BrianKs .300Blackout build

I don’t do many builds so I’m documenting this as I progress. I was asked for a final picture after completion, and that’ll happen, but if there’s anyone like me reading this, who doesn’t assemble many ARs, maybe this’ll be of use to them. Rather than spreading out the build with many posts and having folks comment between them, I’ll come back to this first post and just keep editing and adding to it as things progress.

The handguard is a Lancer Carbon Fiber. I looked at various aluminum handguards at the local manufacturer/FFL dealer and their appearance had no appeal for me. Also, aluminum is very cold, sucking the heat out of the hands, and Maine gets very cold. So I really didn’t want aluminum; I try to stay away from it and hands as much as possible. Carbon fiber, done right, is quite strong. The Lancer handguard isn’t installed the same way a standard handguard is, the first part is glued in place. Follow the instructions for the handguard of your choice. There are installation differences even between other carbon fiber handguard manufacturers. This installation was different enough that at first I wondered what language the istructions were in. But sit down and slowly follow the instructions and you can figure it out, the same as I did. What was throwing me was the “extra” receiver extension nut and the way that Lancer had the barrel nut threaded into it for shipping.

First the receiver extension nut is screwed in place on the lower after having prepped the threads on the upper and inside the extension nut. That consists of removing/breaking through the anodize specifically designed to resist exactly that. I tried the suggested Scotch Brite and that didn’t work worth a damn. So I resorted to using a scribe (a sort of pencil for metal marking) and an automatic center punch. Eventually it was prepped to my satisfaction. The nut needs to be lined up with the gas tube and the rail on the handguard needs to be lined up with the rail on the upper as the red loc-tite cures. The gent at the local manufacturer suggested forgetting about the gas tube holes and line up the rails. The gas would fix itself if that was done. That made sense to me so I put the handguard on the nut (temporarily), breadboarded it and sure enough that worked fine. I like to clamp things so that was next on my list of things to figure out. Then it struck me. Rather than having all sorts of clamps possibly damaging things I had the Comp M4 seen in the picture. That has a sorta longish edge and as the sight is clamped down it aligns the rail in both the side to side and vertical axis’. One clamp that does both axis and its built to damage nothing. Slick.

So after degreasing the threads it was time to apply the Loc-Tite and clamp it up for the cure time. The picture was taken after removing the clamp (the sight) today.

The handguard is in place on the receiver extension nut seen as a sort of cone butted up against the stripped upper, but the screws aren’t in place holding it on, and the over the barrel can (Amtak CQB-M) that the pistol will wear 100% of the time is just placed in it’s approx’ orientation inside. It’d going to be a fairly short suppressed rifle should I decide to change it’s status from pistol to SBR. But at birth it’s going to be an arm braced pistol. The rail and gas tube holes are in perfect alignment at least as far as my eye can determine by sighting down both rails. Too, the Comp M4 is the sight that it’ll wear at least at first since it does NV and this will be so equipt.

When the barrel comes in that work can be done. The low gas block needs to be positioned, the gas tube put in place, and the barrel torqued down. Unseen above, hidden by the carbon fiber handguard itself, the barrel nut is screwed into the receiver extension nut. It’s just a good place to store it right now as it waits for the barrel.


Sexy handguard whats the weight?


Good question Robert. I didn’t weigh it before mounting it though, and now I can’t. It’s permanently attached unless I put a heat gun to it to break the red Loc-Tite. The Lancer website only lists the weight of the 15" model and that’s 1#. The 12" seen here would be slightly less of course, but not wildly less. Most of the weight is in the solid metal pieces.

I didn’t choose it for weight or I’d have gone with another Brigand Arms, and almost did. Since the can is right under the handguard and they get hot I wanted to protect my hand. I just accepted right up front that this wasn’t going to be a lightweight build. It’ll probably wear the can 100% of the time and that adds substantial weight (17 ozs). Add a can to almost anything and it’s felt to get much heavier, throws the balance way off too. I expect this to be quite muzzle heavy with the can and barrel, except the weight won’t be “way out there” as with a rifle of conventional design (ie. not a bullpup). I expect this to be a heavy pistol for it’s size. That’s one reason it’s also going to use the Aimpoint. There is no pretense to light weight, just functionality. The Aimpoint does NV really well and has infinite eye relief for any way I wish to hold it. But a micro red dot it isn’t.

