Since the initial posting of this article in October of 2008, the BCM
carbine has undergone several changes. Scroll down to the 081001
heading below to find the original specs and rationale for this rifle.
There have been five main transformations and they are listed in the
order that they came about.
As mentioned at the end of the original article, the light wasn't
"mission critical" for this gun, but I found a way to do it relatively
economically. The biggest cost savings were realized because I already
had the light in the form of a Surefire X300. One of the benefits to
this light is that it is easily swapped between multiple firearms to
include both pistols and rifles. Therefore, once you have the light,
the only added cost is the mounting system. I used the Streamlight
AR-15/M16 Tactical Illuminator Mount that I purchased through
Brownells. The mount attaches by drilling a pair of holes through the
handguards, and it has relief cuts in the back of the mount to
accommodate the ribs of the plastic handguards.
One concern
with this mount is that it follows the taper of the handguards and is
therefore not mounting the light parallel to the bore. I found that I
could mitigate this by at least installing the mount parallel to the
seam in the handguards and did so by setting the handguard flat on a
bench and using wood blocking to support the rail to ensure that it was
parallel to the bench. This means that the light is still not parallel
in the horizontal dimension but I have found no ill effects from this
at the distances where an X300 is useful. It may become an issue out
past 100 yards but then the X300 isn't the best solution for that
application anyway.
Care should also be taken when installing to
avoid causing clashes with the FSB. The X300 installs by sliding onto
a rail, and the Streamlight rail is designed to accept the light by
sliding it on from the front. If you mount the rail too high on the
handguards you can wind up unable to slide the light on because the FSB
is in the way. Mock up your installation with rubber cement, rubber
bands, etc prior to committing to a rail location. Measure twice, cut
once! I learned this the hard way and now have an extra set of holes
in my handguard. I was only off by 1/8" +/- so the rail still covers
up the old holes, but it is not ideal.
As reported elsewhere on this site I have been reviewing a couple of
slings from Boonie Packer, and their basic two-point is one of them.
The previous sling on this gun was the excellent Blue Force Gear
Victory two-point
which retails for $36, which is turn based on the Blue Force Gear
Vickers Combat Applications Sling (or BFG VCAS) that retails for $60. As Vickers himself mentions on his
website, his
design influence for the quick-adjust two-point sling came from a
Boonie Packer product to begin with. I have found the $16 (shipped, by
the way) Boonie Packer to be an excellent budget alternative to the
more expensive BFG products. You do give up a little bit in terms of
quality of materials, but so far this has not proven to affect function
for me at all. $16 is certainly more in line with the rationale for
this carbine than $60. Do make sure that you order the 1=1/4" version
as the wider versions require different attachment methods. The 1-1/4"
is the way to go for this reason.
Larue PoBoy Magnifier Special $200 ($200)
It would appear that Larue may be currently out of stock on these,
which would be a shame. Essentially they take some sort of surplus
2.5x magnifying sighting device, modify it to remove the reticule, and
pair it with their QD Pivot Mount LT649-30
which
retails alone for $150. That same mount, with the Aimpoint 3x
magnifier, is $620 in a package deal.
At $620 it
does not fit with the rationale for this carbine, but at $200 a
magnifier offers options, and with the QD nature of the Larue levers it
can be moved to other carbines to spread the cost and utility.
I
have used the magnifier on the gun in one match to date (See "April
2009 SFDCC AAR" ). This
match required shots out to 120+ yards on Stage 3 as well as some 50
yard shots on Stage 1. While neither of these distances would require
a magnifier I thought they would be a good chance to work with the
tip-off mechanism of the mount. As noted in the AAR, I found it to be
an easy manipulation that could be done on the move when going from
distance to close range targets. I have also since discovered that, if
shooting with both eyes open, the magnifier can be left in place and
the whole system used similar to an ACOG. I think that I would tend to
probably use the magnifier tipped off and out of the way and deploy it
to vertical only when needed.
