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Ron(formerly Tangle)

Posts: 49
Reply with quote  #1 
In another thread, JD asked,
"...Also are there any upgrades that are not to pricey that would make one of the entry guns do better in such a test..."

Because this is AR specific, I put the answer here in "All Things AR".

Typical off the rack ARs are over gassed. That is, the gas pressure that cycles the action is higher than it needs to be. That's good and bad. It's good because the extra pressure will keep the gun running when it gets dry and dirty. It's bad because when the gun is clean and lubed, that extra pressure is slamming the bolt carrier group which increases recoil reaction and probably increases wear somewhat.

One thing that I think that will enhance performance in terms of accuracy, lifetime, and reduced recoil of the AR is an adjustable gas block; they go for about $100. I have one on every one of my AR uppers. Well, it's side bar time:

One of the things that makes an AR unique is it's lower-upper design. One could buy one lower (FFL required). Or if one so desired, he could buy an 80% finished lower, no FFL or registration is required. But he would have to finish the lower which requires machining but many have used a drill press and the templates that come with the "ghost" lower to do the finish work. A caveat is that, once finished, the unregistered lower cannot be sold unless he registers it as a firearm. 

Anyway one can build this one lower to meet his needs/preferences, e.g. custom trigger, ambi-safety, mag release - even preferred buffer tube and butt stocks. Then he could buy one upper receiver, say a 16" barrel and simply attach the upper to the lower with nothing more than pushing in the two takedown pins.

Then suppose a coyote hunt comes up and the guy wants a longer barrel and maybe more accuracy but doesn't want to modify his 16" home defense upper. So he gets an upper with a 18 - 20" barrel and mounts it on his custom lower. One custom lower, infinite possible uppers.

Suppose he wants to change to a 6.5 mm caliber cartridge. Same lower, but new upper with the 6.5 mm Grendel barrel and possibly a different magazine and bolt - bolt only not bolt carrier group. I can't remember off the top of my head if the 6.5 uses the same mags and bolts.

Anyway that's just one of the beauties of the AR design. And now back to our regularly scheduled program.

The adjustable gas block lets you adjust the gas pressure for a given round or rounds while minimizing over gassing and recoil. My favorite is the JP Enterprises side adjusting block. Unfortunately, it won't fit under all handguards and because it is adjusted from the side, the handguard can and usually does, block access to the adjustment screw.

My next favorite is the SLR adjustable block. The SLR, like just about all other brands, adjusts from the front of the block and I have yet to find a handguard that wouldn't work with the SLR.

Unfortunately most off the rack ARs have "drop in", non-floating handguards and a front sight tower pinned to the barrel. So to add an adjustable gas block you have to find an adjustable gas block that replaces the sight tower. I believe JP Enterprises has those.

Another thing I change is the gas system length. Typical off the rack ARs have carbine length gas systems. AR gas systems come in four lengths, listed from shortest to longest: pistol, carbine, mid, and rifle which are about 4-1/2", 7-1/2", 9-1/2", and 12-1/2" respectively and those lengths are nominal, not precise.

Here's what is significant about gas system lengths. The shorter the system, the higher the gas operating pressure which forces the brass case against the chamber with more force which makes extraction harder, which places more stress on the extractor.

The further down the barrel the gas port is located, the lower the gas pressure and hence there is less pressure in the case and less force is required for extraction. My strong preference is for the mid length - even over rifle length for longer barrels. But having said that I do have rifle length systems on 18" barrels.

The only practical way to change the gas system length is to replace the barrel with the length you want. Good barrels can go for about $200 - $250. Unless you're trying to squeeze every small bit of accuracy out of your gun, you really don't need $500+ barrels.

Barrel replacement offers many options: You could go with a different length barrel, a preferred twist rate, finish type, essentially melonite or chrome lined, and barrel profile from ultralights to heavy and even fluted.

Yet another option that comes via barrel replacement is barrel seating. Barrel seating on an AR consists of installing the barrel in the receiver so that it's as solid of a mount as it can be. This is mostly to keep the barrel-receiver stable which can improve accuracy - depending on how well the barrel was fit initially.

Most of us will have to accept the receiver to barrel fit as it is. Some have access to a number of barrels and/or receivers and get to pick and fit. We typically are stuck with the barrel to receiver fit we have. But there is one thing we can do - Lock-Tite the barrel. We have to be careful here. There is Lock-Tite and there is Lock-Tite. And no matter what you hear or read, DO NOT USE ROCK-SET. If you do, there's a chance you'll never be able to separate the barrel from the receiver. Heat won't do it. The recommended way is to immerse the parts in water overnight, but even that doesn't always work.

I use blue Lock-Tite. It will melt if the receiver barrel temperature gets too high but OTOH if you use red Lock-Tite, you will have to heat the barrel and receiver to the high melting point of the red Lock-Tite to get the barrel to separate from the receiver.

One guy uses a green Lock-Tite and I haven't looked into that yet so I can't speak to that, except it is a high temp and it appears to be thicker, i.e. less runny than the red.