For a time the MDR wore that can and there just wasn’t much of a balance shift. Some shift, to be sure, but not as much as I would have thought. But of course that rifle is heavy to start with since it’s actually a .308 converted to, in my case, .223.

I will get a barrel extension if I don’t have one that’s long enough to clear the handguard for the very few times I might not want the cans weight. That might happen if I take up deer hunting again. The handguard would make for a very short lived flash hider. It’s not designed to withstand blast inside it and I don’t intend to ever test it. I don’t want to be forced to buy another. It was more than I wanted to spend but right now it’s a sellers market and not a buyers market. Everyone is out of stock on most everything worth having. I was lucky to find certain items that were non-negotiable, like a good CF handguard and a BCG with an easy clean finish and a tough bolt. I expect the BCG to get one heck of a shot of gas with that short gas tube.


Progress points:

Talked with a machinist about the muzzle extension for the few times that the pistol won’t wear the can. It’s in the queue but it’ll take time for him to get to. I need to furnish dimensions after getting the pistol in hand.

The JP Enterprises BCG came in and it looks really nice. By far the best BCG I ever bought. Fingers crossed that it easily wipes clean and in a move to keeping it cleaner…

Educated myself about buffers. Since I expect the BCG to get a significant shot of gas with the gas port so close to the chamber. Learned that the right weight buffer will help to keep the innards cleaner by holding back the BCG. Maybe that’s why my rifles when suppressed get so dirty? Anyway, 2 KAK configurable buffers are on order. I have one rifle that the Enidine (see below) came out of and the ejection pattern changed significantly. It needs a heavier buffer, the BCG has too much speed (ejects forward around 1:00).

Went rummaging through parts and found a Enidine hydraulic H2 weight buffer. (no longer available)

The local manufacturer is expected to have my lower assembled today. It would be nice if the barrel came in for completion this week. I’m looking forward to it. There are required but minor odds and ends that need to come off of their shelf for the build.


How about some photos, have you never had an LWRC to campare?


No I never saw one.

Frankly, for this build I wanted a Geiselle, but they didn’t know when they would be available and I wasn’t going to get involved in yet another waiting game the way I did with Desert Tech. The JP uses better steels where they are needed and has some sort of super coating (QPQ, PQP, something). It feels like glass. I know both Giesselle and JP coming from my competition background. You’d think I’d know LWRC from my days carrying a M16 for Uncle Sam, but they came in the picture many years after I got out.

edit: The JP BCG (full mass op’ system) cost me a bit more, but after the “honey” app found coupons for me it wasn’t enough of a difference from the Geisselle to matter on a build like this.

Incredibly difficult to take pics of and see anything. The BCG is jet black. In order to see anything more than “black” I had to severely adjust the exposure in photoshop. It appears greyish, but again, is jet black. Sorry for the out of focus pic of the Enidine buffer in the spring.

edit: I just got off the phone with the local manufacturer and the barrel came in, so everything is in hand. Now it’s just a matter of putting everything together.


OK, I changed my mind, I’ll just keep adding to the thread and not to the first post in this thread.

Did I mention I don’t do many builds!?? I screwed up. I didn’t install the dust cover before the handguard nut. I could have pulled the C clip from the dust cover shaft but it’s tiny and I don’t trust my hands to get it back in place, so instead I heated up the receiver extension nut and removed it. My old hands had one heck of a time handling the dust cover spring under tension, and I wound up clamping a hemostat to the short end of the spring and with the wife pushing the rod got it in place. The C clip might have been easier but I’ll never know. More red loc-tite on the extension nut and now I’m waiting for it to fully cure again. I actually checked it 5 hours later and due to the warm day and putting it in the sun to warm up it’s acting cured, but I’m going to wait until the morning to make final moves on the build.

The Ballistic Advantage barrel…

Very nice barrel. It came with a gas block which has set screws and is machined for a pin. It looks like a high quality barrel and the local manufacturer who ordered it told me that I would like it. Yeah, I’m not disappointed. Clearly they’re getting to know me.

I did remove the gas block from the barrel and ran the barrel nut up but didn’t torque it. I set the handguard in place and ran the can into place. It fit fine with enough clearance. I had some doubt due to inside threaded pieces that hold the rail onto the handguard, but they left enough room and I had no problems. There is maybe 1- 1.5" of can protruding past the end of the handguard. Excellent. Looks fine, like it was intended to look that way (it was). I didn’t want a fugly handgun.

