300 Blk AR Pistol build observations

[HiBC]

I'm not an expert on these. Stumbling through my first AR pistol build.
These days,with a lot of "out of stock,no backorder" a certain amount of flexibility is necessary.
I suggest carefully reading and understanding the BATF 2017 memo on AR pistols. There are some helpful vids on youtube.

BBL is a 10 in Aero

Handguard is a slim Midwest with a top rail only,M-Lok I forget exact length. About 8 in.

AR Stoner muzzle device. Linear. 5/8 24 thread. Looks like a 2 in long,slim 22 cal revolver cylinder. Blast blows downrange. No side ports. 20 something dollars.

I have a fixed detachable handguard mount front sight. I have a XS Sights tritium white stripe front sight post.OK,I initially bought a SARCO carry handle,figuring on chopping it for a rear sight. 30 some dollars. Height is short. Darn. I ordered another handle from Aero. Its coming.
Then from Midway I bought a off brand (Maybe UTG? $18) fixed front handguard rail sight. Amazing! Its short height,too! My plan almost came together. Almost.

The UTG front sight base offset the detent 45 deg for real estate reasons. Thats OK with a round front sight post.

But I had ordered an XS sights tritium front sight blade. Won't work with a 45 deg offset detent.

Was considering just cutting a new detent notch in the XS sight. So,I'm thinking about breaking the tritium vial when I put it in the mill vise...and I remember the Aero carry handle is coming. Hmm. Its probably a better rear sight than the SARCO. It will be standard height. OK, I put myself on the "notify" list at Midway for either a Daniel Defense or Midwest fixed front sight base.
Why didn't I just go with a Daniel Defense or Midwest rear sight? Fair question. "Not in stock" played a part.

A regular sight post will have 4 detent positions,each (IIRC) 1.5 MOA with a standard sight radius. The tritium blade requires a full rev of adjustment,or 6MOA at normal sight radius. The pistol,with shorter sight radius,will be a coarser adj. Maybe 8 or 9 MOA per full rev "Click" OK for bore sight,but I want elevation clicks in the rear sight.

I want rigid,vs folding sights. The Daniel Defense and Midwest rear sights have no elevation adj.

I ordered the Aero carry handle and I'm going to chop it ahead of the rear clamp. Brother is set up to Cerro-Coat. I also ordered from XS a replacement modified flip/flop rear aperture. I got the one with the open sight notch added on top.

Why? Read the BATF 2017 memo about AR pistols. Speaking to placing a pistol brace on your shoulder,they said if the brace was engineered for pistol use,the incidental placement on the shoulder did not re-engineer the brace.

OK. The point,f
Features of the gun must be engineered toward pistol use. They even say "Holding it one handed" Any feature that would dictate firing it from the shoulder is potentially a problem.

My interpretation,if I use the standard dual aperture flip GI rear sight insert... I just cannot see through the peep if I hold it out as a handgun.

Potentially,if I met the right (or wrong) LEO or Agent, with peep apertures,
a case could be made that my pistol was non-compliant. Rifle sights. Not useable for pistol use.

By adding the open sight notch equiped insert, my rear sight is handgun appropriate.

I'm just trying to stay out of trouble. Tritium irons will do for now.

And I have the front sight set back a little over 2 inches on the top rail.

I'm thinking,later on, a compact 500 lumen Shurefire laser/light will fit there.

I figure I could probably ID my target with a smaller 75 lumen light,but I imagine its a lot harder for the threat to aim at a 500 lumen light than a 75 lumen. His eyeballs might start smoking.

I put a Magpul M-lok Angled fore grip on it Between the handstop on the AFG and using the front sight post as a top handstop, My left hand knows where to be. Especially since I put a Magpul steel sling attachment ring for the HK snap hook a little over 3 in from the rear end of the forend on the top rail. It might be hard to envision.but if my left hand find the sling,it slides down the sling to find the same grip on the forend ,AFG,and sight post every time.I need a section of rail cover on the top rail behind the front sight.

Brace is a Tailhook. Its mounted about 1 1/2 in fwd the end of the tube.

Its rigid,but opens like a pocket knife opening 1/2 way. I like it. No strap to mess with. I can hold this contraption like one handed bullseye shooting. Compliance! I may put a crutch tip on the end of the buffer tube.That way it will be less "scooty" if I lean it against something.

I figure I'll keep a 2017 BATF letter in the trap grip.

Harbor freight had the little $37 2 in blade chop saw back in stock for cutting 5,56 brass to 300 blackout. The fixture designed to work with that saw to cut 5,56 brass to length was on Amazon for about $20.Forming is essentially necking down the case body from approx 35 cal size to 30 cal size.No big deal.Trim and chamfer,of course.

