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I’ve already got my upper and lower and lower parts kit. I’m going to use the KAK shockwave blade and tube like I did on my Ar9mm pistol build. I need suggestions on a BCG and an optic. I’m really considering going with a primary arms 1-6 or a vortex sparc 2 as I already run one of my AR 9mm pistol build and really like it. But I’m open to others. I’m not super well versed in the Optics/BCG world.

OK.... this is just me, and I might be off my rocker, but I don’t get putting a magnified or variable power optic on an AR pistol. Unless you’re going to shoulder it and shoot it like a rifle, I don’t think you can really take advantage of a magnifying scope. OTH, a good red dot is a GREAT choice in such an application. I have a 10.5” SBR in .300 Blk, and I keep an Aimpoint T2 Micro mounted on it, and it has worked fine for me, even though this is a rifle, fired from the shoulder. But, I also own a Primary Arms Advanced Micro Dot (essentially the same thing as the Aimpoint, currently mounted on a Keltec 9mm carbine at the moment), which costs less than 1/4 of the Aimpoint T2’s price and seems to function about as well under “normal” circumstances. Don’t get me wrong; the Aimpoint product is a very nice RDS. Very nice. But I don’t know if the T2 is any more waterproof or shockproof than the Primary Arms RDS....maybe it is....but unless you’re going to be shooting it underwater, who cares? And it’s not like .300 Blk recoil rivals a 91/30 Mosin Nagant destructive device, so that’s a non-issue.

So synopsis: Get a red dot for your AR pistol, and don’t bother with a magnified optic unless you’re going to shoot it from the shoulder like a SBR.... And make it a Primary Arms Advanced Micro Dot instead of an Aimpoint.

BTW, here’s my reasoning on why it doesn’t make sense to use a magnifying optic on a AR pistol..... Versatility.

You have two basic choices in a magnified optic for an AR pistol: either a long eye-relief “scout” type of scope; or a short eye-relief “normal” scope. If you put the long eye-relief scope on the pistol, it will work well if firing the pistol like any other pistol, with the arm(s) extended out away from your face. But if you bring the short little stubby “brace” into your shoulder like a rifle stock, your eye will be too close to the scope for the scope to be usable. The exact opposite is the case for a “normal” eye-relief scope. It will work fine with the brace shouldered like a rifle stock, with your eye closer to the ocular lens, but it will be unusable with your arms extended, holding it like a pistol.

Ergo, avoid magnified optics, and go with some kind of RDS.

I agree with TAM. I can't comment on the battery life of other red dot's but my Aimpoint PRO on my AR pistol that stays in a backpack in the car is left on constantly. I change it every 6 months or so just to be on the safe side due to extreme temperature extremes.

BCG depends like everything, how much you want to spend. I have one from Aim Surplus that cannot complain about. They have several different options in coatings and would be a less expensive option. Of course I'm happy with the Fail Zero I have as well.

As far as BCGs go, any old normal AR15 BCG ought to work just fine, so unless you’re trying to pimp this thing out, I’d just buy whatever you can find at a decent price on Brownells.com or MidwayUSA.com (or whatever your normal preference happens to be for buying AR parts). One suggestion - your .300 Blk is going to run a bit dirtier than usual because of the abbreviated pistol length gas system. So it might behoove you to pick a BCG that has been NiB or NiPh coated, as it will make cleaning it easier.

The Annoyed Man wrote:OK.... this is just me, and I might be off my rocker, but I don’t get putting a magnified or variable power optic on an AR pistol. Unless you’re going to shoulder it and shoot it like a rifle, I don’t think you can really take advantage of a magnifying scope. OTH, a good red dot is a GREAT choice in such an application. I have a 10.5” SBR in .300 Blk, and I keep an Aimpoint T2 Micro mounted on it, and it has worked fine for me, even though this is a rifle, fired from the shoulder. But, I also own a Primary Arms Advanced Micro Dot (essentially the same thing as the Aimpoint, currently mounted on a Keltec 9mm carbine at the moment), which costs less than 1/4 of the Aimpoint T2’s price and seems to function about as well under “normal” circumstances. Don’t get me wrong; the Aimpoint product is a very nice RDS. Very nice. But I don’t know if the T2 is any more waterproof or shockproof than the Primary Arms RDS....maybe it is....but unless you’re going to be shooting it underwater, who cares? And it’s not like .300 Blk recoil rivals a 91/30 Mosin Nagant destructive device, so that’s a non-issue.

