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By Weapon
Parts shortages and shipping delays have stalled this thread much longer than planned but I can still get a solid start on it.

Most of this will apply to basically any AR setup but I will also point out some tune ups that should be left to “competition use only” and others that are more along the lines of SHTF/home defense. An AR for home/self defense? With the right ammo, yeah - it is an option but more on that later.

The general idea to keep in mind with any AR build (direct impingement or piston driven) is they are gas operated. Gas is the heart of the design and should be a major focus when you start your build or when you start tuning your factory built AR. I have seen many factory built and home built ARs that treat the gas system more like an afterthought when it should be a major focal point in the build. Just to stress the importance of the gas system, I am going to start this with two parts that will seem slightly odd...

The Barrel and Gas Block.
What? No upper receiver and lower receiver as starting point? Nope.
My starting point for an AR is always the gas system. The initial point is actually the gas block but you cannot pick the gas block without deciding what barrel you want to use because the gas block has to match the barrel diameter.

Most of us are likely using one of the standard AR profiles but it is easy to figure out if you have a pair of calipers - simply measure the diameter of the barrel near the gas port. Many government profile barrels (including SPR profile) will be .750” but if you are just ordering the barrel for the build, the specs for the barrel diameter at the gas port will always be included so you can pick your barrel and order your gas block as soon as you have chosen a barrel.

Worthy of all caps:
There are several good ones on the market - JP, Odin, Superlative Arms (my current favorite but it may not work with some really slim free float handguards), etc.

Why spend $75-$110 or more on an adjustable gas block when you can get a low profile block for $20?

Gas runs the gun and ammo shortages have resulted in manufacturers making some odd decisions to please the average gun buyer. People expect their ARs to run cheap ammo. Cheap ammo is often underpowered compared to milspec ammo and that means less gas to make the gun cycle. In order to make their ARs run cheap ammo, many manufacturers simply increased the size of the gas port in the barrel. It’s the cheap and easy fix to make an AR run under powered ammo...but it also means the gun will be overgassed with milspec ammo as well as most warmer commercial ammo.

Why is this a big deal?

Overgassed ARs have much more recoil/muzzle rise than necessary, they will wear out parts faster due to more violent cycling and they are much more apt to damage your brass if you are a reloader. None of this is good.

An adjustable gas block will allow tuning the AR to whatever ammo you are running so that it has no more recoil than necessary to run (obviously, with a slight safety margin). Other bonuses: moving parts will last longer, brass will not take as much of a beating, you can shoot faster while still maintaining accuracy and, with the right block, the AR can even run a bit cleaner and cooler.

How much less recoil? Many may find it hard to believe but an AR shooting milspec M193 or M855 can have recoil and muzzle rise that is about like a Ruger 10/22.

Coffee break...and then some pics.
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By Weapon
Two ARs on opposite ends of the spectrum:
FFD6FE07-3991-4402-AD53-3091354BE980.jpeg (223.59 KiB) Viewed 1647 times
The one in front is a fairly standard PSA PA-15 in a somewhat M4ish profile (M4gery). It has a 16” barrel with a relatively inexpensive compensator, a tuned up trigger, KNS pins, a LaRue stock, a LaRue grip and some other fairly light upgrades. It has a carbine length gas system.

The one behind it is one I put together from the ground up with a few carefully chosen parts. I generally refer to it as the “anti-AR-snob/poverty pony rifle” as it was intentionally built with many parts that AR snobs often claim cannot be used to build a solid AR.
Parts list:
Anderson upper and lower (about $80 for both at the time I bought them)
RA-140 trigger (caught on sale for ~$80)
KNS anti-rotation, anti-walk pins
18” Stoner (Midway brand) 1:7” twist Stainless SPR profile barrel (~$100 at the time)
Anderson Standard AR lower parts kit (you can often save yourself some grief if you use a parts kit made by the same manufacturer as your lower and upper)
Anderson buffer tube/receiver extension with a tuned up buffer and the inside of the tube polished up a little
Magpul enhanced trigger guard
Superlative Arms adjustable gas block (clamp on version but the set screw version works just as well)
LaRue RAT stock
LaRue Grip
Brownells Lightweight NiB bolt carrier (note: I consider lightweight carriers and lightweight buffer systems as being “competition use only” for the most part. Many manufacturers of lightweight components will tell you the same. You can use a standard M16 carrier with an adjustable gas block and get almost zero muzzle movement by gas tuning so a lightweight carrier is not needed for a defensive use AR)

