Weaponizing the AR15

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Re: Weaponizing the AR15

Post by Weapon » Tue Jul 28, 2020 7:18 pm

GearHead_1 wrote:
Tue Jul 28, 2020 7:07 pm
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.
Yeah - there is quite a bit of stuff right now that is just sold out everywhere with no ETA. Between covid-19 and the riots, AR15s and AKMs became the new toilet paper and bottled water.
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Re: Weaponizing the AR15

Post by GearHead_1 » Tue Jul 28, 2020 8:07 pm

Poly80/Glock pistol pieces have also become increasingly more difficult as well. I’ve watched the price of quality slides and barrels creep up and just keep on creeping. It’s interesting to me how during the COVID deal I have much more available time and the things I’d like to use to fill that time are making it so that I can’t easily do it.
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Re: Weaponizing the AR15

Post by Weapon » Tue Jul 28, 2020 9:08 pm

GearHead_1 wrote:
Tue Jul 28, 2020 8:07 pm
Poly80/Glock pistol pieces have also become increasingly more difficult as well. I’ve watched the price of quality slides and barrels creep up and just keep on creeping. It’s interesting to me how during the COVID deal I have much more available time and the things I’d like to use to fill that time are making it so that I can’t easily do it.

Yeah - SHTF and everyone was suddenly pro Second Amendment. I haven’t heard “you don’t need that for hunting!” since February 28th. :lol:
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Re: Weaponizing the AR15

Post by ncjw » Wed Jul 29, 2020 8:47 am

Weapon wrote:
Tue Jul 28, 2020 9:08 pm
GearHead_1 wrote:
Tue Jul 28, 2020 8:07 pm
Poly80/Glock pistol pieces have also become increasingly more difficult as well. I’ve watched the price of quality slides and barrels creep up and just keep on creeping. It’s interesting to me how during the COVID deal I have much more available time and the things I’d like to use to fill that time are making it so that I can’t easily do it.
Yeah - SHTF and everyone was suddenly pro Second Amendment. I haven’t heard “you don’t need that for hunting!” since February 28th. :lol:
Exactly!

(BTW, I never expected that a major political party would endorse (by inaction and lack of criticism) anarchy and wholesale crime, looting and murder. The old saying goes, "the first one to mention Hitler loses the argument", but study your 1933 German history, it is the same playbook.)
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Re: Weaponizing the AR15

Post by Lgaam » Wed Jul 29, 2020 9:10 am

ncjw wrote:
Wed Jul 29, 2020 8:47 am


Exactly!

(BTW, I never expected that a major political party would endorse (by inaction and lack of criticism) anarchy and wholesale crime, looting and murder. The old saying goes, "the first one to mention Hitler loses the argument", but study your 1933 German history, it is the same playbook.)
Godwin's Rule died the night Hillary lost; particularly for folks with a left-of-center lean. I'm dealing with "othering" just within the extended family circle.
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Re: Weaponizing the AR15

Post by Weapon » Thu Jul 30, 2020 9:41 am

Back to some tuneups...
If you get or have an upper receiver that looks like this (i.e. fairly rough machine marks):
794B0F4E-0218-4BDF-9F56-EA9024575612.jpeg
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You can smooth it up quite a bit by very lightly polishing the contact points for the rails on the bolt carrier group with 3M paper. The points that need cleanup are easy to spot after the bolt has been cycled some or certainly after live fire. They will show up as slightly shiny straight lines that correspond to the rail positions on the BCG.

The rails on the BCG also often need some clean up as they often have some minor burrs or a rough finish on the contact points. The rails are in the same position on both sides of the BCG:
D2C8284F-331D-4961-AF68-655FAAE35391.jpeg
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And
28D05D28-5168-4803-80FB-93CCE3143DBB.jpeg
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You certainly don’t want to take too much material off of the rails so either a very fine grit 3m paper (1000) or a Dremel with a felt wheel and a polishing compound like Flitz or Maas is usually the best way to go. Once they have been cleaned up, I usually add a very thin coat of Tetra Gun grease to those contact points before reassembling the rifle.
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Re: Weaponizing the AR15

Post by Weapon » Thu Jul 30, 2020 10:16 am

Speaking of bolt carrier groups, for a competition AR, a lightweight bolt carrier is a great upgrade. A typical milspec BGC is about 11.6oz which is quite a bit of reciprocating weight. You can find lightweight carriers that are anywhere from around 5.8oz up to 9.5oz. The lightest often lose forward assist functionality but you can find ones which still have the FA grooves in the 8oz range.
Lightweight NiB BCG:
6BD5BF4F-0427-4CC1-86F4-C58101675012.jpeg
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That one in the pic is ~3.4oz lighter than a milspec BCG but still has the FA grooves.