So synopsis: Get a red dot for your AR pistol, and don’t bother with a magnified optic unless you’re going to shoot it from the shoulder like a SBR.... And make it a Primary Arms Advanced Micro Dot instead of an Aimpoint.

I agree - a red dot works perfect.

I agree I think the red dot of some sort will be what I go with. What’s one that can be left on all the time with good hours

If you are going to leave it on for defensive purposes, get back up irons. Magpul MBUS are very popular and for a good reason. I wouldn't rely solely on a battery if my life was on the line.

Aimpoint is known for battery life. Unfortunately they are pricey and the models with exceptional battery life cost a lot. I personally know soldiers who turned their Comp M4's on when they landed in great litter box and never turned them off until it was time to leave. That is why I put an Aimpoint on mine but I couldn't see spending what I spent to put the pistol together on a red dot, so I went cheap and got the Pro. I leave mine on 7 or 8 and just replace the battery every 6 months. I'm not sure how long it will last but I'm not chancing it being dead when I need it. My backpack goes in whatever vehicle I'm driving and sometimes gets worn in public.

Ammo, I keep 20 rounds of Barnes VOR-TX in the pistol and 2 30 round mags in the pack with room for another 30 round mag if I want.

I agree with what you said about the back up irons. I use the magpuls your talking about. They are great sights. And will for sure have them on the 300. And I was just about to ask about the ammo. Should I play it safe and run SuperSonics? I will suppress it from time to time and use the subs but for reliability reasons will the supers be the better choice for all the time use

Not exactly related to BCG or optic but is relevant to a 300 pistol. A friend of mine built a 300 pistol and had a lot of issues getting it to run right. Finally got a H2 buffer and put in it, so you might want to start with a heavier buffer as well.

I run supersonic as it is not my home defense weapon so I'm not worried about the noise. Until suppressors are taken off the NFA, I will not have one but that discussion is not for this thread. All I know about sub reliability is what I've read and will let somebody with actual knowledge chime in... TAM in 3,2,1...

Medley86 wrote:Not exactly related to BCG or optic but is relevant to a 300 pistol. A friend of mine built a 300 pistol and had a lot of issues getting it to run right. Finally got a H2 buffer and put in it, so you might want to start with a heavier buffer as well.

Mine was dinging the cases at the mouth from hitting the brass deflector. H3 buffer and Sprinco blue spring smoothed it out. I don't expect it to shoot subs unsuppressed but I haven't tried either.

jason812 wrote:

Medley86 wrote:Not exactly related to BCG or optic but is relevant to a 300 pistol. A friend of mine built a 300 pistol and had a lot of issues getting it to run right. Finally got a H2 buffer and put in it, so you might want to start with a heavier buffer as well.

Mine was dinging the cases at the mouth from hitting the brass deflector. H3 buffer and Sprinco blue spring smoothed it out. I don't expect it to shoot subs unsuppressed but I haven't tried either.

My friend shoots subs unsuppressed with the h2, not sure what spring he runs. And we are somewhat assuming that they are subs, he is handloading 220 grain hand poured to a load that is supposed to be subsonic. Seems to run everthing ok now, he hasnt sent in the form 1 to build a supressor for the 300 yet though, so not sure what it would do through a suppressor.

jason812 wrote:TAM in 3,2,1...

Subs run very reliably in my .300 Blk SBR, but not so much in a 5.56 weapon. Some people have questions about the terminal ballistics of .300 Blk subsonics, but that has to do with bullet design, rather than velocity. At home/personal-defense distances, a heavy subsonic weighing 208 grains is going to be going around 1,000 fps. That's in .45 ACP +P territory, which is certainly capable of a one-shot stop if bullet design and placement are optimal. Obviously, an FMJ is just going to poke through. At subsonic velocities, it probably won't even upset, yaw, and do the kind of damage that higher velocity FMJ rifle bullets can deliver. BTHP bullets like SMKs and A-Maxs might deform more, but they still mostly perform like FMJs. OTH, if you poke a LOT of holes in someone, they'll usually sit down and take a breather.

There are high performance subsonic self-defense loads available on the market, but they are quite expensive. Outlaw State makes heavy self defense bullets for subsonic use that look like they would perform well (http://outlawstatebullets.com/2.html) if you don't mind hand loading your defense ammo.

Lehigh Defense has a subsonic load that performs very well in self defense, but it is kind of pricey at about $40 a box. https://www.lehighdefense.com/products/ ... 1066138648
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