SJC Titan compensator (note: if you are shooting in any particular competition division, pay close attention to its specific rules for compensators before ordering one)
UTG Pro free float handguard (they used to be fairly inexpensive but not so much anymore)
Rifle length gas system
And a few other minor this and that parts (eg quick adjust, QD sling I made, etc)

I kept the 16” PSA almost stock for comparison purposes. The 18” AR briefly ran a standard A2 flash hider and a standard gas block for baseline testing. With the standard gas block, the 18” AR was a bit softer shooting than the 16” due to the difference in gas system lengths. Carbine length gas systems are much shorter and can be somewhat nasty to tune up. ARs with mid-length or rifle length gas systems are typically much easier to line out.

In short, the difference in their recoil, muzzle rise, recoil impulse and overall cycling is now shocking to the point that is it hard to believe they are both ARs when running the same ammo. The 16” almost stock PSA feels very much like an AKM where the 18” AR feels like it is shooting .22 target ammo. While some of the difference is from the longer gas system length and the more effective compensator, it is the tuned up gas system on the 18” rifle that is making most of the difference.

How to spot an overgassed AR:
The ejection pattern is the easiest test to get an idea of how dialed in your gas system is to your ammo.
Simply stand in one spot, fire off about ten rounds and pay attention to where the brass is going. The best method is to have a second person watch the brass ejection pattern or to video it but can get a fairly good idea just by tracking down your brass after ten rounds.
If you consider the target downrange to be 12 o’clock, and directly to your right side as 3 o’clock, brass ejection between 12 and 3 is a strong indicator of overgassing. Another really strong indicator is badly dinged brass.
A properly dialed in 16” AR will eject brass at around 4 o’clock and the brass will typically be undamaged with no noticeable dents or dings.
A 20” rifle with a rifle length gas system will typically eject brass between 3:30 and 4 o’clock but I wouldn’t be too worried about one ejecting brass at 3 o’clock unless the brass was getting dinged up.

Since I mentioned comp restrictions, USPSA tactical and limited comp rule - maximum is 1” (diameter) x 3” (length) when measure like so:
EF94E4FC-DC87-4B3A-A26F-4C2AAE3AF564.jpeg (114.1 KiB) Viewed 1304 times
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By Weapon
LT USN (Ret.) wrote: Sun Jul 26, 2020 1:45 pm Good Stuff!

Will this thread go to AR9 variants or stick with .223/5.56?
Most will be on direct impingement 5.56 AR builds but i may throw in some PCC stuff. Hmm. Maybe a PCC thread as well after I finish this one. I have noticed a lot of people having problems with AR9 builds lately and I tracked down the source of the problem with many of them not long ago.
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By Weapon
Barrel profiles, twist rates and gas system length.

Obviously, any AR setup is going to depend its particular purpose - do you want a competition gun? A SHTF gun? A General use range toy?

For general use and possibly SHTF, an 18” AR with an SPR profile barrel, 1:8” twist, and rifle length gas system is hard to beat. It isn’t as clumsy as a 20” barrel but has a little more range than a 16” or shorter barrel. While the SPR profile does add a bit more weight to lug around, it doesn’t heat up as quickly as thinner barrels and is capable of producing consistent 5-shot groups from a bench if you want to punch holes in paper.

When paired with a collapsible stock and carbine buffer system, an 18” AR is also still fairly easy to transport. The collapsible stock also makes it easy for most people to get the length of pull they need for the rifle to fit them. Really tall folks might need something a bit longer but I am 6’4” and the LaRue collapsible stock is extremely comfortable for me.

Gas system length:
Unless you have to go with a pistol or carbine length gas system due to a barrel under 16”, get a barrel setup for a mid length or rifle length gas system when building or buying one in .223/5.56. It will save you some tuning headaches.