I found a 4lb jug of Lil Gun. And Speer 30 cal 125 gr TNT bullets for $ 20 a hundred. Got a few Nosler 125 gr BT's,too.

The plan is coming together.

I had some false starts,and wasted some money on junk. Its hard buying stuff online you cant touch. And buying cheap does not often work out.
Before you tell me "Why didn't you just...." Because I was finding my own way.
I figured I'd write this to share my wrong turns and the things that worked.

At some point,it will likely get a Streamlight laser/light ahead of the front sight on the top rail. My thumb will be in the right place to operate it.

And I may try a red dot on it,too. But it will be a while. Wallet is getting thin.

Oh..Trigger. I decided to try the cheaper Timney monoblok trigger. I wanted a single stage and short reset,not too light. As far as pull,I think this trigger will be fine. Hammer is wired EDM'd S-7 and sear is CNC A-2. IMO,those are optimum steels and processes.
The only annoying thing about this trigger is tightening some setscrews that are placed inside the trigger monoblock under the tails of the hammer spring.

As you can't put the allen wrench through the wire of the hammer spring,the tail of the hammer spring must be lifted to gain access. Once you get that done,you have to go back and install some little bitty jam set screws on top of the screws you just tightened. It will be OK,but its not a piece of cake.I am waiting on cerro coating the mis matched green lower I had in stash. Brother does that. No point in assembling it twice.

 

[zoo]

Shoulda gone with 350 Legend.

 

[HiBC]

Shoulda gone with 350 Legend.

You go right ahead!! Enjoy!! I'm sure you have your own good reasons!!

If I had it to do over again,I'd still go 300 BLK.

But I understand ,for some applications,350 legend might be more suitable,

And I will treat you and your choice with respect.

 

[44caliberkid]

I used a red dot with a built in laser on my 300 Blackout, dot for most use, laser for maybe indoor defense use. You could have gone with Magpul polymer pop up sights, not real expensive and I've used them on carbines. I think that 2017 letter (policy) has changed at least twice. You could always use two hands, one on the grip and one on the forearm, couldn't use a verticle forearm grip. Eventually there was a written opinion that a gun couldn't be legal or illegal by how you hold it. Then that was later modified to say you couldn't use an arm brace against your shoulder, like a stock.

 

[HiBC]

Agreed there are a lot of folding sights available. They would work. I could have just ordered a matched set and come out cheaper. I appreciate that.Thanks.

For myself,flippy/floppy ,up,down complexity,little plastic parts,....I just prefer to have simple,rigid sights. And I wanted tritium.

If I had it to do over again,I think I'd end up with the same combination. I just would not have wasted time and money on the Chinese stuff.

For myself,magnified optics,like a scope,are out due to fixed eye relief.

So,for sights,its either red (or green) dot,or iron sights.. I had a Vortex Strikefire red dot on it for a day. It just took too much force...I'd guess 30 lbs,on the +/- button. I gave it a "No confidence" vote. My LGS sales person agreed and cheerfully refunded my money.

For now, I'll have fully adjustable rigid iron tritium sights.

I can worry about red dots,lights and lasers later. I do have a 200 lumen flashlight in a QD Leupold scope ring. I can attach a short piece of picatinny (which I have) to the side of my forend,and bingo,a weaponlite.

And on another AR,I have a nice,flat,compact Laserlite red laser tucked under the objective bell of the 2.5-8 Leupold MilDot. I can cannablize it if need be.

FWIW, in full dark,using that light and laser,on a 100 yd target,the light is plenty. I can see my scope reticle and the target. The laser spot on the target I adjusted to cowitness my crosshairs.
That setup works. I'd like to leave it where it is.

But Thanks!!

 

[jonnyc]

Wow...way too much to read. WAY too much mental power wasted above.
I put together a 10.5 in. 300 BLK pistol, with a simple red dot on top and non-folding 45 deg. irons. No fuss, no muss, no unfolding, etc. Perfect gun.
Only issue...I can't get no subsonic BLK ammo!!!

Forgot to mention the perfectly measured and situated brace!

 

[wild cat mccane]

Even gun enthusiasts aren't confused that an AR pistol isn't for the joy of pistol shooting. If the law changes on these to make all braces sbr and the sbs (short barrel shotguns with the raptor head grips), I wouldn't shed a single thought.

That's a lot of text to avoid an SBR for $200 and obviously save yourself concern about committing a United States federal crime.

