LMT Enhanced BCG as a Spare? And the Benefits of a Carbine Gas AR

[w3453l]

Hello everyone,

I'm planning to start buying some BCG's while it's still a good time; although I'm going to be putting these away for farther down the road as either spares or for building up more stripped lowers.

I was eyeing the LMT Enhanced BCG among others, and the description says its recommended for carbine gas systems with barrels of 14.5" or 16".

Now the plan was to have it as a spare for a Defender 2000 upper receiver, although in the future I may have it rebarrelled with a mid length gas system. So my question is: would I have any issues running the enhanced carrier? Would it just be a safer bet to go with the standard carrier instead?

I tried reading through older threads on the topic of the LMT Enhanced BCG, and I found that there have been revisions to it through the years, although I was not able to see what year each revision was made. So I apologize if I mention something that has already been addressed in the more recent version of the BCG.

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This lead me to thinking:

Is there any advantage to a carbine gas length 14.5" or 16" rifle vs a mid length gas system in the same barrel length? Provided that the rifle is of a reputable manufacture with a proper sized gas port. It seems that the trend among AR manufactures now is moving towards producing mid length gas systems in barrels of 14.5" and 16" lengths.

I have seen the statement repeated "a properly gassed carbine AR will run as well as a mid length gas AR". The key words being "as well as". But is there any benefits at all that a carbine gas length AR has over a mid length?

Or do manufactures stick to the longer carbine AR's simply due to military contracts/specs and the budgeting that goes with them.

Mods: if this should be split into two threads please let me know.

Thank you in advance for any contributions to the thread.

[zackmars]

there is no benefit to a 16" carbine, none whatsoever.

you will have no trouble running an enhanced carrier

[firefighter37]

I have found that the enhanced carrier will work wherever a std mil spec carrier will work when paired with a mil spec bolt. This includes 16" middy, carbine, 11.5", 10.5", 8.5" 300 blk.

Carbine vs midlength, at the end of the day, they both work. The mid may be easier on parts but they both work just fine.

[ABNAK]

I have a complete Enhanced BCG in a BCM 14.5" middy and it works fine.

[Rifleman_04]

there is no benefit to a 16" carbine, none whatsoever.

Yeah, no benefit except for the boring reliability.

I wouldn't worry about the carbine vs. middy gas thing. If you already have the carbine run it and the enhanced will work fine.

[Rifleman_04]

I have seen the statement repeated "a properly gassed carbine AR will run as well as a mid length gas AR". The key words being "as well as". But is there any benefits at all that a carbine gas length AR has over a mid length?

I think you got that backwards. A properly gassed and buffered middy will run as well as a carbine. The differences between the two are still pretty insignificant unless you are talking about an intermediate like a Knights.

[zackmars]

Yeah, no benefit except for the boring reliability.

I wouldn't worry about the carbine vs. middy gas thing. If you already have the carbine run it and the enhanced will work fine.


middys are also boringly reliable.

so, a carbine still offers nothing

[Rifleman_04]

middys are also boringly reliable.

so, a carbine still offers nothing

Without turning this into a battle of the gas systems but not quite and obviously depends on the setup. I've seen them choke in the winter and turn into single shots while 16" carbines keeps chugging along. The carbine is standard and has known reliability.

[zackmars]

there is no standard for a 16" carbine.

there is no TDP

as long as both have the proper gas ports, and use good quality parts, both will be extremely reliable

[Rifleman_04]

there is no standard for a 16" carbine.

there is no TDP

as long as both have the proper gas ports, and use good quality parts, both will be extremely reliable

Diemaco C8 SFW doesn't follow the TDP but was adopted by certain units to use in the arctic where the cold was a main factor for reliability concerns.

Edit: No TDP for middy either and frankly nobody cares about the TDP if you buy from a known quality manufacturer.

[zackmars]

Diemaco C8 SFW doesn't follow the TDP but was adopted by certain units to use in the arctic where the cold was a main factor for reliability concerns.

Edit: No TDP for middy either and frankly nobody cares about the TDP if you buy from a known quality manufacturer.

the c8sfw is a relic.

do you have any actual data proving that a 16" carbine is more reliable than a 16" middy?

[Rifleman_04]

the c8sfw is a relic.

do you have any actual data proving that a 16" carbine is more reliable than a 16" middy?

Just what I've seen. Doesn't matter though as both work. Point I'm making is if the guy already has the carbine it's not worth it to change out for a middy because of something read on the internet.