16” barrels are usually easy to find set up for mid length gas but you can also find a few which have rifle length gas port placement. Many will also have carbine length port placement so you have to pay close attention to the stated specs when you are buying any 16” AR barrel.

18” barrels usually have rifle length gas port placement but you sometimes come across an odd one with something else so it is always a good idea to double check the port placement before clicking the “submit order” button.

.223/5.56 Chamber options: .223rem, .223 Wylde, 5.56NATO

.223 Wylde is my go to for all around use. For those who have never heard of it, it is a hybrid chambering that works very well with either commercial .223 Remington ammo or milspec 5.56NATO ammo. My second option is a 5.56NATO chamber. Not long ago, I would have said “definitely get a .223 Wylde unless you plan on shooting only 5.56nato ammo” but in the current pandemic buying panic, sometimes you have to go with whatever you can find in stock.

Barrel twist rate.
I will skip the full explanation of twist rate but the most common in ARs are now certainly 1:9”, 1:8” and 1:7” (milspec for the M4).
Many people leap to the conclusion that 1:7” must be the best because that’s what the military uses, however, that choice had a really odd basis - they didn’t want to have to change their 5.56 tracer ammo so they picked a twist rate which was slightly less accurate with the standard issue ammunition at the time.
1:7” twist barrels are often the best choice only if you plan to shoot ammo that uses a 69gr (or heavier) projectile. Most fairly inexpensive ammo is 55gr or 62gr.

As such, for a general use rifle setup to run the most readily available inexpensive ammo, 1:8” or 1:9” twist are likely better options than 1:7.

Yeah - most of this has been intro material up to this point but it may save someone from buying an AR that will end up being a pain to tune up. :)
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By Weapon
Side note: my apologies if these are somewhat riddled with typos - I just switched phones and the keyboard spacing on this one is different than my last one. Yes - I often type these crazy long threads on a phone while I am snapping pictures, editing photos and working on gun mods at the same time. As such, they tend to be a coffee-driven, typo-riddled, somewhat disorganized, info-blurt at first. :?
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By Weapon
A few more notes for people considering a first-time AR build.

There are some parts that simply will not work with others and it often isn’t readily apparent when you are picking parts. Also, while ARs are very modular, some manufacturers love to try to reinvent the wheel and their parts may have proprietary components that require unusual or special tools.

MLoK Free float handguards for ARs are all the current rage but there are definitely some headaches that can pop up with them. As such, before you order any AR handguard there are a few points that are worthy of attention.

The first is the type of barrel nut used and whether it requires any particular tool for installation. If the parts website selling the part has a review section, you can do yourself a disservice by not taking the time to read the reviews. Many people will be nice enough to layout any issues they had during installation.

I have had several handguards with barrel nuts that require tools which are hard to find, unusually expensive or both. Look through the specs and make sure you know what tool is required and, if it is some bizarre proprietary wrench, is the damn thing included? Example: a 1.2” or 30.6mm thin crowsfoot wrench...yeah, good luck finding that locally on short notice :shock:. Getting all the way to barrel installation only to have to put your build on hold to track down and order some weird barrel nut tool is frustrating to say the least.

The second potential headache with handguards is the internal diameter. Really slim, long handguards are very popular at the moment but you have to pay close attention to the internal diameter for any handguard that will extend beyond the gas block. Many of the really slim handguards will have an internal diameter that is as small as 1.3” and they will not work with many of the better adjustable gas blocks (especially the clamp-on type gas blocks which have a little more material above and below the barrel).

1. Order a handguard that stops before the gas block. Cons: Doesn’t look as cool, doesn’t allow optimal support hand placement, may leave part of the gas tube exposed and subject to impact damage.
2. Order a larger diameter handguard. Cons: may not be quite as comfy to grip.
3. Use a standard, non-adjustable low profile gas block. Pros: easy and inexpensive. Cons: no tuning if you end up with a severely overgassed AR...and you will likely end up with an overgassed AR.