 

[zoo]

I really like AR pistols. Not that big a deal to change out the brace and barrel if the law changes.

 

[dyl]

I also "built" a 300 Blackout pistol, 10.5 inch barrel, 9 inch Aero handguard (with the full length top rail), Nickel Boron bolt carrier group. SB4 brace. Vortex Sparc AR, Magpul BUIS, Magbpul Mlok angled foregrip, Streamlight HL-X laser/light (this one may need to go someday... heavy)

Finding subsonic ammo at this point in time, well good luck. I am still working up the quietest subsonic load possible with ~210 grain (or is it 215?) powder coated bullets. But it's been a couple months since I'd gotten busy with other things so I forgot where I left off. Ammo was also so expensive that I've only purchased 2 boxes of factory ammo for it, reloading was always in the plan. I think I was using H110, with pretty acceptable standard deviation in subsonic velocity.

Regrets: After attaching a silencer (Silencerco Hybrid) with an ASR (Silencer's "quick" detach mount), the length has grown substantially. I think I'm nearly at 16 inches again and it's front heavy.. maybe 14 inches? This was going to be an indoor HD long gun someday. I think an ~8 inch barrel, and sticking with direct thread mount will cut at least 3 inches off. I won't do it at this time because of cost and business but it would mean a new barrel, gas tube, handguard, and working up loads (maybe) again... I just don't feel up to it right now. I'd probably be able to get most of my money back selling the parts off. If an 8 inch barrel was substantially louder than the 10.5, I'd regret changing anything.

Too many gizmos: I got a light. With a laser. It is big and heavy. And the second red dot makes the Sparc AR a little confusing to look at. But hey I had to try it once

I think the solution is to lift more weights

 

[HiBC]

dyl...seems like you have a slightly different vision and a reasonably similar approach.
Build it,see what works,or not,change it.

I can't afford a silencer,and subsonic is not my priority. But you have fun!.

A bullet that may be interesting ..I think its a Hornady...a rubber tipped bullet with a long boat tail...165 gr I think. Its designed for the 30-30 so it may perform at lower velocities.

I'm starting with 125's and LilGun.

On youtube they detail making brass from 5.56. Its very straight forward.

I found the 2 in jeweler saw chopsaw back in stock at Harbor Freight for $37.

The brass holding fixture was on Amazon for under $20.

Pretty much the shoulder gets chopped off the case body. You get roughly a 35 cal case body and your sizing die necks it down to 30 cal. There is a little trimming and chamfering involved.

I got TNT bullets for 20 cents. Its reasonably cheap shooting,IMO.

Hey!! Thanks. You understand I was sharing the good,bad,and ugly

So you told me what you are doing. We can both learn.

The critics can go away. What good are they?

 

[dyl]

I absolutely understand you were sharing your experience (and not necessarily asking for advice) because putting together a 300 blackout *is* an experience. Lots of decisions to make along the way. Almost too many choices to make. Ordering parts sight unseen is always risky. And since it's an AR, things can always be changed later which may be a curse for those who like to tinker but have other things they should be doing with their time!

Yes, I've converted maybe 20 .223 cases to 300 blackout, I size them on an RCBS Rockchucker Supreme. Once I forgot to switch out my shellholder from 9mm to 300 blackout, so I learned how to put together a stuck case puller kit.

I usually use a Dremel and it's cheap but slow and difficult to cut straight. For now it works as long as I just do a case or two at a time. Do you know what the case holding jig you found for the chop saw was called? I understand they are not all made equally, some jigs account for the slight taper in the case, some don't. (unless I'm remembering wrong, in which case disregard)

I'm thinking about switching out my M-Lok AFG because it's a very shallow angle compared to the larger AFG's. I might go with hand stops instead because I think I could keep my wrist more neutral with the right technique. Wrist seems to get bothered if I do a lot stuff at the extreme range of lateral motion.

Well done, and thanks for sharing your experience.

 

[44 AMP]

Potentially,if I met the right (or wrong) LEO or Agent, with peep apertures,
a case could be made that my pistol was non-compliant. Rifle sights. Not useable for pistol use.

Wow.

Personally, I think you are waay overthinking the risk.

First, you'd have to run into 2 people, the agent, AND the prosecutor who both hold the OPINION that "rifle sights are not usable on a pistol", and be willing to risk their reputations on such a frivolous charge.

Second,, the "not usable" is total BS. OK, not as easily usable as the same sight on a rifle, but so what? Just because you or I can't see that little hole at arms length doesn't mean no one can. I once had a 9mm pistol that had a fixed peep rear sight, came that way from the factory.