NiB is nickel boron plating. It is very slick and makes the BCG a bit easier to keep clean as carbon doesn’t stick to it as well. If it has quality NiB plating, it’s a nice upgrade. I have seen some who tried ultra-inexpensive NiB BGCs have issues with the finish flaking as the parts were apparently not properly prepped before plating. This is another time when doing a google search for part reviews can pay off before you start clicking the order button.
Side note: many people say you don’t have to lube NiB or TiN (titanium nitride) plated BCGs. I lube them exactly the same as I would with any other BCG. If they run great without lube, they will run even better with lube.

The lightest BCGs on the market are also typically the most expensive (of course). JP’s ULMOS 7075 aluminum BCGs had an MSRP over $450 the last time I looked - they are the lightest at under 6oz and should be considered competition use only. They require tons of lubrication. At one point, the instructions for the JP aluminum BCG said something along the lines of “if your shooting glasses are not getting sprayed with lube, add more oil” :lol:

Link to JP’s lightweight carriers:
https://jprifles.com/1.4.7_LMOS.php

Some of the slightly lighter BCG’s may be almost as durable as a milspec BCG but I would certainly save all of the extremely cut down designs (especially aluminum ones) for competition ARs or range toy rifles. They are much like radically lightened slides on USPSA limited and open class pistols - sooner or later they will crack and break apart. That isn’t a situation you can solve with a “tap, rack and bang”.

So, for a defensive use or SHTF AR build, I’d be very tempted to stick with a milspec BCG or something very close to it - maybe a NiB coated yet otherwise milspec BCG.

If you want to drop $300 on a titanium BCG, you can get a light and durable BCG which could work for defensive use. Make sure it has a finish like ionbond, NiB or TiN as straight titanium will gall without some type of surface hardening. Caveat: it’s +$200 over the cost of a milspec BCG to save 3.5-3.8oz. Whether or not that is worth it will depend on your budget.

As an additional consideration, less weight in the BCG may hinder reliability in some situations even with proper tuning (extreme temps, dirty/grimy gun, etc.) This is why you will still see many people recommending milspec full-auto BCGs - they don’t make your gun full auto but they do weigh more because of the extra lug on the back of the bolt carrier.

BCG finishes...
This used to be an easy decision as almost all of them were phosphate finished but now there are at least a half dozen finish options.
Phosphate: it has served the military fairly well for decades. It’s inexpensive and has fairly good corrosion protection. However, it is also kind of a rough finish which requires more lube and is harder to keep clean. The cost of a phosphate BCGs varies wildly depending on the exact steel used, how they are tested and what company’s name is on the box. The price range is $89 to at least $170ish.

Black Nitride - a definite step up in BCG finishes in terms of corrosion resistance and lubricity. Black nitride is very slick and it makes bolt cleaning much easier. Black Nitrided BCGs typically run in the $140-$160 range.

Nickel boron - also a step up from phosphate when it comes to durability, ease of cleaning and corrosion resistance. These used to be fairly expensive but as more companies have offered this finish, NiB BCGs have dropped in price with at least a few hovering around the $100 mark.

Titanium Nitride (several different colors available) - it’s very hard and very slick. It is great on surfaces that just rub against one another but often has issues with impact surfaces over time. It is typically more expensive but there are some on the market as low as $140ish. If you just have to have a gold BCG...