Anyway what you do is grease the receiver threads so if some of the Lock-Tite oozes out, it won't lock the barrel nut threads. Spread the Lock-Tite liberally over the barrel extension and slide it into the receiver. Wipe any and all Lock-Tite off the outside of the assembly. Re-grease the receiver threads and the front of the barrel shoulder that the barrel nut will bear on.

Install the barrel nut, time and torque and let it set at least overnight.

If you do change barrels, before you install the new barrel, there is one more thing I personally recommend - true the front of the receiver. We assume the receiver is machined accurately, but that doesn't mean it is. What can happen is a slightly out of true receiver can put the barrel at a very slight angle. We zero at 100 yards but when we shoot at 200 - 300 yards, we see an offset beyond just bullet drop. For example I've seen horizontal offsets of about 2 inches at 200 from a 100 yard zero. When we true the front of the receiver, the centerline of the barrel is more closely aligned with the centerline of the receiver.

Brownells makes a simple tool you use with a hand drill to true the receiver - it's easy. This also provides another potential benefit. Sometimes, barrel nuts will just not align suitably with the receiver. This is a tough situation to fix - unless you have a receiver truing tool. Since the tool takes very small amounts off the front of the receiver, a bit of "fitting" using the tool can let the barrel nut come on around to where it needs to be. It's almost a perfect way to time a stubborn barrel nut.

If you change out the barrel for one with a longer gas system, you'll likely have to change the handguard as well, and likely replace the front sight tower with a different system. But that too comes with options: length, weight, M-Lok or Key-Mod and in all likelihood you'll want a free-floating handguard. The military had a list of improvements for the M-4, one was a better trigger (amen to that) and another was a floating handguard - just sayin'.

A floating handguard is gonna go for somewhere between $100 - $200 and there are some "name" types that are even more - you just don't need "even more".

The last thing is the trigger. Off the rack ARs have awful triggers typically. If your AR is going to serve as a home defense gun, you may not want to mess with the trigger. If it's a hunting gun then a good trigger can make a big difference. I use Geissele National Match triggers in my ARs, yes, even my HD AR - I just set the trigger pull higher than my other triggers. On the ARs I shoot for accuracy, I adjust the trigger for about a 1-1/4 lb first stage and about a 1 lb second stage.

Good triggers are gonna go for about $220 - Geissele National Match and CMC 2+2. The Geissele triggers are all two piece - trigger and hammer and require some effort to get in. The CMC 2+2 is a module and basically drops in although it does require removing the safety - I think - been a while since I installed one.

Speaking of triggers, there are single stage and two stage. Without batting an eye, get a two stage. Unless you are heavily competing, stay away from single stage triggers. I have both. Geissele NM's are 2 stage; my American Gold is single stage. If you have to ask what's the difference, just get a 2 stage - trust me!

One last trigger thing. If you get into trigger "tuning" of a two stage trigger, you want the first stage to be about the same or less than the second stage break. If you get the first stage heavier than the second stage, the force on your finger due to the first stage can significantly mask the "wall" of the second stage and sometime you can pull straight through the second stage without feeling it. And sometimes that may be desirable, but for accuracy purposes, it's nice to be able to pull though the first stage and hit the "wall" of the second stage. You now have a 1911 type break.

To be sure you don't pull through the wall, the second stage needs to be heavy enough to stand out above the first stage. For example, I set my range/hunting trigger to a 1-1/4 lb first stage and about the same for the second stage although I have found a second stage break of 1 lb works pretty good with the 1-1/4 lb first stage.

Lubing and cleaning. Contrary to perception perhaps, I loath cleaning - I don't mind lubing, but I don't like cleaning. That being said, I clean my barrel with a brass brush and some kind of foaming cleaner although from what I see it ain't foam by the time it gets to the bore. I scrub it pretty good and if I can, I let it set wet, usually while I set up targets, etc.

I run patches until it's dry and then when I'm too embarrassed not to, I run a brass brush with copper remover on it and let it set as long as I can, which is typically as long as it takes me to replace the brass brush with a patch and start swabbing.

The BCG: I seem to like mine filthy??? Oh, I might wipe them down frequently with a rag, but it is rare that I break it down and deep clean. I use oil, FP-10 or Weapon Shield exclusively and NEVER, NEVER grease, and I don't care what your sargeant told you to use. I've used grease in an AR and when I saw the  results I knew I would never put grease in my AR again. 

I put about a drop of oil on each of the bolt lugs - they catch some forces, especially the rear of the lugs. I put two drops of oil down the bolt cavity (with the bolt in place) being sure that one drop hits the extractor.

I put one drop on each of the top front rails and makes sure the oil runs down into the cam pin. I spread one drop on the rear top rails and one drop on the bottom rails. I generally have oil on my fingers by this point so I rub the oiliest on on the bottom of the BCG where it runs against the rounds. And that's it - nothing in the upper receiver.

In the bottom receiver, I do use a bit of Gun Butter grease on the sears. I oil the hammer pin and trigger pin and safety where it contacts the frame. Occasionally, I spray out the lower with brake fluid and relube.

