My DDM4 V5 Middy vs New BCM Middy Challenge (Thanks Grant!)

I just picked up a new BCM middy pieced together from a complete upper and lower, both from Grant. The upper consists of a 16” BCM lightweight BFH mid-length barrel with FSP, DD Omega 9.0 rail, and BattleComp 1.0 and standard BCM lower with Tango Down pistol grip. I added a BCM BCG, Gunfighter Mod 4 CH, Tango Down stubby VFG, DD A1.5 rear sight, and Magpul MOE stock to round out the package. I ordered it on Black Friday and had the upper and lower in hand in a little over a week.

Grant was great with answering all of my numerous questions along the way and was awesome in putting my order together. Quick turnaround, even with my particular component requests and fast shipping, which probably cost way more than the shipping charge. Great service and my only complaint is the probable impact on my savings account. :smile:

The primary purpose of this BCM is to answer a lot of my X vs Y features and manufacturer questions. My first AR is a DDM4 V5 with EoTech 512 absolute co-witnessed with Troy BUIS, and Troy rail covers. For my second AR, I wanted to try a BCM, LMT or Noveske, a FSP and fixed rear sight with lower 1/3 co-witness with an Aimpoint RDS, a compensator/brake, and a light-weight barrel. I plan on running it with the iron sights until cash frees up for either a T-1 or other Aimpoint RDS. After I get the RDS, I’m planning on putting these two up against each other in my own Daniel Defense vs. BCM challenge. Definitely not an apples to apples comparison, but I wanted to compare the features that I typically would get feedback like “it basically comes down to personal preference, but you can’t go wrong either way”. I want to try the different features head-to-head and hope to take both to a carbine class sometime next year and figure out what features I like best. I’m still pretty new to AR’s, so this is a very much a learning process for me.

I took both to the range today¸ where I had planned on sighting in the BCM and seeing how it ran with both XM193 and XM855, test it with different magazines, and test out the BattleComp. It ran flawlessly, even with the cheap 10 round metal ProMags that I need to use with the Lead Sled. I had a few malfunctions (FTF) when running the ProMags with my DDM4. Only ran through about 140 rounds, but I’m liking everything about it so far.

I didn’t intend on starting the “Daniel Defense vs BCM Challenge” today since I brought the DDM4 just to run some steel cased ammo through it and see how it did (first time running steel cased ammo through any AR). However, I couldn’t help but start comparing the two. Not an apples to apples comparison, since they both have (or eventually will have) much different components, but just initial/overall impressions. The BCM seemed to run much dirtier than the DDM4. I only went through 140 rounds today and there seemed to be noticably more carbon build-up and in more/different locations than I had noticed on the DDM4. For example, when I pulled the bolt, the curved portion of the bolt behind the gas rings was dry and caked with carbon. I know I lubed that area before shooting. I also noticed a lot of carbon on the buffer and in the buffer tube. I have not noticed that much carbon in the DDM4, particularly on the buffer and in the buffer tube. Neither affected function (I think the Filthy 14 was MUCH worse) and I’ll take it as a warning to be more aware of lube in future use.

I also noticed a difference in the ejection pattern between the two. The DDM4 ejection pattern with XM193 and XM855 was consistently to the 4-5 o’clock position whereas the BCM would consistently eject (with the same ammo) to around 2 o’clock position with dents on the side of the brass in about the same spot. Not sure if the difference in the ejection pattern and seemingly “dirtier” operation of the BCM are related. The BCM functioned just fine, so I assume it’s not a big deal.

I thought my DDM4 was pretty light compared to my friend’s Colt 6920, but the BCM is MUCH lighter than my DDM4. Yeah the DDM4 wears an EoTech and Troy rail covers and the BCM has a light-weight barrel, but still. I’m leaning toward the lighter weight and thinking of replacing the Troy rail covers on my DDM4 with the basic ladder covers. One minor thing that I noticed is that the anodized finish of the DDM4 appears more glossy/smooth and the BCM appears more flat/porous. The finish of the DDM4 seems to keep oil on its surface and the finish of the BCM seems to soak it in. Nothing that would affect function, at least I don’t see how it would, but just something I noticed.

One side note on the DDM4 and steel cased ammo. I ran 40 each of TulaAmmo 55 gr and 62 gr .223 Rem. On the 55 gr, the bolt failed to lock back after the last round half on half of the 5 round strings. The 62 locked back after the last round on all of the 5 round strings, but I got a failure to extract on the second round on one of the strings. I’ve read where the steel cased ammo tends to start jamming due to build-up of carbon around the casing in the chamber since the steel casing doesn’t expand like the brass casing. Not sure if that contributed to the failure to extract, but I assumed so since a likely cause would be the sticking of the spent casing in the chamber. The spent casing was about a third of the way out and I had a tough time pulling the magazine. I don’t think I will end up running steel cased ammo much, but I wanted to see how it performed. Is there any way to improve how steel cased ammo runs in an AR? At this point I think I’ll likely stick with brass cased ammo, but just curious.

Overall, I think it’s going to be very tough for me to decide a “winner” for this challenge. I think it’s going to end up a preference for one of them for a particular application (say carbine training) and the other for another particular application (say USPSA rifle matches). It’s just that I have to try them both to satisfy my curiosity. I’m still curious as to carbine vs middy, trying Colt/LMT/Noveske, and a LMT SOPMOD/B5 stock, so there’s likely another future competitor, or two, for this challenge. :laugh:

The competitors.