Ionbond DLC (diamond-like carbon) great finish overall in terms of corrosion resistance, durability and lubricity...but it tends to drive up the cost some. I have seen some advertised for less but the only ones that I can ever find in stock are $135 at the lowest up to around $170

Prices on BCGs vary due to a number of factors so if you see one with DLC that looks like a steal, double check the rest of the specs on the BCG...
Is the bolt made of at least Carpenter 158 (milspec) steel? (9310 is an upgrade)
Is the bolt carrier made out of at least 8620? Note: there are several grades of 8620 steel and they are not all the same - basic 8620 or aircraft grade 8620? Many BCGs will not specify which grade...
Shot Peened Bolt?
High pressure tested?
Magnetic-particle inspected?
Grade 8 fasteners on the gas key?
Gas key properly staked?
Is the firing pin made out of Velveeta cheese?

A shady company could add DLC and skimp on all sorts of other stuff to make a BCG look like a deal. So, if it looks too good to be true, double check all the specs and definitely read the reviews.
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Gas System and buffer weights

Post by Weapon » Thu Jul 30, 2020 11:48 am

It occurred to me that I have just scratched the surface of AR tuning and the things you have to balance out so I will dig a little deeper into that...

Cycling of an AR is three pronged:
1. Gas (port size and gas system length - if you want to get really picky, you could also throw compensators in here as they use gas to effect felt recoil and muzzle rise)
2. Mass (weight of the BCG, buffer and spring)
3. Resistance (bit of friction, a small amount of resistance from the hammer spring and then the majority of the resistance from the buffer spring)

Other than the gas system length (unless you want to swap out barrels and gas tubes), all of the above can be tuned up. To some degree, you can control how long the bolt stays locked up, cyclic rate, bolt speed, recoil impulse, reciprocating weight and muzzle rise/dip.

As a general rule of thumb, more mass amounts to slower cycling and more felt recoil due to higher reciprocating weight. Higher reciprocating weight also amounts to more muzzle movement as you have more weight slamming back and forth in the rifle.

Okay, so why do people often use a heavier buffer in ARs with a carbine length gas system? It is often an easy fix to keep the bolt locked up a little longer in overgassed/undersprung ARs. ARs with carbine length gas systems and 16” barrels often have problems with early unlocking and prolonged dwell times so adding mass to the buffer by swapping to an H1, H2 or H3 buffer keeps the bolt locked up a little longer. More mass = bolt moves back slower so it can fix early unlocking.

The problem with this is by increasing the mass of the buffer to avoid early unlocking (due to overgassing) you have also increased reciprocating weight which increases felt recoil, causes more muzzle movement which slows follow up shot speed and it can even lead to short stroking if you use too heavy of a buffer.

IMHO, the best way to fix an overgassed carbine is an adjustable gas block or possibly an adjustable gas key but if you get a heavier buffer that is just the right weight, it can solve a number of issues. If your brass ejection pattern is between 12 and 3 o’clock and you don’t have an extra $100 in the budget for an adjustable gas block, a slightly heavier buffer or extra power buffer spring may at least save your brass and reduce wear and tear on some parts.

This will sound like a contradiction to my above statement regarding lower mass amounting to less felt recoil but how recoil feels is very subjective and, if you get the right heavy buffer, it can make the recoil feel less violent. How so? The heavier buffer will keep the bolt from unlocking early and dwell time will increase. With the right heavy buffer, the bolt will unlock after the gas in the system has stabilized and it can make the recoil feel softer. The problem is you have to try several buffer weights unless you just happened to have everything from H1-H3 on hand...or you have a set of tungsten buffer weights to play around with...purTungsten was nice enough to make a set of three tungsten buffer weights available for <$25:
https://pur-tungsten.com/product/tungst ... r-weights/
Replace one steel weight in your buffer with a tungsten weight and you have an H1, replace two and it’s an H2 and so on. If you happen to have several buffers that need to be bumped up to H1, you can convert three to H1 for next to dirt cheap instead of buying three new H1 buffers...

Remember when I said to avoid carbine length gas systems if possible? They are violent little buggers that can require lots of tuning.

Since I already mentioned heavier buffers, I will add lighter buffers to this post as well...these are competition use:
If you have a standard Carbine buffet and you want to make it lighter, there are several options. I know at least a few competition shooters who run an entirely empty buffer but most have at least a little bit of weight in there. If you need to play around with tuning a lightweight buffer for your match gun, you can get solid aluminum buffer weights and replace one steel buffer weight at a time until you get the cycling and feel you want.