Having the Troy flip-up rear
BUIS works very well with the magnifier. While something like a Magpul
MBUS rear would be more in line with the "budget" motivator for this
carbine, it would not work as well as a primary sighting device as the
Troy for dedicated iron sight during extreme light-weight use (no
optic) requirements. On the plus side for the Magpul product it would
appear that if it was already deployed in the vertical, and the user
went to tip the magnifier up it would simply push the MBUS down out of
the way. The Troy would require that you first press the locking
button and fold it out of the way.
Bravo
Company has finally released their own lowers, and is selling them
through retailers like G&R Tactical, which is where I ordered
mine. These lowers come with a standard M4 stock on milspec tube with
"H" buffer, A2 grip, and Magpul MOE trigger guard.
I chose to take the MOE pistol grip off of the original lower for this
gun and install it on the BCM simply because I find the finger groove
on the A2 to be intolerable over long strings of fire. For now I am
leaving the M4 stock as I see no real downsides to it, and I am leaving
the H-buffer although that may cause reliability issues with my chosen
ammunition (Wolf) and the longer midlength gas system. If it does I'll
go back to the carbine buffer from the original lower. I am also NOT
bringing over the modified Bill Springfield trigger. While I like that
trigger I actually think it may be counter-productive in terms of
teaching new shooters and think that the GI trigger is better left
unmodified.
"H" buffer comes standard in BCM lower
Hammer, un-notched
Other guts of the lower
On initial inspection I have two "gripes" with the
lower. The first is that I really wish there had been an option to
have it come with the MOE grip and stock. It already comes with the
MOE trigger guard and it would be nice to round out the set. A BCM M4
stock body retails for $45 and BCM sells the MOE stock for $57 for a $12 premium. A MOE pistol grip is a $20 part and a Cavarms A2 grip is a $6
part for a $14 premium. That means that total RETAIL premium is $26,
and it strikes me that if the swap was made at cost it could translate
into a $15 premium on the lower at most. I would have gladly paid
$365-$370 for an all-MOE lower. An argument could be made for selling
the lower without grip or stock, but then you're only going to get the
credit at the lower dealer price and wouldn't be as attractive.
The
second gripe is more of a gripe with Magpul than BCM. Their MOE
trigger guard is a great idea in that it offers a lower cost option to
their Enhanced Trigger Guard at $20. The problem is that the MOE isn't the exact same contour as
the Enhanced and actually doesn't fill the gap as well. In fact, the
part of the gap left still exposed is the most offending part which is
where the "ears" of the meet the grip itself. I really wish that
Magpul would just mold in a "gapper" to their MOE grip and charge an
extra $2 for the thing and be done. I love the grip, but having to add
additional parts is somewhat frustrating.
MOE trigger guard, and the gap that is left even when installed
I have to admit, adding this bolt carrier group was a bit of a vanity
thing. I just like the idea of an all BCM carbine, and when I got the
notification email that the BCGs were in stock I went ahead and jumped
on it. The good news is that these are some of the best BCGs you can
find on the market, and with LMT reportedly shipping with MIM carrier
keys the BCM becomes even more attractive. The original LMT will go in
the tool bag, well lubed and wrapped in a Ziplock bag, as a spare for
me and as a diagnostic tool for working with other people's
non-functioning guns. As an added plus on the vanity side BCM is not
etching their logo onto the carrier which can be seen from the ejection
port. No functional benefit, but certainly "cool". The
unfortunate side is that BCM BCGs are now up to $160 over the $130 I
paid for the LMT last year. If this is their solution to a material
availability problem which led LMT to go to MIM on the carriers, I'll
take the added $30 price over the MIM solution all day long.
BCM bolt/carrier group with similarly marked upper and lower
Summary to Date
I haven't had a chance to shoot the carbine yet with the new lower and
BCG, however given BCM's track record I expect no issues other than it
possibly being over-buffered for the midlength gas system and weak Wolf
ammo, and that is easily rectified at the range. I have been really
happy with the new sling, light and mount, and magnifier. I think the
magnifier is a bit of a niche item, and with it possibly being
unavailable going forward I don't think that the $600+ price tag for
the equivalent Aimpoint product fits with the rationale for this
particular gun. I may revisit that option on another carbine where
costs are already higher and the end use is different.