Lower parts kits.
As mentioned previously, you can usually avoid some headaches by going with a lower parts kit made by the same company that made your lower receiver. You would think that any milspec parts kits would work and they usually do, however, they will often be a considerably different color and, occasionally, some parts just flat out will not work. I recently had a higher end parts kit that included a mag catch that just would not work with a particular lower. Both parts were made by great companies that keep things in spec but those two parts just would not play well with one another.

Keep your intended use in mind when ordering your trigger components. While a standard milspec trigger group may be very durable, they also often end up having a trigger pull that feels like you are dragging an 8 foot logging chain over a gravel road. You can find lower parts kits that include everything but the fire control group. I try to use them whenever I can find them in stock as that milspec trigger group will almost always end up in a spare parts box anyway.

There are now more drop-in triggers on the market than ever so you can basically find whatever trigger pull weight you want with either a single stage or two stage trigger. You can also spend almost as much on the trigger as every other part needed to build an AR...but this will get to some more budget friendly options including how to improve the stock trigger if you are stuck with it due to budget. $10-$20 can go a long way towards making a stock trigger decent.

Final note on drop-in triggers: many of them require or at least work better with antiwalk pins. Regardless of the trigger you are planning to buy, check the specs to see if the trigger requires special pins and, if so, if they are included or If you have to buy them separately.

Trigger guard installation.
Almost forgot to add this one. A trigger guard should be easy to install on an AR, right? There is a problem that many people do not catch with the rear roll pin. You will occasionally get a pin that is a little too large or a pin hole that is a little too small. If you have to tap it in with too much force, you can break one of the ears off the lower receiver. That situation sucks (luckily, I have never had it happen to me but I have seen it happen to quite a few others).
Solution 1: get a support block, lightly lube the pin and be very careful tapping it in.
Solution 2: get a trigger guard pin pusher. Yeah, they actually make a tool to install this one specific pin in an AR
Solution 3: my go to solution for this possible problem - Gen 2 Spikes trigger guard: ... ii-sla0102
The Spikes trigger guard doesn’t require any hammering. Just take a small punch and push in the pin. It has a spring loaded detent to keep the pin in place once installed. Bonus: extra room if you are wearing gloves, looks great.

Muzzle brakes/flashhiders/compensators:
I try to avoid any which have really sharp edges on the front. This often includes several brakes designed to look intimidating and some types of open prong flash hiders (not all of them as some companies are nice enough to radius/deburr the edges very well). Why? Ever go out to shoot in 104° heat wearing shorts and then do a rapid rifle to pistol transition? That liquid running down your leg afterwards is probably blood. Also, when you are running and gunning and trying to move as quickly as possible around obstacles, sooner or later, you will take a dive. Almost every competition shooter I know has had a wipe out. My last one was at full throttle. X_X Landing on a fanged/spiked muzzle brake or flash hider could end very badly.


My friend, you do such a great service to this forum, you’re spelling, syntax, whatever wouldn’t matter. We’re just all the smarter and more educated because of you.
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By Weapon
LT USN (Ret.) wrote: Sun Jul 26, 2020 5:06 pm
Weapon wrote: Sun Jul 26, 2020 4:54 pm you want with either a single stage or two stage trigger
Opinions on single-stage vs. two-stage? Does it really just come down to personal preference?
There is definitely some personal preference involved but the type of shooting is a huge factor.

If you are talking about long range precision shooting with an AR-15 or AR-10, almost all of the pro guys are using an adjustable two-stage trigger.

On the other hand, most run and gun triggers are either hybrid or single stage with lots of focus on really quick trigger reset. Hybrid triggers are slightly odd and about the only way I can think of to describe them is a really smooth rolling break where the typical single stage trigger (really great ones - not milspec) has a very minimal amount of creep and then a clean break. As usual, most of these triggers are lighter than typical pull weight - often around 3lbs.

Tactical/self defense/SHTF ARs are almost always setup with a single stage trigger but with a bit more creep and definitely heavier pull weights. 5.0lbs to 5.5lb pull helps account for the effects of an adrenaline rush on fine motor functioning and also other factors (like if you have to wear gloves). A Light single stage trigger + gloves + adrenaline = oopsie bang.
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By Weapon
Time to get to the tools...

