5.56 LMT Enhanced Bolt vs. Mil Spec Phosphate: Service Life and Functioning?

[AR-Tenner]

Hi Folks,

I am very close to picking up an LMT enhanced bolt (bolt only) for my 20" AR in 5.56 (rifle gas, rifle buffer assembly), and wanted to get a straight answer as to the expected service life. I also have heard conflicting reports of whether the bolt by itself, when run in a standard mil-spec carrier, causes the rifle to function differently. Some folks online have said that the bolt also slows down the system and bleeds off more gas than the standard, whereas I was under the impression that that was just the carrier. I have also heard it is hard on cam pins, but I wonder whether that is actually the carrier, not the bolt, or whether it might be BS.

Does anyone know from a technical perspective, or from personal experience, whether the enhanced bolt will keep the same functioning (dwell time, extraction, ejection) as a standard mil-spec bolt when used in a mil-spec carrier? I don't want the bolt to function differently, especially in my 20" rifle, or the 16" midlength with a rifle buffer system, so if it slows down the system, that is not something I want.

Finally, does anyone know what the technically-forecasted lifespan of the LMT enhanced bolt is in 5.56? Better yet, does anyone have one with a high round count through it, or better still, broke one through normal use?

[NWshooter]

Im no expert but I believe the cam track was altered to incease the dwell time making in incompatible with rifle length gas systems. Hopefully someone with more knowledge than I can give a better answer

[Cold/Bore]

Hi Folks,

I am very close to picking up an LMT enhanced bolt (bolt only) for my 20" AR in 5.56 (rifle gas, rifle buffer assembly), and wanted to get a straight answer as to the expected service life. I also have heard conflicting reports of whether the bolt by itself, when run in a standard mil-spec carrier, causes the rifle to function differently. Some folks online have said that the bolt also slows down the system and bleeds off more gas than the standard, whereas I was under the impression that that was just the carrier. I have also heard it is hard on cam pins, but I wonder whether that is actually the carrier, not the bolt, or whether it might be BS.

Does anyone know from a technical perspective, or from personal experience, whether the enhanced bolt will keep the same functioning (dwell time, extraction, ejection) as a standard mil-spec bolt when used in a mil-spec carrier? I don't want the bolt to function differently, especially in my 20" rifle, or the 16" midlength with a rifle buffer system, so if it slows down the system, that is not something I want.

Finally, does anyone know what the technically-forecasted lifespan of the LMT enhanced bolt is in 5.56? Better yet, does anyone have one with a high round count through it, or better still, broke one through normal use?

The LMT enhanced BCG has a modified cam track that does not slow anything down, but rather delays the unlocking of the bolt a couple of micro seconds to allow for chamber pressure to decrease. This eases extraction and increases bolt life, which is a good thing. It is the carrier that does this, not the bolt. You can run a standard bolt in the enhanced carrier to the same effect.

As far as if this will work in a 20” rifle, that I don’t know. I don’t have any experience with the LMT enhanced BCG but they seem to be popular with folks running 11.5 suppressed uppers. I believe that the enhanced carrier was designed for the M-4 carbine with a 14.5” barrel and carbine length gas system. You don’t hear too many people running them in 16” midlength systems, let alone a 20” rifle gas system since those two systems already increase the time it takes for the bolt to unlock. The longer the gas system, the longer the unlocking time, which results in lower chamber pressure while unlocking which is ideal for a number of reasons.

I think most more experienced M4C members here will tell you to save your money and go with a standard MilSpec BCG with a 20” rifle system since the original Stoner gas system was designed around a rifle length system and anything shorter than that is a modification that has its own particular compromises and shortcomings, hence a need for an enhanced BCG.

But I would also be curious in how the enhanced carrier would function in mid length and rifle length gas systems as a means to increase durability and longevity of the platform. How much do you plan on shooting? You can probably count on a standard mil spec BCG in a 20” rifle to last at least 10,000 rounds. The price of the ammo will far outweigh the money saved on fewer broken bolts.

[Iraqgunz]

Sounds like someone needs to understand their terminology better. The bolt has little to do with it. It's the carrier that has a modified cam pin path, the intake port, exhaust ports, etc..

If you use the search feature you will find several in depth threads on the LMT E-Carrier.


Hi Folks,

I am very close to picking up an LMT enhanced bolt (bolt only) for my 20" AR in 5.56 (rifle gas, rifle buffer assembly), and wanted to get a straight answer as to the expected service life. I also have heard conflicting reports of whether the bolt by itself, when run in a standard mil-spec carrier, causes the rifle to function differently. Some folks online have said that the bolt also slows down the system and bleeds off more gas than the standard, whereas I was under the impression that that was just the carrier. I have also heard it is hard on cam pins, but I wonder whether that is actually the carrier, not the bolt, or whether it might be BS.

Does anyone know from a technical perspective, or from personal experience, whether the enhanced bolt will keep the same functioning (dwell time, extraction, ejection) as a standard mil-spec bolt when used in a mil-spec carrier? I don't want the bolt to function differently, especially in my 20" rifle, or the 16" midlength with a rifle buffer system, so if it slows down the system, that is not something I want.

Finally, does anyone know what the technically-forecasted lifespan of the LMT enhanced bolt is in 5.56? Better yet, does anyone have one with a high round count through it, or better still, broke one through normal use?