And, lastly, it seems you overlooked the simple fix. GI style rear leaf peep sight hole too small at arms length?? Make the hole BIGGER!

You could even just cut the top of the rear sight turning it from an "O" into a "V" or a "U" shape, which could be seen and used at arm's length.

Seems to me that would solve any potential issues, no matter what kind of ATF zealot you meet. A real zealot might still try to prosecute, but the would have to find some OTHER argument to use.

 

[Sharkbite]

The large hole on AR style rear Sights is totally useable at arms length or pushed out on a sling MP5k style.

 

[HiBC]

OK.

Y'all do whatever makes you happy.

I'm not telling anyone what they can or cannot do.

I'm telling you how I interpreted the 2017 BATF letter as I read it,and what steps I took to comply.I specifically said I'm not a lawyer or BATF agent,nor an expert. I'm finding my way through a build.

The letter did not specify features,such as sights. It specified design or redesign toward the intent to shoulder fire.

There are a whole lot of lawyers and a Supreme Court in the business of interpreting the US Constitution. Folks differ.

You are certainly free to build your AR pistol however you see fit. Its no concern of mine.

I believe there will be a few people who will read my stuff and say "Hmmm,he has a point," and reflect it in their build.

Or it might be that a top BATF agent will come on here and tell me I'm all wet,use whatever sights you want.

I accept that I might be wrong.

Its one of those "Unknown and unknowable" things when the criteria is .
intent. Time will tell.

44AMP:

You could even just cut the top of the rear sight turning it from an "O" into a "V" or a "U" shape, which could be seen and used at arm's length.

Bingo. Exactly the solution I came up with. XS sights sells a modified version of the flip aperture with the addition of an open notch on top of one aperture

I mentioned it earlier. As far as looking through the large aperture at arms length, eyes vary. You might be able to do that just fine.

My eyes,despite my will,would focus on the rear sight rather than what could be seen through that little hole.

 

[Cheapshooter]

The sighting system is completly irrelavint. There have been optics mounted on handguns for many years. I have handguns in rifle calibers like 22 Hornet, 223, 7-30 Waters, 35 Remington,all wearing optice. Plus a bi-pod. I take it you've never heard of Thompson Center Contender. I have a handgun that is intended to have optics built with no "irons" at all.Even comes with a bi-pod in the case. Ruger Charger Takedown. Semi auto, high capacity mags available intended to have optics. BATF agents aren't raiding Ruger because of it.

 

[HiBC]

Cheapshooter,

You have completely missed my point. Yes,I know handguns get equipped with optics. I have a .260 MOA Maximum handgun with a 4x Leupold handgun scope on it. I'm quite familiar. No problem.

Are your handgun scopes short eye relief rifle scopes,or longer eye relief pistol scopes?

I'll agree,the sights themselves don't matter.

The BATF letter does not talk about sights.

One more time,then I'm all in favor of closing the thread. I just don't understand the hostile environment.

If you buy an AR pistol,its (likely) BATF approved. No problem. You can incidentally put the brace against your shoulder and fire it. Legally.

What I saw in the BATF letter was vague language about "manufacture" "modify" "design or redesign" toward making a firearm "INTENDED' to be fired from the shoulder.

Just my take on it,but if I were a BATF agent, if the sighting system on an AR "pistol" has had a sight attached (thats the mod or redesign) that would ordinarily be used on a rifle ....this sight being a peep sight or short eye relief scope..
It seems pretty strong evidence the intent is to put your eyeball around 2 to 4 inches behind the sight. That might say the pistol was modified or designed to be used held as a rifle,which would make it an SBR.

I'm not trying to tell anyone else their gun is wrong.

I just decided to build my gun to have an open iron rear sight,along with the peep aperture,on the rear sight. Problem covered. When I mount a red dot,most have unlimited eye relief. No problem!! I'm confident the BATF will be happy!!

If I mount a 4.5 to 14 rifle scope on it,and I'm seen whacking away on the bench,holding the gun against my shoulder, I might be vulnerable over the "intent" thing,without saying the scope is illegal.


From the BATF:

"The receiver extension/buffer tube on an AR-type pistol serves a legitimate, vital function in the operation of the weapon system; and if utilized as originally designed is not considered to be a shoulder stock. Further, a pistol that has an AR-t1pe buffer tube or similar component assembled to it, which consequently allows for the installation of a saddle/cheek enhancement accessory, is not classified as a SBR; nor unlawful to possess.

However, if a pistol assembled with an AR-type buffer tube or similar component; which in tum, redesigns the subject AR-type pistol to be designed or redesigned and consequently intended to be fired from the shoulder; an NFA weapon as defined in 26 U.S.C. $ 58a5(a)(3); has been made."

