DI 5.56 upper for my old 6.8 lower

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DI 5.56 upper for my old 6.8 lower

Postby jakarta » Thu Sep 07, 2017 8:38 pm

Hi. I am bit of a newb so please bear with me. I bought an old 2008? LWRC 6.8 and it’s my only AR. It’s in great condition (1000 rounds tops). My guns are usually on the exotic side (SCAR, SIG556, etc), but I would like to get a classic DI 5.56 upper so that I can have at least one generic garden variety rifle for SHTF, etc. I want something I can always easily find parts for even years from now so no vendor specific components. Even though I am trying to read and learn about the AR platform, it's a lot of info for a beginner, so I figure I am better off asking some experienced folks here. My questions are:

1. I am assuming that my lower is standard regardless of the year so I should be able to take this 2008 LWRC lower and put a brand new LWRC or any other upper on it (Noveske, Colt, etc). Even though my lower has 6.8 stamped on it, I am hoping that the mag well, etc are the same dimensions and I don’t need to do anything to the lower to run it with 5.56 upper

2. Does LWRC DI follow a basic original design or are the internals proprietary which renders it incompatible with parts from other manufacturers.

3. I do see that it has a “Proprietary DI Bolt Carrier Group", but can it be replaced with a standard one if necessary, or should I simply buy a complete spare BCG and not worry about part interchangeability. if so, what other proprietary parts doe it have that I should I buy spares for

4. I am thinking about 5.56 DI 16.1 STD Rail Upper, but any recommendation for the model and options, are appreciated
I realize this is a LWRC forum, but should I go for some other upper that is “mil-spec” although from what i understand nothing civilian is truly mil-spec?

Thanks in advance
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Re: DI 5.56 upper for my old 6.8 lower

Postby rcrandall » Thu Sep 07, 2017 9:41 pm

The lower is milspec and any milspec upper will fit on it. My recommendation is an upper from BCM (Bravocompanyusa.com). I have a lot of experience with them and they are excellent quality, especially for the price. Take the 6.8 upper off and put the 5.56 upper on, done. Depending on how the 5.56 upper is gassed you might need to put a lighter action spring and buffer in the lower which takes 5 seconds. The BCM guns usually run good with a standard carbine action spring and an H buffer. The H2 buffer and the spring LWRC uses may be too heavy.
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Re: DI 5.56 upper for my old 6.8 lower

Postby jakarta » Fri Sep 08, 2017 6:44 am

rcrandall wrote:Depending on how the 5.56 upper is gassed you might need to put a lighter action spring and buffer in the lower which takes 5 seconds. The BCM guns usually run good with a standard carbine action spring and an H buffer. The H2 buffer and the spring LWRC uses may be too heavy.


Thanks for the recommendation. I wanted to ask how to determined that a lighter action spring and buffer are needed, but after some reading it sounds like people want the heaviest buffer that allows reliable cycling. So I guess if the new buffer works well with H2, just leave it. If there are cycling issues, then go with the lighter buffer and spring?
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Re: DI 5.56 upper for my old 6.8 lower

Postby rcrandall » Fri Sep 08, 2017 9:16 am

Ideally your brass should eject to between 3 and 4 o'clock. If the pattern is at 2 or 1 o'clock then you need more spring and/or mass (heavier buffer). If the brass is ejecting 4:30 or more you are risking a short stroke, not enough gas to overcome the spring and buffer, which means try a lighter spring and buffer. A short stroke malfunction can show in a few different ways.

1. The spent case is ejected but the chamber is empty because the bolt carrier assembly was not pushed far enough back to strip another round off the magazine for feeding.

2. The spent case is ejected but you have a bolt over round stoppage. The bolt carrier did not travel far enough back to engage the rear of the next round in the magazine and instead stopped mid casing on the magazine.

3. The spent case fails to eject. This is tricky because this malfunction could be caused by a weak or broken ejector spring. If the case is still in the chamber it usually means a failure to extract caused by a dirty chamber or an extractor failure. If the gun is way under gassed this malfunction is possible.

Most DI guns are over gassed so a change in spring and buffer may not be necessary, trial and error.
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Re: DI 5.56 upper for my old 6.8 lower

Postby rcrandall » Fri Sep 08, 2017 9:34 am

I just read the post Logan put up, sale price for their DI uppers for $699. That is an impossible price to beat for what you are getting.
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Re: DI 5.56 upper for my old 6.8 lower

Postby LoganBetterton » Fri Sep 08, 2017 9:50 am

jakarta wrote:Hi. I am bit of a newb so please bear with me. I bought an old 2008? LWRC 6.8 and it’s my only AR. It’s in great condition (1000 rounds tops). My guns are usually on the exotic side (SCAR, SIG556, etc), but I would like to get a classic DI 5.56 upper so that I can have at least one generic garden variety rifle for SHTF, etc. I want something I can always easily find parts for even years from now so no vendor specific components. Even though I am trying to read and learn about the AR platform, it's a lot of info for a beginner, so I figure I am better off asking some experienced folks here. My questions are:

1. I am assuming that my lower is standard regardless of the year so I should be able to take this 2008 LWRC lower and put a brand new LWRC or any other upper on it (Noveske, Colt, etc). Even though my lower has 6.8 stamped on it, I am hoping that the mag well, etc are the same dimensions and I don’t need to do anything to the lower to run it with 5.56 upper

2. Does LWRC DI follow a basic original design or are the internals proprietary which renders it incompatible with parts from other manufacturers.

3. I do see that it has a “Proprietary DI Bolt Carrier Group", but can it be replaced with a standard one if necessary, or should I simply buy a complete spare BCG and not worry about part interchangeability. if so, what other proprietary parts doe it have that I should I buy spares for

4. I am thinking about 5.56 DI 16.1 STD Rail Upper, but any recommendation for the model and options, are appreciated
I realize this is a LWRC forum, but should I go for some other upper that is “mil-spec” although from what i understand nothing civilian is truly mil-spec?

Thanks in advance


1. The older 6.8 lowers are essentially the same as any 5.56 lower. These will accept any mil-spec 5.56 upper.

2. Yes and no. The Di uses a basic design with some improvements. Our Di has a proprietary barrel/ barrel nut, along with proprietary rails and monoforged upper reciever. However, you can still change out the bolt carrier and charging handle with any mil-spec components.

3. Our one-piece Di BCG is 100% interchangeable with any AR15/ mil-spec rifle. It's not proprietary so that is likely an error if you see it on our website or anywhere else. This is one of the best components in our Di IMO.

4. Go with the Di upper and you will love it. They are on sale now as well. :wave:
-LWRCi Logan
Email me here: LBetterton@LWRCI.com

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Re: DI 5.56 upper for my old 6.8 lower

Postby van halen » Fri Sep 08, 2017 9:06 pm

rcrandall wrote:I just read the post Logan put up, sale price for their DI uppers for $699. That is an impossible price to beat for what you are getting.


That's what I was thinking, or buy the complete DI rifle and you get the best laid out ambi lower on the market.

YMMV....
I'll just sit here quietly and play with my new rail panels...........
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