Spikes said they were on track to build a super-duper one, but then...nothing.

Thanks, Josh.  Your experience is appreciated.

Have you found certain ones to be more or less reliable for you or is that more or less your gut?

wordmahn:  Two of my AR rifles are designed with reduced weight in mind.  One has a Rubber City lightweight steel carrier, the other has lightweight titanium carrier from the same maker. Both use 1 oz buffers with special reduced-strength springs from Taccom.  A standard carbine buffer with the weights removed weighs about the same.

Whenever the weight of the reciprocating parts is reduced significantly, adjustable gas is necessary to keep bolt speed down to specification levels (as measured by case ejection pattern).  I use Rubber City's adjustable gas key on both of these carriers.  They work great, but the result is each rifle is tuned for a specific load, not a problem for most people, but not quite as flexible as a 223-chambered AR with rifle everything (20" barrel, rifle gas, rifle receiver extension, buffer and spring).

FWIW, the rifle with the steel carrier is a 6.8 set up as a military carbine with 16" barrel and Magpul handguards, weight with iron sights is 5 lbs, 13 oz.  The rifle with the titanium carrier is a 6.8 hunting rig with 16" pencil barrel, weight with 2-7x28 scope mounted is 5 lbs even.  Both rifles are utterly reliable and accurate enough.  No perceptible wear.  I don't shoot full auto so bolt bounce is not an issue.  Quick double taps work just fine. - CW

I'm right with you. I've got an adjustable block on my Ti carrier LMOS gun. Adjusted it to lock back on Wolf. Everything else runs great so far. I just wonder if it would hold up to a sustained high volume firing schedule. It sure runs sweet though. Five pound gun that shoots full-up 77 grain BH with almost zero muzzle rise if I hold it right.

The anecdotes are helpful. I just wish I could find some kind of test data. Part of the problem is that the military and military contractors are mostly the ones who provide that sort of thing, and they're testing FA when they do test. I wonder if anyone has done some kind of torture tests on light weight OS, semi-auto guns to give us a better idea of that system's durability and objective reliability.

The ability of that system to reduce muzzle jump and provide much faster shot strings is pretty well known. But the jury seems to be out on whether it's GTG for defensive work. Probably fine for SHTF or light LE purposes, but it would be nice to have a more objective answer.

If I were a rich man with time on my hands I'd get five of each, shoot the heck out of them and report my findings.

Anyone seen  anything?

Wordmahn - it's hard to blame you for asking this question.  I've been researching this for almost 2 years, and almost everything I have found relates to competition shooting and not for serious defensive shooting purposes.  I ask the same question you do: "Is there a reason for this?"  I have read a lot of conflicting and sometimes diametrically opposing views on this subject, so the only way for me to understand the potential issues is to put a rifle together and go shoot to see what might turn up.  The issue is, I can't test in a systematic way to prove or disprove any of the negative opinions of utilizing a lightweight operating system (including buffer) in an AR15 based rifle.  A few things that ring true to me but I haven't been able to verify...

1) Aluminum carriers are not reliable long term.  A member on ARFCOM has reported that the JP ultra lightweight aluminum carrier has been reliable for him after many rounds down range, but I don't think that this lightweight build (under 4lbs!) is his go to SHTF/SD firearm.  Could it be?  I think he has enough rounds downrange to have some good confidence in it.  I think in this case, low rate of fire (no FA or repeated mag dumps) and good and frequent maintenance practices allow an aluminum carrier to be reliable.

2) In advertising his lightweight recoil system, Tim Ubl, owner of Taccom3G, said that using a titanium or aluminum carrier is not recommended.  I believe that this is just that he doesn't have sufficient experience or data to say confidently that these materials would be ok to use with his polymer recoil buffer system.  He recommends lightweight carriers made from steel.  This is ultimately why I chose to use Faxon's Gunner LW BCG (also cost).  It is a steel carrier with a weight that is within a  tenth of an ounce of most titanium carriers.  I know a lot of ARFCOM folks are shooting both titanium and aluminum carriers with Tim's LW recoil system with no reported adverse issues.  But long term, will there be reliability issues?  Tim has a lot of 3G experience and his usage of lightweight operating systems are devoted to competition.

3) The vast majority of opinions on ARFCOM and other boards say that a lightweight operating system has NO place in a fighting gun.  I have heard a lot of reasons why this is true, and very few reasons why a lightweight operating system is a good idea in a true fighting gun.  The negative reasoning I have heard or read:
 a) The lightweight parts are not as durable and if in a SHTF or extended fight, you may experience failures of these components at the worst possible times.
 b) The LW operating system is tuned using some sort of gas control.  As the gun gets dirty, that tuning becomes invalid.  If you tune the gun with a safety margin, then the extra gas will wreck the optimal flat shooting/recoil of the LW objective
 c) The tuning of the gas system is ammunition dependent.  You lose the ability to use a wide variation of ammunition, and this limits your options.
 d) The AR15 is a light recoiling rifle by design.  You don't need to lighten the recoil in a real fight.  Shaving tenths of seconds off in a competition is the only reason to do any of these lightweight mods.  Buy a really good muzzle brake and you can get a really flat shooter without risking any issues with the complexity and reliability issues in a lightweight operating system
 e) If your rifle is too heavy to carry it all day in the woods, then you need to spend more time in the gym.  (This is going to be true for most of us old, fat guys, even if you can carry your 8-12 lb gun all day)

Honestly, through all my testing and experience, I have not experienced one stoppage in my lightweight SBR.  Not one except when I was tuning the gas and under gassed the rifle deliberately.  But, I clean and thoroughly inspect the SBR after every range trip so it never has seen more than 300 rounds before it was cleaned.    I have confidence that my SBR is reliable enough to use as a SD weapon, but I cannot say that it would be as reliable as a rifle with a "standard" operating system.  Since, like you, I cannot find results from comprehensive testing, I have to rely on my own experience.  I think you will have to do the same.  But, I do not blame you for asking the question!  If you get any additional real data on this subject, please post so that the rest of us can be better enlightened.

Thanks, Linc. We're definitely on the same page.

I'm an engineer so I'm always looking to tweak and improve things. To me, the ability to put far more rounds on target per unit time, seems like a very desirable characteristic to achieve in a fighting gun. But, yes, the traditionalists, and what I call "The Heavy Metal Crowd',  say that you gotta go heavy milspec all the way, or else.  I'm like, Show me the data.

I went ahead and tried it anyway. I even authored a step by step How-to thread on how to build an LMOS gun that's here on page three gathering crickets and yawns. Check it out and tell me what you think. I'd love to hear your input.

The heavy metal guys' model for the ideal fighting gun seems to be something along the lines of an MRAP. MIne is more like a Baja truck -- fast, light, tough, and highly tuned. But, doubts linger, hence, THIS thread. If I were wealthy with lots of discretionary time, I'd do destructive tests, but that's not in the cards for me.

Thanks for your thoughtful post. You definitely get it.

An adjustable gas block will take care of the the overdriven moving parts. It's true that you'll have less energy in the system. Cleaning and lubing schedule would need to be attended to.  A well built system with moderate changes will run fine. If I were going to slog through the sands of Iwo Jima for a couple of months, I'd go milspec. But for a SHTF gun, I don't see a problem. Mine has not failed yet. But I want to run it harder under different conditions to shake it out better and be more confident.