KAK industries has .22oz solid aluminum buffer weights for $1 each:
https://www.kakindustry.com/ar-15-parts ... t-aluminum

White Label Armory also has .22oz aluminum buffer weights for 75 cents each:
https://whitelabelarmory.com/product/ar ... -aluminum/
I have to give some points to White Label Armory - no BS covid-19 excuses from them for shipping times. I ordered some parts over the weekend and they shipped on Monday morning.

If you go with an insanely light BCG, you may need to reduce the weight of the buffer spring as well as the weight of the buffer. Sprinco’s yellow buffer spring is a 20%RP spring and it is good for light match loads.

Some quick USPSA match load math: Everyone shooting a .223/5.56 AR15 in multigun is shooting minor power factor. Major power factor for rifles is 320 so unless you have a top secret 55gr load that hits at least 5819fps...you are shooting minor. Minor power factor for rifles is 150. As such, you can run a 55gr bullet at 2728fps and make minor...add in the usual margin for error and the lowest “safe” load is likely around 2820fps with a 55gr projectile (i.e. much slower than a typical 55gr M193 out of an 18” barrel).

However, you will find lots of guys running a lighter bullet with more zip to it as they want the extra gas to run their comps in open division. As such, a 50gr at 3100fps or faster is fairly common.
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Re: Weaponizing the AR15

Post by Weapon » Thu Jul 30, 2020 12:22 pm

Other notes on gas tuning.

Most manufacturers of lightweight bolt carriers recommend an adjustable gas system to ensure proper functioning but there are some BCGs that also let you tune the gas on the BCG side.

Example: RCA’s Ultralight Titanium BCG with adjustable gas key:
https://rubbercityarmory.com/product/ti ... e-gas-key/

Pros: adjustable gas key, very light (5.9oz), very cool, high quality.
Cons: expensive ($390ish) and not the easiest to setup (straight from RCA’s page on this BCG:
“ **THIS IS NOT AN ENTRY LEVEL BCG – TUNING YOUR RIFLE IS REQUIRED IN ORDER TO UTILIZE THIS GROUP TO IT’S FULL POTENTIAL. DO NOT PURCHASE FOR YOUR FIRST AR BUILD.”

An adjustable gas block is a much less expensive option for gas system tuning for most builds but the adjustable gas key BCGs are available if you have spare cash and spare time to set them up correctly.

Edit - I had almost forgotten about these....
If you have an AR with a milspec A2 front sight (or possibly a really slim handguard that doesn’t have room for an adjustable block) and you want adjustable gas without having to shell out $140 or more for an A2 sight with an adjustable gas system, you can upgrade the gas key on your BCG to an adjustable gas key. Swapping out gas keys can be a bit of a pain as you have to stake it on very well and assuming your original gas key was properly staked, getting it off will take some effort...still, adjustable gas for $50 or often as low as $40 if you shop around:
https://rubbercityarmory.com/product/rc ... e-gas-key/
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Re: Weaponizing the AR15

Post by Weapon » Thu Jul 30, 2020 12:43 pm

Tuning a competition AR’s gas system is a little different than that for a SHTF/defensive AR.

For a competition gun, you load one round into the mag and then fire the one round to see if it locks back on an empty mag. Then you rinse and repeat after restricting the gas until the rifle will not lock back on empty. Once you are at that point, you typically want to adjust the block back 3-4 clicks (depending on the block) to add enough gas to get lockback as well as a slight margin for ammo variation and carbon build up. The idea is to get the lowest amount of recoil while still maintaining 100% reliability with your match ammo.

SHTF/defensive use: you can tune the gas system pretty much as above but it is a better idea to tune it to the weakest ammo you have and in the coldest conditions you plan to use it if you want to have 100% reliability under all circumstances. Picking a lube that doesn’t turn to glue in cold weather can also definitely help with this. It is one of the reasons many people lube ARs with 5w-20 or 5w-30 pure synthetic engine oil..
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Re: Weaponizing the AR15

Post by Weapon » Thu Jul 30, 2020 3:23 pm

Updated the section on bolt carriers to cover more finish options as well as adding a few notes about weight vs overall reliability. Some typos also fixed...there were only about a thousand. :lol:
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Getting what you want on a budget...