I also worked on the lower. I wish I could remember whose lower parts I bought those years ago. But that information is lost in time. Windham Weaponry? Maybe, probably. The trigger is nice. Heavy, but not as bad as GI. I was expecting much worse. I’ll need to live with it a bit to see if I can get along with it.

I put the SB Tac’ brace on the lower using hand sanitizer as lube. Then put the charging handle and BCG into the upper and assembled the entire pistol to fully check things out. It should work fine. I left it that way just long enough to check things out. No lube in it and the BCG feels like it’s on ball bearings. Between the finish of the BCG and the NiB coating on the barrel, if I pull a pin and hinge open the upper and lower the BCG comes sliding out without help and without much of an angle for gravity to pull on it.

OK, done checking things, I kept the barrel in place and removed everything else. I did remove the standard buffer and put the Enidine H2 buffer in the lower. Due to the frictionless action of the BCG I think I’ll need it. I’ll torque the barrel down tomorrow and finish the build.

The parts I haven’t identified:

The can is an Amtak CQB-M 30 caliber
The upper is an Anderson and the lower is made for my local manufacturer and has their brand on it.
The charging handle is a POF Tomahawk.

I haven’t forgotten a finished picture. I also need to weigh it. It’ll all happen in due time.

In checking it out sorta fully assembled it’s nowhere near as heavy as the MDR would have been with the conversion barrel, but I knew that going in. It might be shorter than the MDR would have been with the can in place too. Since the .300BLK doesn’t need a long barrel it loses little or nothing with a 10" barrel, or so I’m expecting.


FYI this dust cover uses a spring loaded end and does not require taking things apart. I have them on several builds. And they come back off easy too.

Next time!


The pistol is mostly finished!
The sight is a Aimpoint Comp M4. It’s a bit low for me so I either need to raise it up or buy another sight, it will be smaller if I go that route. I think I’ll just raise this sight since this sight does NV. Yes, the Lancer handguard is rock solid so it makes a good base for the sight. I’ll need to figure out final positioning with NV in place (pvs14).

I’m going to compare this firearm to the MDR which was what I originally wanted, but Desert Tech couldn’t supply after 4+ years of waiting on my part. (But retailers had them!)

The arm braced handgun:
length with can: almost exactly 30"
weight with can and sight: 7# 10 3/8 oz

MDR in .223 Wylde :
length: 27 3/4", but with the can attached add 4" for 31 3/4"
weight with a lighter MRO and no can: 9# 14 3/4oz add another 18 oz for the can for 11#

MDR in .300BLK:
Nonexistent after 4+ years of being completely paid for.

The MDR can’t be used with a drum mag and the handgun can be. The MDR does have a much longer barrel but I don’t think that will be much of a factor for .300BO. Plus I reload so I can tailor my ammo.

I haven’t fired this yet (soon). But right now I’m actually happy that Desert Tech couldn’t/wouldn’t (I don’t care which at this point) fill their part of the bargain struck 4+ years ago. I have a shorter and significantly lighter firearm. Of course one is a rifle and this is a handgun, but I tried as much as possible to compare what I could as best I could.
(Middle finger salute emoticon to Desert Tech goes here)

Photographing a black object? Very difficult to get anything more than a silhouette. Trust me on this, it’s actually black. It appears grey here because I over exposed 2 f-stops and further adjusted the exposure in Photoshop.


Nice looking pistol @BrianK!


Nice job @BrianK !!


Thanks gents!

I’ve put exactly 2 rounds through it. I wanted to make sure it went bang and I wanted to see if the buffer weight was even close. The first round was supersonic and the 2nd subsonic round was picked up. But the bolt never locked to the rear after firing it. It needs a lighter buffer. I put one in and haven’t shot it again. I have 2 weight configurable buffers coming in.

Too, I picked up a riser and that puts the sight in a much better position for me.

It’s the first .30 bullets that have been put through the can. I know why its called the CQB. That’s what it’s designed for, not blasting ones eardrums if using it indoors, but civilians generally want better noise suppression. I’ll need to wear hearing protection even with the can in place unless I’m shooting it during a social disturbance. But that’s exactly what I wanted… a short over the barrel can that removes blast. I have yet to test it indoors. I knew I wasn’t going to test it indoors with .223.


As I already wrote, I don’t do many builds so this is quite an education. Thank GOD for the internet! It allows me to find out how I screwed things up. Nothing major though and easily fixed.