Dents/marks on brass from ejection from the BCM

Well if you do put an LMT in the mix, if it is like mine, it is boringly reliable. Mine does not have a high round count, 1500 or so, but has never hiccupped once.

Even ran some Wolf steel cased ammo at a relatives house one afternoon and it ran through that just fine.

Really looking at getting a BCM for my son.

Is that DD rear sight on backwards ?

It is.

I had a few malfunctions (FTF) when running the ProMags with my DDM4

Render them safe with a hammer. You’ll thank me later.

Dents in the brass is a sign of strong ejection of the empty case… not a problem in my book.

I doubt you’ll have issues with either one. It will likely come down to which one feels better to you.

I can’t really tell from the pics, but it looks like that DD has an A2 birdcage. That will be hard to compare with the Battlecomp. If you care about comparing the feel I would use the same flash/comp on both.

I have both examples in your challenge. A DDM4V3 and a BCM 16 LW midlength (on an RRA lower). Both are great rifles and function very well. My DDM4V3 did NOT like Tula. I had many many extraction problems, some which required me to use the mortar method and even more which required a cleaning rod inserted from the muzzle to tap out the case. Very disappointing and as a result I will never use Tula in any AR again. I have fired Wolf through both and am happy to say that there were no problems what so ever. Thanks for the report.

If by deciding a “winner” you mean simply liking one of your rifles better than the other, then great.

But if you mean trying to quantify and qualify an assertion that one company is “better” than the other I would caution you against that.

In the end, your preference is likely to come down to the configuration of the rifles; mainly FSB vs longer rail and A2 vs BC.

Also remember what they say about “samples of one.”

I’m not knocking your post or your intent, but again, I would caution you against in the future going around saying “X is better than Z” based off of your limited experience with a sample of one.

With your ejection pattern in mind; it sounds like the BCM is over gassed. Brass should be ejecting 3 o’clock to 5 o’clock. Your bolt and other things being dirtier support this. Might be something to play with if it bugs you.

Nonsense…

Read this thread before continuing to spread that nonsense about ejection pattern around…

https://www.m4carbine.net/showthread.php?t=89083

My experience with DD barrels has been they run their gas ports on the smaller side.
Out of the 3 I used for builds, 2 would short stroke, (among other things), with lower pressure ammo.
Keep in mind that the mid-length gas system does not have a uniform spec for gas port size.

I can tell you that one of my BCM mid-length uppers has a gas port of .062".
The 2 DD barrels I’ve worked on that short stroked, the gas ports were in the high .05"s.
Measuring was done with a standard digital calipers.
I fully realize that there are better ways of measuring gas ports.

As far as ejection patterns…
I don’t care where it ejects really, I just want to see it eject consistently.

My own experience… YMMV.

Overreact much? I said, “Might be something to play with if it bugs you.”

Settle down.

Direction of ejection is a non-issue.

Yeah, pretty much that.

Quick response since I have to run. Just thought that I should clarify since I can see how the intentions of my post could be misinterpreted. I see your point and I want to clarify that my intentions are NOT what you are cautioning against.

My primary intent for this challenge is to compare different set-ups, features and components head-to-head against each other and find out what works best for ME or what features I prefer. I figured having them on two ARs so I can shoot them side-by-side would help me more than trying the same AR and swapping out components. I also wanted to try other AR manufacturers/brands, so figured that this was a good opportunity to try out a different brand as I’ve been wanting to try a BCM, LMT, Noveske, Colt, etc.

My intention is not to establish that one brand, component or feature is “better” than the other in a global sense. Again, just to find out what I prefer. Sure, if someone asks for my opinion on one vs the other, I’ll share my opinion based on my experience , which understandibly is a very limited one in both length of time and breadth of experience handling quanity and variety (my two samples of one).

In these types of things, my typical response would be to share what I prefer and what works best for ME and encourage the person to try both out and see for themselves. Just thought I would share my journey through that process. If you are are at the range with me, you can try my rifles to see. If someone is going through the same search as me, maybe some of this will help.

Thanks to everyone for the feedback so far.

And yes, the DD A1.5 is backwards. The box didn’t include instructions and the pic on the box had it oriented that way, but not mounted on a rail. I thought it was pretty obvious. I should’ve known better as I’ve been on Daniel Defense’s website A LOT lately.

For who exactly? For you? For me? Certainly not for everyone.

I collect my brass when I’m done shooting. Sometimes weather or drive time does not permit me to use an outside range. When I do have to go indoors, if brass ejects forward of the firing line, it’s gone. It just happened to me recently with a new gun. I wasn’t mad, but I’d like to get it squared away (even if not soon) so I can collect my brass.

Like I said if it bugs him, he can address it. For anyone arguing it’s nonsense, leave it alone. You don’t have control over all aspects of shooting or when and how a gun will be used.

Sorry for mucking up your thread, drck1000.

Good luck with your experiment and your rifles.

that’s not what you said. you claimed that it was an indicator that the gun was overgassed. this is simply not true…

If collecting brass at an indoor range is important, you can buy different buffer weights to achieve your desired result.

It takes 1 minute to change out the buffer.

Or this.
http://www.cheaperthandirt.com/ARR033-7.html

That’s just asking for a malfunction.