So where does all this swapping around leave us in terms of total price for the "budget" build? Let's do the math
$485 BCM barreled upper $350 BCM complete lower $160 BCM BCG $25 Cavarms mid-length handguards $24 BCM charging handle $140 Troy folding rear sight $26 Boonie Packer two-point sling. $1,200 TOTAL functional carbine ($1,110 if the Magpul MBUS is used in place of the Troy)
$250 Surefire X300 $20 Streamlight mounting rail $270 TOTAL add for weapon light
$465 add for Aimpoint C3 in ADM mount
$200 add for the Larue PoBoy magnifier/mount combo
$2,135 TOTAL COMPLETE for the carbine as it currently typically sits in my safe
8 lbs 6.4 oz
$1,935 TOTAL for the carbine as I typically run it without magnifier (my suggested configuration)
7 lbs 9.3 oz
$1,665 TOTAL for optic without light or magnifier
7 lbs 7.6 oz
$1,470 TOTAL for light without optic or magnifier
$1,400 TOTAL for optic & magnifier without light
8 lbs 2.0 oz
Current Conclusions
Proof of concept to date is great. So great, in fact, that this is the carbine that I have been using for the majority of my shooting events. It offers everything I need, in an easily reconfigured package that I can tailor to my needs at the time without being unnecessarily heavy or unwieldy. I've seen a lot of chatter online about people "needing" heavy, expensive stocks on mid-length gas system guns, but I just don't see it. If I wind up feeling like there are balance issues with the gun I'll have the barrel in front of the front sight turned down to a thinner profile for $65 instead of buying a $200+ stock. While I have nothing against quality gear, this rifle has become about "making due" with lower end and less expensive (but still top quality) options, and putting a $200+ stock on it just to balance out a $350 rail system that I don't attach anything to seems kind of counter-concept. What I am finding is that it just seems counter-productive. What I thought would be "making do" is in fact excelling at all uses and has me questioning the rationale for heavier and more expensive guns in the safe.
Basic AR-15 Carbine Build
After writing "I Can Build a Better AR for Less", and with the release of the latest batch of upper receivers from Bravo Company USA, I decided to put my money where my mouth is, and build a basic AR carbine. the mission for this carbine, since "mission drives the gear train", is to have a basic, high-quality, so called "general purpose" carbine that can be built as inexpensively as possible and be used for matches, training classes, and to be loaned out for others to use for the same.
As a potential loaner rifle for a new shooter there are certain things I think are key. 1) It has to be simple. "Simple" does not necessarily mean "KISS" or "retro". Simple means that it should be as un-intimidating as possible to a new shooter but to still provide them the tools they need to get good hits and learn. 2) It has to function. A new shooter is not likely to be able to asses and correct various potential malfunctions with a loaner gun. If the carrier key or castle nut come loose they may not have the knowledge, skills, or tools to make the needed corrections in the middle of a class. As such it needs to be built correctly from the correct materials to be as reliable as possible. 3) It has to make learning easy. On the one hand, many people argue that everyone should learn iron sights first. I happen to disagree. Using a red dot sight (RDS) greatly increases the shooter's chances of getting good, fast hits. Period. Why do we expect new shooters to take the longer, harder road to learn to shoot the iron sights? Give them the tools they need to get good hits. if they decide to pursue defensive shooting seriously they can always learn the irons sights later. 4) It has to be modular. Some classes may have a night shoot, some may not. Some students may wish to start with the irons for one reason or another, some may not. As such the rifle should have the ability to be easily configured as needed for the specific shooter.
With this in mind, I chose the following parts, pieces, and equipment for this basic build. I'll list both the MSRP for the part as part of the link, as well as my actual cost that I paid in parenthesis if it varies.
This includes the barrel, flash hider, front sight base, handguard cap, gas tube, barrel nut and delta ring, and upper receiver with dust cover and forward assist. This complete upper meets, or exceeds, all of the military requirements for issue M4 carbines. From the finish to the chamber, Bravo Company ensures that all of their parts and pieces used are of absolute best quality.