Whether you are building an AR from a bunch of parts or you are upgrading an existing AR, as with almost any other gun, there are a few specialized tools that are must have items, a few that are really nice to have and quite a few that you can skimp on if you plan to only build a few (warning: they tend to multiply - left over AR parts somehow end up turning into extra, some good tools may be worth the effort).

If you plan to build several ARs and you have an extra $240 in your pocket, Real Avid makes an AR Armorer’s Master Kit that includes just about everything you will need for any AR build including bench blocks, vise blocks for the upper and lower, torque wrench, the correct punches, etc. It is a really nice kit’s also $240.00.

If you want a less expensive approach...
Wheeler Engineering has a basic AR-15 wrench/combo tool in their Delta series that is around $30. It has a number of AR specific uses and it can also be attached to a torque wrench. One side of it is a milspec barrel wrench, the other is a castle nut/buffer tube nut wrench. It works but the barrel wrench end is far heavier than the castle nut wrench end and it makes it very unbalanced when you are tightening a castle nut. Still, If you have a milspec build or have to work on one, it is worth the $.

Torque wrench - some people claim they are absolutely essential but I wouldn’t go quite that far. The barrel nut torque specs for many barrel nuts is 30ft lbs to 80ft lbs but I always try to stay on the low side between 30ft-lbs to 45ft-lbs or torque. Some manufacturers will actually tell you to avoid exceeding 45ft lbs with their barrel nuts - Aero is one of them if I recall correctly.

If you have a barrel nut with a range of only 15ft lbs of torque or one that specifies a specific number (like exactly 35ft lbs of torque), a torque wrench is a good idea - Harbor Freight has a fairly inexpensive 1/2” drive 30-150ft lb torque wrench that works for only $20: ... 63882.html

Upper receiver vice block - sorry but it is just about a must-have item. Wheeler makes a fairly cheap one that works well enough and also comes with a gas tube alignment tool:

A Hammer or snooty gunsmith hammer

Gotta have them:
Standard pin punches: 3/32”, 1/8”, 5/32” (amazon cheapies will work)
Roll pin punches: 1/16”, 5/64”, 1/8” (amazon cheapies will work)

If you want a nice hammer and punch set that includes some optional extras that will certainly make life easier, track down the Real Avid Accu-Punch Hammer & AR-15 Pin Punch Set AVHPS-AR. The starter punches in that set will keep your blood pressure in the safe zone when dealing with smaller pins.

One extra tool that is very nice to have is the Real Avid pivot pin tool. It makes it really easy to install the detent for the pivot pin. You can install that part without this tool but you may run out of profanities before you get that little sucker installed:

Optional: dremel and felt polishing wheels

The usual supplies:
Milspec gun grease
Some 800, 1000 and 1500 grit 3M paper
Tetra gun grease
Paper towels, rags, q-tips
Gun solvent
Your favorite gun oil
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By Weapon
If you have an AR with an A2 type front sight base (i.e. like the front sight on military M4s and M16s) there are three more things which are highly recommended if you ever want take off the front sight base:
This punch: ... 26485.aspx

This bench block: ... 20727.aspx

And around a 4-5lb hammer.

This may not apply to all brands but it is certainly true of many — the pins in that front sight base can be incredibly hard to get out. Unfortunately, if you want to change an AR over to a free float handguard from a milspec barrel nut and handguard, that sight has to come off.

How well are the taper pins smacked in there? I have had to use a press on one sight base, the rest often required a 4lb hammer. They can try your patience and your hammer swinging arm.
I'm a big fan of the Real Avid stuff. Well thought out and good quality for a decent price.

One thing on the punches, to me roll pin starter punches are a must. Can you get away without them? Sure. But they will pay for themselves in the first build where you are building from scratch. They will save you time and frustration and flared pins.

Also, I will respectively disagree and say to get a "good" set of punches. I started with cheap punches and starter punches and many of them bent or didn't hold the pins well. It's worth spend a few extra bucks for a quality set from an firearm oriented company. I eventually bought "better" punches from Brownells and never had a problem. One of my cheapo punches that bent on the first try now has a place removing the pin on the safety of my SAR9 as it bent perfectly to allow easily removal of that pin.

