I used some scrap pieces of wood and sandwiched my upper in a bench vise. Don't think it hurt anything, gun runs and shoots 1-2 moa depending on ammo.

MI URR.  Doesn’t get much better than that.

Plastixevolution blocks work well. Make sure you have a good wrench; my standard armorer tool wouldn't hold the torque. I bought a Precision Reflex wrench and it laughed at the torque. Very solid, stable grip.

Use a reaction rod (Midwest, KAC, anyone really). It's the only good solution to torque properly.

The straight style of reaction rod (e.g. Geissele's version) is great for torquing and removing muzzle devices but a horrible idea for installing barrel nuts.

With all the straight reaction rods, when installing a barrel nut, ALL the torque goes into the barrel extension index pin. The MI URR, and similar, have a "sail" that positively engages the inside of the upper to keep it from rotating, so the index pin doesn't have to take the torque.

Think about what you're threading onto what. A muzzle device threads onto the barrel, so you want to hold the barrel steady. Straight rod, or simply clamping the barrel in a vise, is great for that. A barrel nut threads onto the upper itself. You need to anchor the upper more than the barrel. A reaction rod with the "sail" or a good block/clamshell device that doesn't rely on the takedown and pivot pin ears to hold it firm is what you need.

The barrel extension on an AR-15 is torqued to 150 ft-lbs before being pinned in.  I'm making the assumption that an AR-10 has a similar spec, and if so I don't think I'm all that concerned about shearing the index pin or un-torquing the barrel extension.

In fact, I think keeping the upper receiver out of the equation is probably better.  Introducing any rotational force where the receiver meets the index pin has a higher chance of shearing the index pin or at the very least wallowing out the notch in the receiver for it.

That's the general conclusion i've come to looking this up. I'm thinking the pastix blocks for barrel nuts and their soft jaws for muzzle devices. Just waiting to hear back from them on whether or not the jaws are good for the 20-30 fl/lbs most call for. Plastix says they're good for resisting "light rotation" but that at face value is pretty subjective.

That is completely and totally incorrect and clamping the barrel only (using a standard RR or barrel clamps) is what risks shearing the index pin.

Think about it.  Which part does the barrel nut have the most contact with?  The barrel extension flange or the upper threads?  The answer is the upper threads, meaning when you torque the barrel nut most of that force is being imparted on the receiver, rotating the index pin slot against the index pin potentially shearing it.  You’re introducing a lot of unsupported rotational force where the index pin meets the receiver.

There have been no shortage of “i sheared off my index pin/damaged my upper” threads in relation to using a standard RR.  That won’t happen with receiver blocks or a device like the URR.

Also, the extension isn’t “pinned” to the barrel, there is simply a hole in the extension that a pin is pressed into, it does nothing to hold the barrel and extension together.

Anyone have issues using D&H .308 mags with their M5?

See my thread in the link below.

https://www.ar15.com/forums/AR-15/Anyone-else-having-issues-with-DandH-308-Mag/17-755753/

Had the same thing with my all Aero M5 and the lime green follower mags. Mine was happening usually on rounds only on one side the mag or the other, usually the right. I did swap in some springs I had laying around from some M14 mags and they worked pretty good after that. It was just a PITA to do all my mags and I sold all of them down the road. Only running pmags now.

It makes me feel better to know it wasn't just my rifle.  I may grab a couple M14 mag springs and see if they help.  If that fixes them I may just keep these as range mags.  I'll probably be sticking to PMags going forward too.

Most of this was me (wind was almost nonexistent and at my back when it was even perceptible), but the creed seems to like 140 Gold Dots at 200.


IMG_20200822_131824_677 by Professor Horseyhead, on Flickr

I'm trying to figure out what to do with my two remaining lowers.  I have one M5 with an 18" barrel and rifle length gas, in 6.5CM with a 3-15X on it.  It serves as my DMR gun and my two precision bolt guns are also 6.5CM.  So I don't have a .308 anywhere in my inventory but a very seldomly used hunting rifle.  I really love the idea of a 14.5-16" .308 kind of like the KAC SR-25 APC but is it worth the squeeze over my 18" 6.5?

Option 1: Build out a 16" 6.5CM
Option 2: Build out a 16" 308
Option 3: Do nothing

12.5" 308

@Trey-W

I’m getting .295” on the lugs and .045” on the BF depth on the Fulton bolt.

My micrometer was throwing a fit, I think the battery was dying, but that’s what I came up with.

Aero OD Anodized
Noveske NSR 11”
Dracos 13.5”

It's still work in progress, but here's my M5 so far.





Aero M5 Upper/lower/rail, black nitride 18" barrel and bolt carrier group.

B5 grip and buttstock

IOR 1.5-8 Trident, ADM mount [temporary]

Geissele desert dirt color 7.62 charging handle

Surefire 7.62 three prong

Have a Geissele desert dirt color buffer tube in the mail, still waiting on them to make some more DDC BUIS' and 35mm scope mounts

Can someone with the 12" R-One Mlok handguard measure to this line and tell me how far it is to the end of the handguard?

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Bump

Now i'm going to introduce you two to reality.

The fact of the matter is that the tolerance stacking of any reaction rod with receiver rail or takedown pin capture isn't going to overcome the allowable tolerance of the index pin notch.