End quote.

The BATF clearly states the difference between a legal AR pistol and a SBR is INTENT.
Sights CAN be evidence of intent. Now you do whatever makes YOU happy.

I'm done. I don't understand the negative vibes. Life is too short for this BS

I don't care.

 

[stagpanther]

Sights CAN be evidence of intent.

What?? Where do you get that from? Not trying to be hostile.

BTW--I have an AR pistol with NOTHING on the buffer tube and successfully shoot it with any kind red dot or scope--though I prefer a red dot on it.

 

[Cheapshooter]

Some of my lower powered Contender barrels do have what you are calling "rifle" scopes. Some of my rifles have "pistol" scopes.
The choice of optics has no bearing on "intent" what so ever.
BTW, my 300 BO AR pistol wears a Sig Romeo 5, and has 45° BUIS flip ups. Great combination.

 

[44 AMP]

The BATF clearly states the difference between a legal AR pistol and a SBR is INTENT.
Sights CAN be evidence of intent. Now you do whatever makes YOU happy.

I understand your concern, I just think its a bit misplaced worrying about the sights ALONE as "clear" evidence of intent.

the main "intent" of the ATF letter is about "buttstock/not a buttstock" within the existing laws, most of which are based on definitions made decades before the AR was designed.

The basis of the argument is, if something that you COULD put against your shoulder but doesn't seem "intended" to be used as such, vs something with a buttplate that clearly IS intended to be shouldered.

Be it a buffer tube or a "brace" if it has a buttplate of some kind, it is intended to be fired from the shoulder. A buttplate serves no other purpose. And if "intended" to be fired from the shoulder, then by definition it is a stock, and with a stock and a barrel less than 16" it meets the definition of a short barrel rifle. And if it is a short barrel rifle then it is an NFA weapon, and NFA rules apply.

IF you choose to assume the ATF's "intent" covers ALL parts on the gun, you may, but using that logic, you're already sunk. Take at look at your gun, its an AR pistol, right? Lower is registered as a handgun. OK. Now look at the rest of the parts, any part, and every part on the gun that is NOT "clearly" a part specifically made for the pistol is a rifle part.

If they could take you to court over "rifle" sights, they could take you to court over a "rifle" bolt, carrier, all the internal lower receiver parts, possibly even the screw that holds the pistol grip on.

Or how about the fact that it is loaded with "rifle" ammuntion???

They aren't doing that. I would be amazed if they would even try, because A) losing such a case reflects poorly on their competency. and
B) there is so much parts "commonality" between some "specialty" pistols and rifles a compelling argument cannot be made, other than the buttplate issue previously mentioned.

I would think that, in regard to "peep sights mean you intended to fire it from the shoulder" is an argument easily "shot down". There is no law or regulation requiring you to fire the gun held at full arm extension. I'd think finding someone who can demonstrate that the pistol can be held and fired without being shouldered, and close enough to use a peep sight would not be difficult.

Also remember that its not a murder case where things need to be proven beyond a reasonable doubt. If there is nothing else indicating an intent to fire from the shoulder (such as something they can claim is a stock) I think the case would be tossed out, and prosecutors, knowing the most likely result won't waste their time (and their reputation) on it.

Am not a lawyer, don't play one on tv so my advice is worth what you paid for it, but I think you're not going to get busted for "rifle sights" on a handgun.

 

[stagpanther]

Be it a buffer tube or a "brace" if it has a buttplate of some kind, it is intended to be fired from the shoulder. A buttplate serves no other purpose.

That's not true either--in fact the atf issued a "ruling interpretation" on that when the brace was first introduced.

This is one of the top dead horse champion topics, gets beaten all the time. First of all, the government has yet to hire mind-readers that can present to a court convincingly what someone was actually thinking at the time they pulled a trigger--nor have they proven that an inanimate part has a will of it's own.

Bottom line:

1. Do not press into service a registered rifle's receiver as a pistol lower.
2. Do not routinely/consistently use a set-up that otherwise is an SBR using your shoulder as an anchor point to steady the rifle for aiming and absorb recoil (I see that on YouTube).
3. If you "inadvertently" happen to contact the butt(whatever) to your shoulder--you are not going to suddenly be faced with a swat team raid and snatched into a van for a ride to the Guantanamo Bay. If you routinely use the pistol with a shoulder anchor as an SBR is intended to--then it's a question of time before either your luck runs out and the man catches you (and cares enough ) or if, like poaching, one of your neighbors calls you in.