[zackmars]

Just what I've seen. Doesn't matter though as both work. Point I'm making is if the guy already has the carbine it's not worth it to change out for a middy because of something read on the internet.

cant argue that

[JG007]

I was told by lmt they don't recommend using the enhanced carrier in a carbine (buffer iirc

[Rifleman_04]

I was told by lmt they don't recommend using the enhanced carrier in a carbine (buffer iirc

Weird because I'm pretty sure one of its designed intended uses is to vent the extra gas from a carbine.

[MegademiC]

No benefit to carbine gas over a mid for a 16"bbl.

If you already have a quality carbine (lmt counts here) I would keep it.

Can't comment on the bolt/carrier.

[Iraqgunz]

I use the LMT E-Carrier in my 11.5", 12.5 SBR's and my 20" rifle. I see no real benefit in a standard carbine.

[556Cliff]

Weird because I'm pretty sure one of its designed intended uses is to vent the extra gas from a carbine.

LMT has said that the Enhanced carrier was designed for use in 14.5" barrels with the carbine gas system that have worn/enlarged gas ports, by chance making it perfect for 16" barrels with the carbine gas system due to their increased dwell time.

I have also been told by LMT not to use the Enhanced carrier in 20" barrels because it would change the timing too much.

[JG007]

Where are the claims from about it being good for a carbine? I called and spoke to gene when I first tried to fit my BCM bolt into the LMT enhanced carrier and it was extremely tight, the police range staff didn't think it would function, he said it was meant for a longer buffer rifle system and I mentioned I was using it within longer a 5 buffer

[w3453l]

cant argue that

Thank you to everyone.

I'm certainly not going to scrap a good current carbine upper with plenty of life left in it. It's just that I'm currently looking to buy some spare parts for future use. I was just curious for in the event that I hopefully shoot out the barrel on the current upper. In that case I'd be able to change the gas system to mid length along with the barrel itself.

My wondering about the industry moving towards mid length was out of curiosity. Truth is that I really haven't heard any negatives about the mid length gas system. My statement about hearing multiple times that "carbine gas rifles run as well as mid length rifles" was correct. I read a lot of good things about it, and it's at a point where it seems like it's more preferred over carbine gas by default these days. As an example, there was a thread a while back about whether or not members would still recommend a Colt 6920/6720 as a starter AR. A few points brought up in that thread said why the Colt if similar options exist with mid length gas being the big plus. I know it's "internet talk", but that's why I come to ask here since this looks to be one of the last sites with unbiased/true user opinions.

As for the enhanced BCG from LMT, I was a little confused because from what I read on LMT's website they stated its for carbine gas rifles with 14.5" and 16" barrels. At the same time I have read from numerous people with different setups (Iraqgunz above for example) that they have the LMT Enhanced BCG, and have absolutely no issues with it.

[556Cliff]

I just got this in an email from LMT.

Question: "Is the Enhanced carrier still only recommended for use in 14.5" and 16" barrels with carbine gas systems? Has anything about the Enhanced carrier's design been changed to make it usable with other barrel lengths with different gas systems?"

Answer: "The enhanced carrier will work on all the 5.56 direct gas barrel lengths we sell."

[JG007]

Interesting, I just checked and the only specification listed was that it was


*For usage with full-automatic rifles.

http://www.lmtstore.com/parts/bolts-carriers-and-groups-complete/556-enhanced-fa-bolt-carrier-group.html

plus the conversation I had on the phone

good to know

* I was also surprised that it looks like none of the complete guns ship with it, and they (almost?) all come with the regular semi auto bcg

[556Cliff]

Something must have changed but there is no difference in vent hole size or location on any of my 4 LMT Enhanced carriers purchased between 2011/2015.

[tom12.7]

Out of the box, a LMT enhanced carrier has always been more durable for the bolt. It may not have been more reliable in operation. Using that carrier in an unkown combination of uppers can reduce reliability in systems that have a higher carrier speed. In the balance of porting and reciprocating mass, a more reliable system keeps the carrier speeds in check. The basically small delay in timing can make a large difference in function. A delay in time allows a reduced amount of work, that can increase speeds and hurt reliability. As long as the carrier does not overspeed, it does tend to be more reliable.
It is very possible to make a carbine action/carbine gas combo that works well with the LMT carrier with less bolt stress/strain issues. It is also very possible to use the LMT enhanced carrier with longer gas systems and rifle like action systems for a further reduction in issues.