Privacy guaranteed - Your email is not shared with anyone.

Welcome to Glock Forum at

Why should YOU join our forums?

  • Reason #1
  • Reason #2
  • Reason #3

Site Description

Last few noob questions before buying (BCM, Colt, DD, build, buy?)

Discussion in 'Black Rifle Forum' started by txpitdog, Jan 4, 2010.

  1. txpitdog


    Aug 18, 2006
    Been searching around on the forum, and the more I learn the more I realize I don't know jack. Two things that appear to be common/popular opinions is that (1) you can't go wrong with BCM, and (2) you can't go wrong with Colt.

    My budget is $1300 max.

    Looking at GunBroker, I can find a Colt 6920 or a 6721 in my budget (found some for $1090). These do not have a rail on the fore-grip, which I would prefer but is not critical. I'd probably be plenty happy with one of these and wouldn't have to worry with "building" one.

    Looking at BCM's website, I can build one on a lower ($350), a standard BCM mid-length upper with carrier and charging handle and OmegaX 9 handguard ($845). I would also need a rear sight ($120+) and mags (3 30rd = $30). This rifle would cost $1350.

    Back to GunBroker, a Daniel Defense M4 is $1250.

    Now for the questions.

    What is the difference between carbine and mid length if the barrel is still 16"?

    Is the BCM really worth another $250 over the Colt, or are they basically the same and I'm just paying for the tactical handguard?

    I've seen some AR15's marked as 5.56 and some specifically marked as .223. I've been told that a 5.56 rifle will fire .223 but not vice versa. Is that reason enough to go with the BCM?

    Are there options with my above BCM build that would help bring the price down but wouldn't give up noticeable quality?

  2. RMTactical

    RMTactical CLM

    Oct 7, 2000
    Behind an AR-15
    It depends. Do you want a rail or not?

    I like to build my own guns so I can get exactly what I want. It is worth it to me.

    The difference in the mid length and the carbine is the length of the gas system and the sight radius. Mid length is suppose to be easier on the gun and more reliable.

    All of the guns were are talking about are 5.56.

  3. furioso2112


    Dec 12, 2007
    Your info on the 5.56/.223 is correct - 5.56 shoots both - the difference, in short, is a different shoulder on the casing and higher power out of 5.56. RMTactical captured the essence of mid-rail succinctly. The gas tube on a mid-length is longer than the gas tube on a carbine; mid-lengths are often paired with heavier buffers which also affects the speed and 'smoothness' of cycling. Quick description if you don't already know: the gas tube directs some of the gasses from the fired round back toward the bolt carrier group, which is driven back against the buffer and its spring, which is contained in the stock of an AR; the reciprocating return pushes the bolt back into battery, cycling the next round. The weight of the spring and buffer affects how quickly and 'smoothly' the operation runs. You probably don't 'need' to know this up front, but since I'm using the terms, thought I'd give a quick and dirty description. Whatever kit you end up buying, you'll most likely get what you need without ever mentioning anything about buffers, springs, tubes, or stocks. Bushmaster's sight has a nice 'see-through/cut-away' of the cycling of an AR, and there are more technical descriptions of the parts and functions on many sites.

    A free-floated rail is not always essential - the DD rails are widely regarded as top quality - I have two (an Omega 7 and a DD Lite 12), both are relatively new to me, but fit and finish are outstanding, and I like the look, feel, and at least the thought that free-floating the barrel (the result of using a free-float rail) results in higher accuracy (when supprting or hanging attachments like a sling on the gun, it hooks to the rail, which, when free-floated, does not touch the barrel) - that said, it might take a while until a shooter's accuracy is good enough to be improved by free-floating. High quality high-rep rails like DD and LaRue easily run $200-$300 or more, depending on length, weight, and attachment.

    Colt's are generally highly regarded; one thing that has affected my purchase of complete Colt is that the some of the pins in the lower of a Colt are a different size than practically all other 5.56 Ar platforms. This can be overcome with offset pins, if you have an application down the road that calls for it (like an aftermarket trigger - many manufacturers make models for both, and there are offset pins you can get for some of the others). One of the main things I like about the AR platform is interchangeability of parts. There are some very nice Colt uppers (including their monolithic rail platform, where the rail runs the length of the handguards and the upper receiver, the idea being that this gives greater stability and acuracy) that you could attach to a 'typical' AR lower from BCM or whomever you like.

    "Buliding" (really, assembling, because it refers to taking a stripped lower and installing a lower parts kit) a lower is a good idea because it gives the builder a better understanding of the gun. It is a simple process, detailed in several YouTube videos (I presume) and some great pictorial and text threads on (among others) I liken assembling a lower do doing a detail strip of a Glock (not the actual physical process, but the mental approach) - it might seem a bit intimidating at first, but take your time, think about what you're doing, get some good instructions, stop and ask if you have questions, and once you do it one time, you'll wonder why anyone would choose not to do it.

    Magpul makes great rear sights for about $55 - there is another recent thread here that showed a retailer selling them for about $45, I think. Especially if you are going to add a red dot later, this should be just fine.