Post by Weapon » Thu Jul 30, 2020 6:37 pm

This post will end up being edited with more material added as I go back through all of my AR mods looking for budget fixes to annoying problems.

The first one - if you have a milspec Collapsible stock that you are happy with but want a QD mounting socket, Impact Weapon Components has a fix for that:
08C5AA66-9DA6-45ED-BC1C-6C4A11279F2C.jpeg
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You simply locate a point on the stock with enough clearance around it, drill a hole per the included instructions and then install the retention ring on the back side:
546B3127-B0D1-4894-8DEF-638F495498BC.jpeg
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A QD swivel (at least the ones I have) will only lock in from one side of the socket but it is an inexpensive fix that works on any M4 milspec stock if you just need a QD mounting point.

A $10 upgrade for milspec triggers...
Milspec triggers are often fairly nasty with lots of grit and creep. You can polish them up but only a little as they are surface hardened and, if you cut through that hard outer layer, they will not last long.

Luckily, there is a really inexpensive fix for much of the creep from Joe Bob Outfitters so long as your AR’s lower has a fully threaded (all the way through) hole for your grip screw (most lowers do but it is worth checking before ordering). This trigger adjuster is basically a grip screw with a smaller set screw inside of it. It allows adjustment of the trigger movement and can work wonders on a milspec trigger:
D8EC7FDB-B0E1-48EB-AEA8-DACBEA95F1B6.jpeg
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If you add a JP yellow reduced power trigger spring and the JP red heavy hammer spring (JP's enhanced trigger kit $15-$20), you can turn a horrible 6.5lb+ milspec trigger into a pretty damn good 4-4.5lb AR trigger for about $30. A little very light polishing on the trigger and hammer contact points can make it even better. :)
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Re: Weaponizing the AR15

Post by Weapon » Fri Jul 31, 2020 12:05 am

Okay - you guys are hard to impress this week - tough crowd. :shock:

Imma have to up my game...
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Re: Weaponizing the AR15

Post by TL1000RSquid » Fri Jul 31, 2020 5:18 am

Nice lots of good info. I've built a bunch of AR's and they're all general purpose so for the most part I go for mostly milspec except the triggers, BCG's are all mostly NiB from AiM and Toolcraft, Radian CH's, adjustable gas block's. I've also 2 precision builds one 5.56 and a .308 which i plan to dump and build a 6.5 upper.
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Re: Weaponizing the AR15

Post by LT USN (Ret.) » Fri Jul 31, 2020 6:40 am

Good stuff. I had already smoothed out the buffer tube from some other thread you mentioned it in. It really did help.

Plus, from an earlier thread on lubes, I use the synthetic oil 5w-30 and Mystery Oil combo recipe you recommended for most of my firearms.
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Re: Weaponizing the AR15

Post by TL1000RSquid » Fri Jul 31, 2020 7:09 am

LT USN (Ret.) wrote:
Fri Jul 31, 2020 6:40 am
Good stuff. I had already smoothed out the buffer tube from some other thread you mentioned it in. It really did help.

Plus, from an earlier thread on lubes, I use the synthetic oil 5w-30 and Mystery Oil combo recipe you recommended for most of my firearms.
If your smoothing the buffer tube, upgraded spring can help smoothen/quiet it as well, been running flatwire ones in my setups.
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Re: Weaponizing the AR15

Post by Weapon » Sat Aug 01, 2020 12:04 pm

Back to a some DIY tuning -
The bolt is often another area that can benefit from a bit of polishing. I typically polish all the flats on the bolt with a Dremel and felt wheel loaded with Flitz or Maas polish. It doesn’t take much but can smooth cycling considerably:
ABC5F360-0B5F-447A-81DE-FE42EE8787B5.jpeg
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While you have the bolt out, some extractor cleanup and polishing can improve reliability. This is especially true of ARs with shorter gas systems. I polish the face of the extractor to a fairly high polish and then very lightly polish the flats around the pin hole to make sure there is no binding and it can rock freely in the bolt:
C85A0496-5082-4C58-814F-E75B0F6D16CB.jpeg
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On any AR with a short gas system, it is a good idea to add a minor $5 upgrade to increase extractor tension and reliability. M4 profiles often have issues with extraction due to how violently they cycle (if left with stock gas tuning). This very minor spring and o-ring upgrade will fix that issue 99% of the time:
https://bravocompanyusa.com/bcm-extract ... grade-kit/