Also, not sure if you mentioned it (still reading through) but before you build your first AR, get some extra springs and detents for the pivot and takedown pins. You WILL lose one at some point so have extras on hand. You can get plenty on ebay for a few bucks.
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By Weapon
Oh yeah - if you plan to work on lots of guns, definitely get some good punches right off the bat. That Real Avid Hammer and MSR pin kit is only $31 on amazon and worth every penny. I have gotten fairly lucky with the cheap punches I have ordered from amazon but I often use them to make specialized punches in the end for something similar to your sar9 safety punch. I have several that I have bent and then torched for a second to lock them in that position. :)

An AR “easily lost pin and spring” replacement kit is always a good Idea - there are several companies who offer good ones for cheap. I occasionally cram one of those in AR grips if they have a compartment...and that reminded me of two tools I failed to mention. Time for the edit button.
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By Weapon
I planned to add more to this tonight but a 15 hour day with 9+ hours in court would lead to an unintelligible, dumpster fire post...possibly even with blurry pics. So, it will resume after tomorrow morning’s coffee. :)
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By Weapon
Fixing some common problems...

You can avoid a lot of these by jumping up a notch or two in price range...or you can use some elbow grease and save some money. Of course, if you are in the middle of a buying panic, you may not have much choice other than to use whatever you can find.

If your AR feels rough and makes a lot of noise when you pull the charging handle (zrrrrrp!), it is often a result of the machining inside the upper receiver and/or the buffer tube. Not long after Sandy Hook, when the buying panic was in full force and manufacturers were struggling to meet demand, quality dropped with many manufacturers and you would run into things like:

Not so great machining in the upper receiver - note the almost zipper like ridges....zrrrrrp!:
23461B74-2F5F-4CC9-8830-09F8F45F5776.jpeg (257.8 KiB) Viewed 1508 times
Same upper from a different angle:
6099C6D9-F622-4401-8A59-84195C3143A8.jpeg (154.51 KiB) Viewed 1508 times
A buffer tube with a similar problem:
66BBF77D-2A7B-4458-990F-FCEB308BDBC3.jpeg (119.97 KiB) Viewed 1508 times
Those are some fairly nasty machine marks. You could hear and feel them whenever the gun cycled.
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By Weapon
For a nasty buffer tube, the easiest fix is 3M wet/dry paper. For really bad ones, I start with 400grit and then 600, 800 and 1000. You just have to roll up a piece and move it in and out of the tube to knock down the ridges and then clean all the dust out afterwards:
E2A3FBE4-D5B8-4B29-A175-175D549A5738.jpeg (285.02 KiB) Viewed 1508 times
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By Weapon
Smoothing out machine marks like those shown above isn’t just about making the rifle feel better - smoother cycling reduces the odds of a hangup so it is worth the effort to clean up.

If you already have your buffer tube off, you might as well inspect the buffer spring as well. I often polish the buffer spring to make them run more smoothly. It is a bit of a task and if I didn’t have a bench polisher I would probably just order an AR15 spring from Sprinco or JP.
Another trick that can make them a little smoother when they are brand new is to pull out the buffer spring and give it a light shot of spray on white lithium grease (auto parts store). After break-in, I clean out the grease as it tends to turn into a glue like goop after several weeks. Luckily, the buffer and buffer spring come out very easily and a 12gauge mop is just about the perfect size to clean out the buffer tube.

Pic of the build I am working on at the moment. The stock is on backorder so it is wearing a standard milspec stock for the moment...with the current prices in the AR market, the upper, lower and trigger cost more that some complete ARs I have built in the past:
74513B00-3D7F-4531-8F63-41F6A32C8589.jpeg (188.82 KiB) Viewed 1498 times
I too have had a hard time rounding up my stock of choice recently. VLTOR’s IMOD seems to be in the same place as UNOBTAINIUM as is Young’s National Match BCG. Got most of the parts for a reasonably nice 300 Blackout in the mail but these pieces mentioned have eluded me to this point.

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