    To keep the price down on a BCM around for a lower (do some research on a couple names to avoid, but there are a lot of great lowers out there - same with the lower parts kit). You could also buy an upper assembly with no handguard or the typical plastic handguards, and add a DD Omega rail later (the DD Omega rails require no gunsmithing and are highly regarded - just put them on, turn down the 'set screws' and you are good to go.

    BCM has several options for their barrels - cold hammer forged, stainless steel, and standard. Barrel twist rate is another thing to consider - IIRC, most if not all BCM are 1 in 7" (favors higher-grain rounds - 62 +), except the stainless steel, which are 1 in 8". 1 in 9" is another common rate, typically 'best' for 55-grain and lower. You certainly CAN fire any 5.56 round weights through each barrel, though - again, to some extent, this is a 'fine tuning' point. BCM recently had sale pricing on many of their complete upper assemblies...not sure if that is still going on.

    Just to give you my perspective, when I first got into 'AR's' I bought a Sig556, then quickly wanted to start changing things - grip, trigger, stock, handguards, etc. - so I bought a bushmaster ORC. The first thing I wanted to do to that was change the front sight to a flip-down, and I realized that the barrel was not finished underneath the gas block...while trying to decide what to do with that, I decided to try to build my own - so I got an inexpensive complete kit and a stripped lower receiver, then started changing a lot of parts on it, and as I shot these platforms and got a better idea of what I wanted and didn't and increased my ability to shoot accurately and quickly and on the move, I wanted a better barrel, a mid-length gas system and heavier buffer, a nicer bolt and free-floated rail, so I bought a BCM stainless upper with a DD Lite 12 rail and put the other parts I liked on it - that is my current 'go-to' setup. I use the parts I didn't like so much on the previous AR's. I am relatively new to the competitive shoting sports, so I suppose I will develop other needs/desires as I continue to shot 3-gun matches, drills, and just for general practice.

    This is kind of part and parcel of the 'Black Rifle Disease' you might have seen reference to. There are lots of ways that people use these rifles, lots of personal preferences, and lots of manufacturers of parts that might seem useless to some, perfect to others. Thus, many people find several ways they like ot use their guns and prefer to have different setuyps based on application. Others like to take a decent stock rifle and see how much they can do with it. You might have some idea now of how you might progress or think about shooting this platform, and that might chnage within a few hundred rounds, or after your first match, or range trip, etc.

    A final piece of advice that I have found reasonable: good barrel, good solid stock, and a good bolt carrier group are essential; the rest of the stuff you might find is a matter of application and preference. Colt, DD, and BCM all fit the bill for these three things.

    There are tradeoffs for most everything else - triggers, mags, rails, controls, slings, grips, optics. It can be intimidating, but you seem to be on a good track - gathering info and interested in trying to make an informed decision to start. There will always be new parts developed, new techniques and new applications to consider. If you start off with a very decent rifle (among your 3 choices, you are practically assured of this), you'll have a rifle that you are very unlikely to think was a 'wrong decision' compared to any of the others. You might end up building or wanting something else quicker than you think now, but any of your 3 options will probably be easy to hold onto and enjoy for a long time.

    I tend to write a lot. Hope it's useful. And don't be tempted to think that I'm any expert. Others might (rightfully) pick apart this post if anyone bothers to wade into it. I spent a lot of time looking, thinking, asking, and thread-reading before and while I was getting into this, and have had (what I consider) success with my buys and builds, but I'm no armorer or high-level shooter or anything like that. I'm just a fan of the platform and using it. The more I learn, the more I see that there is to learn, and the less I feel like I 'know.'
    Last edited: Jan 4, 2010
  4. bambikilr


    Oct 29, 2009
    great post furioso2112...helped me, i've been looking & trying to decide also..ty
  5. Scamp

    Scamp Geaux Tigers!

    May 10, 2009
    That is an excellent post furioso2112, picking up my first AR today, a Colt, and I enjoyed your post tremendously!
  6. Dog,

    I really don't really know what you want as a final AR,
    Carbine, Full Rifle, M4 carbine. You got some good information
    in the previous post so I'm just chiming in.
    I have a Colt 20'' bbl. rifle and a BCM mid length.
    Both are great.
    Colt does not offer a mid, just carbine and rifle, so I went BCM and
    glad of it.
    Check They have several Colt's that you
    could build on. Cheapest is $982. Several other models just over
    $1000. and that's delivered price.
    Keep searching and learning and you will build or buy a fine rifle. Luck.


    Sep 29, 2005
    furioso2112 really hit the nail on the head and covered everything you need to know. The only thing I'll add is that all newly manufactured Colt's have mil spec (.154) trigger pins. If you get an older Colt it will have the larger .170 trigger pins.
  8. surety agent 1

    surety agent 1 PaleHorseComing

    BCM 16" Mid-Length Complete Rifle at G&R Tactical for 1135.00 that one gets my vote.
  9. furioso2112


    Dec 12, 2007
    Now that you mention, that seems to ring a bell. I'll make a note of it...and might have to go buy a Colt to see what all the fuss is about. I already have a 'vintage' Colt magazine to put in it - something a friend found while cleaning out a relative's attic, gave it to me. I think it is a 5 or 10-rounder...never really looked at it that closely.