Another minor upgrade that can have much more of an effect on smooth cycling than you would expect is JP’s single piece gas ring. It fits most bolts and carriers with no problems and reduces friction between the bolt and bolt carrier...very cool but it could also clean the inside of the bolt carrier...wait...it does that too:
https://www.brownells.com/rifle-parts/g ... 68370.aspx

Tons of additional info will be added on the bolt and extractor cleanup later. I have somehow lost some pics and it will not make much sense without the pics.
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Bolt Upgrades

Post by Weapon » Sat Aug 01, 2020 12:45 pm

If the AR design has an Achilles heel, it is very likely the bolt. The US military rates average AR bolt life as a mere 7,500 rounds but many which are not used in burst fire last much longer. While most of them will not fail until they have fired more than ten or twenty thousand rounds, having a spare bolt is a good idea. Tuning the gas system will make all of the moving parts in an AR last longer but, if you need extreme reliability, several companies have made upgrades to the original design and/or materials.

Of course JP is one of them. JP’s enhanced bolt assembly is made from SAE 9310 steel with a DLC coating and radiused bolt lugs to increase service life up to 60,000 rounds. Due to the radiused bolt lugs and DLC coating, it also cycles more smoothly than milspec bolts. Unfortunately, it’s a premium quality part so it is has the price to match and costs as much as many complete bolt carrier groups:
https://www.brownells.com/rifle-parts/b ... 40077.aspx

Another very high speed AR bolt is the HMB bolt manufactured by Young manufacturing. This bolt eliminates the pass through cam pin hole in the bolt and replaces it with a cam pin socket and radiused cam pin design. This gets rid of the weak point of milspec bolt by significantly increasing the amount of metal at the cam pin location. The cam pin hole is almost always the point of failure for milspec bolts so this is a nice upgrade...but, yet again, premium part so premium price:
https://youngmanufacturing.net/product/hmb-bolt/

For comparison, a standard milspec bolt is maybe $45-$55
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ARs that Shave Brass

Post by Weapon » Sat Aug 01, 2020 6:58 pm

I haven’t seen too many properly gassed ARs that will damage brass but I have seen a few. Usually, it is due to an burr or edge that was left on the verge of razor sharp by the manufacturer. I reload .223/5.56 and, while finding brass is usually is fairly easy, the occasional election and/or pandemic can make it hard to come by. So, I don’t like it when my rifles tear it up.

If you find brass shavings in your AR or notice scrapes in your brass, the first places to check are the extractor and the extractor cut in the bolt. More specifically, the lower edge on the extractor and the edge where the extractor groove in the bolt meets the breachface. I have gotten into the habit of putting a very slight radius on those edges. A very light radius on those edges will often fix brass shaving and also make it easier for the extractor to slip onto the brass. The former keeps your brass in top shape and the latter slightly increases reliability. Not bad for a couple light strokes with a fine cut needle file.

I will add pics of all of this later if it is not entirely clear.

The bolt lugs can also damage brass - especially the back of the bottom bolt lugs that rake over the top rounds in the magazine on the back stroke of cycling. I also slightly radius those edges to make sure brass doesn’t get shaved. Yet, again it can also slightly improve cycling and reliability.

If you look closely at most of the $100+ bolts on the market, you will find they have added a slight radius in these locations. Credit to those folks - they paid attention.
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ncjw
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Re: Weaponizing the AR15

Post by ncjw » Sun Aug 02, 2020 12:11 pm

I second the recommendation of the Toolcraft BCG's, especially in NiB. They are slippery suckers, but apparently hard to find now in the current environment.

I have them in .223, 6.5 Grendel and .308. Not all of my AR's have them, but if one of the non-Toolcraft BCG's ever fails, it will be replaced with a Toolcraft NiB. I just can't see upgrading a BCG that is currently running fine.

Keep up the good work (I can't wait until we get to the posts on polishing the buffer spring detent...)
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