I chose to go with the midlength gas system for this rifle for a variety of reasons. The first of which is that I've never owned one. Secondly, and again because this rifle will be intended for new shooters, is that the longer gas system should, in theory, give a lighter recoil pulse which will translate to lighter recoil and faster follow up shots for the shooter. The lighter recoil pulse should also, again in theory, result in longer parts life due to less stress. Finally, the longer gas system allows for longer handguards while maintaining the stock front sight base and the longer handguards allow for a broader variety of hand positions and the potential for more mounting real estate later on.
This bolt bolt in this carrier group is properly HPT and MPI, and the gas key is properly staked in place. In addition the fully shrouded firing pin of the carrier cocks the hammer instead of the firing pin, and the added weight to the rear serves to increase the reciprocating mass thereby decreasing the recoil pulse with the same benefits listed above for the mid-length gas system
Given the mid-length gas system of the Bravo Company upper, handguard selection was somewhat limited. While I would have preferred to have a double heat shield in the handguards I could not find any midlength handguards with double heat shields. I chose to use the plastic handguards instead of a railed system in there interests of keeping the carbine simple and non-threatening to a new shooter, and because I didn't intend to attach anything to the handguards. The added benefit is that it keeps costs down on a basic carbine.
This was probably the least critical of the parts. I have lower receivers from several makers in my safe that are sitting around waiting for builds or one kind or another, and I frankly chose this one for the build largely because of the most understated logo. Yes, that's a stupid reason to choose a lower, but since the lower has become just about the hardest part of an AR to screw up, picking a lower from a field of quality samples really can come down to choosing based on logo. I've had this lower for so long that frankly I don't recall what I spent on it, but I'd imagine that between background check and possible transfer fees, the $140 number is about what I actually paid in total.
A typical lower parts kit from Stag or CMT would have sufficed for this build, would have run $70+/-, and would have come with an A2 grip. This kit cost $30 more and didn't come with a grip. So why would I opt to spend $30+ more if I didn't have to? A few reasons. First of all is the A2 grip. It literally does nothing for me. Getting rid of it is the first change I make to any AR carbine that I'm expected to spend more than a few minutes with. It is, in my opinion, the absolute worst firearm grip that I've ever dealt with. But virtually nobody sells a kit that doesn't come with it.
So did I pay more money to get less parts? In terms of quantity yes I did. In terms of quality, no I did not. Over the course of several builds I have come across parts that are all just not quite right. I have always been on the lookout for a lower parts kit that I can be sure is of just a slightly better quality such that the build goes that much smoother. When I saw that G&R was offering these kits I decided to take a chance, and I am not disappointed. Initial visual inspection of the parts shows that they are all of good quality, properly machined as they should be, etc. Aside from some learning-curve issues due to my not having assembled an AR lower from scratch in awhile, the assembly went off without a hitch.
Bill has gained quite a reputation in the AR community for his re-worked AR triggers, and I have been hard-pressed to find any complaints about him or his triggers (which is a rarity in the AR business). He reduces the stock, gritty trigger pull down to 4 lbs for $35 (recommended for duty and field rifles) or 3lbs for $49 (for target and long range rifles). I've been wanting to try out his work for quite some time and thought this would be a good opportunity since the parts are already out of the gun, saving me the trouble of stripping down another gun. I do think (hope?) that having a lighter and smoother trigger will aid a new shooter in getting good hits, and nothing builds confidence like getting good hits. I don't believe that there is a safety issue since the finger should only be on the trigger when the sights are on the target.
As mentioned above, the A2 grip is horrendous. Conveniently enough Magpul released their M.O.E. grip around the same time as I was putting this rifle together and I decided to try it out. At only $20+/- it's a good deal. My only gripe is that I would really have preferred it if they had addressed the gap between the trigger guard and the grip by molding a little extension in the grip to fill the gap. Fortunately the G&R LPK comes with the Magpul triggerguard which fills this gap. An alternative to both this grip and that trigger guard would be an A1 grip and Gapper which combined can be found online and at gunshows for under $15.