Ugh, I'm tired just thinking about it.

Junior Member
Posts: 16
Reply with quote  #2 
An inexpensive way to slow down the bolt on an AR is to install a Tubb's buffer spring.

Put one in my carbine, and it does make a difference.

Posts: 62
Reply with quote  #3 
Originally Posted by Quinn
An inexpensive way to slow down the bolt on an AR is to install a Tubb's buffer spring.

Put one in my carbine, and it does make a difference.

Quinn, Thanks for posting the video, as it's very interesting, and well done, plus the information that's provided, in the video, is very informative.


Senior Member
Posts: 304
Reply with quote  #4 
Entry guns are specialized-Usually have pointy flash hiders or a can, short stock for use with a vest, a PEQ-2, sometimes a Master Key (870 mounted under the barrel). Since they usually are 14.5" 12" or 10" an adjustable gas block is a good idea; better than putting bent and looped rifle length gas tubes under the short handguards of a 10" barrel like we did for the scouts' CAR-15's. (The XM177E2 had been withdrawn, and the M4 wouldn't be issued for about 2 more years) 
Grease on the bolt of a 16? That would be one ate-up Sergeant! 

I know you meant entry-level guns, I was just funnin'' ya! 

Very informative post lots of useful info!

Avatar / Picture

Posts: 1,699
Reply with quote  #5 

Yes, I was referring to entry level guns, those costing the least.  All the companies have their entry level models like the Oracle. Sportical or Ruger 556.  I know that you can take an 870 Express install $20 in parts and have the same quality as the 870 Police but of course with different finish and furniture.    Tangle gets great results from his test but he builds his AR's and they are all high end builds and built for accuracy.  I wondered what the results would be with the off the rack entry level guns so I asked the question.    Asking Tangle an AR question is like opening an Encyclopedia of gun knowledge.  Tangle and Quinn gave anyone wanting to upgrade their AR a lot of good info.

I fired the Car-15 in 9mm and wanted that for my HRT but the Admin Pukes in Tallahassee insisted we had AR's and didn't need anything else.  F**k** ADMIN PUkE never been there done that G** D*&^ useless piles a Dog S*(^ .   We train with other team and they all had MP5's and we show up with Surplus A2's and look like the Keystone Cops.   The reason I wanted the Colt Car-15s is I had two Colt Armorers on the Team so no further training was needed.  Also, the MP5's had to go back to Germany for most repairs back in those days.   The Car's could be repaired in house or sent back to Colt.   F**k*** Admin Puke never been there done that............wait, I already said that.

JD McGuire, Owner
AI&P Tactical, LLC
Remington LE Armorer
Mossberg LE Armorer

Senior Member
Posts: 167
Reply with quote  #6 
A correctly assembled rifle mitigates many issues. I pay on the front end, so I don't have to pay on the back-end. Barrels are thermal-fit to the upper, gas-port is properly sized for suppressed and unsuppressed use (in my case, 0.074" on a 14.5" middy to be used with Surefire cans, specifically a mini, in my case), and I use REV E current gen military approved CLP, because I don't play games with "flavor of the week" lubes that will sue you one day, and gum up your weapon the next day.

Find a manufacturer that will build to a high standard so that you don't have to come behind them and clean up the mess. If it's a department issued gun, I would be VERY leery of putting "adjustable" anything on it. I once shot a course with a Surefire rep who had installed such a gas-block on his gun, and it was tuned very VERY nicely with his can! For about 50 rounds, until it got dirty and short-stroked like a boss.

Correct gas-port sizing is done using the established buffer weight/spring, and using high-speed videography on a full-auto platform, and the manufacturer should be responsible for fielding the product, tuned as such.

The reason I advise to purchase quality initially instead of multiple band-aids later, is because the current MRBS of the M4 platform is sitting on about 12,000 rounds. There is NO WAY to know whether the change YOU made has made that go up, or down. The manufacturer should have done the homework for you and fielded a working platform. Presuming they have, when you alter it...who knows? You won't unless you shoot it enough to burn the barrel out. Stick with known parameters. 

For an entry-gun/SBR, stick with CRANE's spec. They did all the hard work for you, just mirror the specs and motor on. For a 14.5" gun, there are several options the government/ DoD is currently using. Pick one and go with it.

As far as thermal fit upper/barrel junctions, honestly, it's just nice. Military/DoD testing has failed to uncover any appreciable value in it. It's still sexy and I am a fan of it.


Junior Member
Posts: 15
Reply with quote  #7 
A H2 buffer and the Tubb flat wire buffer spring will do wonders.  Tubb also makes an improved extractor spring.

A more unknown mod is to slightly shorten the ejector spring.  Instead of your brass being thrown 10-15 feet at 4 o'clock, you can get it to throw somewhere between 1 and 3 o'clock.  Keeps your brass from hitting the guy or gal to your right at the range and typically throws the brass into a small, neat little pile.  Great if you reload.

Do a YouTube or internet search on how to do it.

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