Rifle length springs vs carbine length springs, who knew? :smiley: I didn’t, but I do now.

I was getting short stroking and the BCG wouldn’t lock back. Internet to the rescue to find the problem. I have no carbine length springs (2 on order now) so I cut 3 coils off of a rifle length spring. It appears to work fine now but I need to shoot it some more and put a real spring in it. I’m going to hold off on anything more until I get the spring(s). I need to revisit the buffer weight.


What do you need to change about the buffer weight? A heavier buffer will slow the BCG down. If you go overboard with the additional weight there is not enough gas to lock the BCG back.


I just want to revisit the buffer weight, basically just step back a bit and observe. I’ll know more when I see where it’s ejecting the brass and I haven’t done enough shooting of it to see that. I tested it with a brass catcher on it and I need to remove that. Since it’s going to wear a can almost all of the time I really want to cut down on the gas that comes back through the breech. The biggest thing I dislike about suppressors is the increased soot buildup. If I can reduce that a bit I might not have a smile on my face, but it’ll be better. One thing at a time though. Get in the real spring and not use a clipped one and notice the ejection. If the spring works but the ejection is off, then work on the buffer weight to fine tune it. My hope is that I touch nothing about it.

None of this is big deal, no big production to do any of this. I just walk out of my shop and my range is yards away.


Some folks are using adjustable gas blocks so you can adjust the gas when you go from can to no can. Enough gas unsuppressed is likely overgassed suppressed.


I’m hoping I don’t need to go that route. As I wrote the aim is for the can to be worn most of the time. That wording gives me wiggle room. The plan is for a can to be on it 100% of the time, either the Amtak or the Ghost-M. But the Ghost can only handle subsonic, the Amtak anything that’s .30. It’s pictured somewhere in the thread with the Amtak in place.

I’ll see what I see when I get there.

Here it is with the full length Ghost-M in place. The seam can be seen where the short configuration would end. About 1/2 way up the exposed section of can. It’s not easy to see, but it’s there as a slightly darker line. It looks much better with the Amtak, but that can is just for blast. It’s not civilian quiet. It’s pretty much flow through too. The Ghost has much more back pressure and is quieter with it’s wipe in place. It can be run w/o the wipe.


Is there a reason why the optic isn’t mounted directly to the receiver? I’m not used to seeing optics mounted so far forward.


It’s not in it’s final place yet, but it will be forward more than what would be considered normal for most folks. I have a night vision option that will go directly in front of the eye and pick up the image projected from the sight. That sight has infinite eye relief so it works placed anywhere on the rail. But put it in place, sight it in and leave it alone, more or less. It will return to close to zero if removed and placed in the same spot on the rail. I’ll put “blanks” on the rail to mark it’s spot fore and aft.

There’s another reason too. I like sights placed forward if I have my choice. It’s a “scout scope” placement, sort of, and it gives (IMO) far superior peripheral vision. Not all 'scopes are capable of that but I can’t recall any modern 1x red dots that don’t have infinite eye relief and are capable of forward mounting. Having an optic forward is really little different than having an iron front sight. Like an iron sight, put ones head in position and it’s “right there”. I’ve handed my competition guns to other shooters to fondle and they pretty much all say the same thing, “It’s right there.”. You aren’t alone in thinking it odd though*. While I’m shooting the current target I can be seeing the next one to get ready for it, using both eyes, as long as I’m not in tunnel vision. That’s the best I can describe it.

*I always tell people to set their firearms up as THEY want it and not as others think it should be. Firearms are as individual as underwear and what works for you works for you. No need to justify it. But sometimes it might take an explanation which is perfectly OK. :yep:

It’s like a slung rifle. For some reason “everybody” needs to carry a rifle barrel up. I don’t get that and never did. Slung that way getting into position for a shot is slow and the rifle always is a PITA to carry because the barrel is the heaviest part and wants to rotate down. It’s OK on a parade field when the troops are in formation and everyone needs to look identical. In the field in the military I always carried my rifle barrel down. Less crud gets in it that way. Today I carry a slung rifle cross body up front. I can raise it really fast and it doesn’t point at anyone I meet to talk to. The reason I bring it up is that it too is what works for me. It might not work for others, but it’s my “underwear” and personal to me alone. Don’t be locked into doing what others think you should do, do what works for you is my point.

Back to the sight. I did consider putting a smaller red dot on it, still forward mounted, but I want to keep the NV capability. I know of no rugged micro red dots with NV capability.