To sum up the grip/LPK pricing, I wound up spending $154 ($98 LPK, $21 MOE, $35 labor) on parts that I could have gotten for $72 ($70 LPK, $3 Gapper). That's an $82 premium that I would not expect other people to spend, or that they would need to spend. This is a splurge of sorts for me personally to take this opportunity to try some new gear and to make some basic improvements that are more easily made at this stage than later on. No matter what, however, that A2 grip would have gone in the trash (can you tell how bad I hate them yet?).
The Troy offers the ability to flip down out of the line of sight for a new shooter. While most of us that have been shooting ARs with RDS for awhile know that if the RDS is in a mount that puts the irons in the lower 1/3 of the optic then the rear iron will not be a factor, it can still be a bit of a distraction to a new shooter. Yes, a fixed rear BUIS like the Larue has the ability to be removed from the rifle altogether, but you then run the risk of the sight being lost. The Troy is not removable without tools and can be folded down out of the line of sight. It is also slightly lighter which is a plus on a rifle for a new shooter
The Aimpoint Comp C3 is the secret value of the Aimpoint line. Contrasted with the newer M4 and M4s models it is nearly 1/2 the cost. So what do you lose? For starters the C3 is not night vision compatible. It is also only waterproof to 5 meters as compared to the 45 meters of the M/L3 and M4 models. It comes with a mount that is useless for mounting to an AR and bikini-style covers as opposed to flip covers. The night vision and water resistance are non-issues for a rifle of this type as a new shooter is not likely to be using night vision devices or diving with the rifle. The water resistance is more than sufficient enough to keep the optic working in the rain. It is available in a 2 MOA or 4 MOA version, and I opted for the 2 MOA for this rifle.
The "high" version of this mount puts the centerline of the iron sights in the lower 1/3 of the optic tube, thereby keeping the optic high enough so that the iron sights do not obstruct the sight picture through the RDS and allowing the shooter to keep their head straighter while still keeping the rifle butt "in the pocket". G&R Tactical offers the ADM mount in a package deal with the C3 optic for $445, which is how I arrived at the $55 actual price for the mount. The ADM mounts have retained zero for me in the past both mounted and when removing and reattaching, and I like the reversible lever that does not require tools to adjust. With the throwlever mount of the optic and the larue iron sight, should the shooter want to "go basic/KISS" or want to lighten the weight of the rifle, the optic and mount are easily removed.
This is, frankly, another unnecessary expenditure. I don't even generally attach my sling at this location unless I'm running a single point. So why on earth did I cough up $50 if I didn't need to? Simply because I'm building the gun from scratch, and it's easier to put this part in now and get it staked properly than to have to take the receiver extension apart later on to add it. Having it there should also add some flexibility for new shooters as well to be able to try alternate sling mounting positions.
I have really come to like the two-point slings in spite of some of their shortcomings and the BFG Vickers quick-adjust happens to be my favorite. BFG recently came out with their "Victory" version with a slicker sling material and plastic hardware and which sells for about $20 less than the original version. Early reports on this sling have been good and I've been wanting to try one out. In the "budget" goal of this build saving the $20 seemed like an added bonus
Light & Mount
I haven't gotten to this part just yet, for a couple of reasons. One is simply one of cost. For right now I have multiple other ARs with lights on them, and nobody is asking to borrow this one for a low-light scenario just yet.
My plan is to simply install a short piece of rail, like the Streamlight Tactical Illuminator Mount to the handguards, and then buy a Surefire X300 to attach to that rail section. I have a similar setup on one of my SBRs and I think it works quite well. This should be especially true with the midlength as it allows the light to be mounted further forward and out of the way. The light will be mounted around the 10:30 position so that it is easily accessed with the non-firing thumb when shooting strong-side and the first knuckle of the strong hand when firing support-side.
This total package will wind up adding $250+/- to the total price of the carbine, but with the light easily removed it can also be used on other pistols and rifles when this one is not in use.
Total price, as built, and with sling is just at $1,600 and weighs in at 7.5 lbs unloaded.