They may limit movement and deformation of the notch by the pin when too much torque is applied, but they will not stop it from happening altogether.

In my world (being prior professional contract armorer and current DoD ordnance), i have yet to shear a single index pin ever, or see it happen ever. This includes the use of receiver blocks, barrel blocks, reaction rods, and some WECSOG shit we used to do back in the day.

The fact of the matter is that the PROPER use of torque and quality parts is the most important part of building.

If you are shearing index pins, you are DOING someing wrong, or have sub quality parts. Quality parts, when torqued to spec, do not shear pins.

Using an overly expensive build tool that actually allows you to hide the fact you have sub-quality parts or allows you to excessivly torque your equipment is NOT going to make you a better builder or make for a better gun.

Now, regarding the torque applied to the pin vs. receiver, etc., here's some tips.

If you have any play between the notch and index pin(side to side movememt, however small) this can lead to fsb misalignment as generally the play will favor one side more than the other.

To account for this, figure out which side the notch favors and choose the most appropriate build tool.

If the play is to the left (Operators Point of View or OPV. Meaning looking down the sight s from the rear towards the muzzle), you will want to favor the index pin to the right to keep the fsb/gas block from being canted left.

To do this, use a reaction rod type system as the barrel nut will make the receiver pivot with it to the left while keeping the index pin favored right.

If your index pin notch is excessive and favors right, use a reciever clamp system as this will cause the barrel and pin to turn to favor to the left.

Now for the best part. If you are building correctly with proper tools, parts, and following the procedure, if you only have a single retention method (let's say receiver clamps), you can actually hold the barrel to the side you wish by hand and apply the necessary torque to the barrel nut and the index pin will stay put.  Have a fellow armorer hold the fsb to the side you need while performing the final torque and it will stay where you need it to.

Meaning there is not enough torque applied to the index pin during a proper build procedure to sheer it off. Unless if course you are using shit parts or a good company happened to put out a rare lemon.

Remember, keep the interface between the barrel extension and receiver dry (you want friction here) and apply mil spec moly grease to the threads AND the face of the barrel extension that contacts the barrel nut to reduce friction and applied lateral force to the index pin, and keep your ugga duggas to the bare minimum as required by the instructions, procedure, or tech manual.

Everything else is a crutch or an excuse.

That must be why we have nearly weekly “I damaged my upper/sheared an index pin while using a RR” threads here.

You’re not the only one with experience building guns here and more than enough people have damaged their stuff using the incorrect tools for the job.  Can you get away with it a large majority of the time?  Sure.  I’ve used RRs to install and remove barrel nuts before without issue.  Does it increase your chance of damaging stuff?  Yep, sure as hell does, regardless of the quality of parts.  

You keep on doing you, but recommending that people be overly careful and not cut corners during the assembly of their parts will never steer anyone wrong, spanning the vast breadth of experience levels that frequent these forums.

Yeah I switched to PMAGs and all the issues went away. Too bad, because I liked the steel construction of the D&H mags.

We have those threads because we also have an overabundance of people who think that AR's are over-glorified lego sets.

There are a lot of people that don't know what they don't know.

This kind of justifucation and acceptance of thes amateurs who constantly damage their equipment and dismissal of professional experience such as mine is what leads to a continual dumbing down of the culture and is a large reason why there are fewer and fewer professionals willing to assist in these forums. It's idiocracy in action.

Based on the "knowledge" i've seen some people spew in the tech forums, i'm going to say that "vast breadth of experience" you seen to think exists here is more like the shallow end of the kiddie pool.

With the exception of a few such as CD, arfcom tech forums are severely lacking in real world experience.  

You may continue to hold on to your belief that action rods increase the probability of damaging equipment. That's fine. Conformation bias is a thing.  I understand that this is the way of the world and you are welcome to your "opinion". Just do keep in mind that opinion is not as relevent as ecperience. At least try to.

Get off your high horse. If anything, what I said only agrees with what you've said. I tried to clarify why only the correct tool should be used for the job. A reaction rod is NOT the correct tool for installing a barrel nut unless it also engages the receiver. Period. Has it been done without breaking shit? Yes, many times. Should it be done? No. If you disagree with that, then I have one more place I'll add to my do-not-buy-from list.

Again, just because you're an "expert" doesn't mean you're the only one that knows a few things.

These types of responses are what i've come to expect from arfcom. You can lead a horse to water and all that.

You literally don't know enough to know what you don't know.

By your uneducated "beliefs", literally every military authorized special tooling acceptable for use in the process of installing a barrel in the M16/M4 platfom is the wrong type of tool.

You have not actually thought out the process and forces involved during the process and how each part acts and interacts during the process.

Your ignorance and lack of critical thinking is glaringly obvious.

Wallow in your amateur hour cesspool of ignorance then.

Toodles.

Meh, I use a Bev block for assembling ARs. It works well, can be used for lowers, and didn’t cost $100+.

About the only tool i would recommend NOT to be used is the upper receiver jigs that only attach via the takedown pin lugs.

So long as the -23&P standards are being followed and the parts used aren't complete crap, the vast majority of tools that engage either the full upper (receiver clamps) or the barrel (action rods/barrel blocks/bev block), are generally gtg.

I have used brownells action rods to great effect (both 5.56 and 30 cal) since 2016 for the fraction of the price of the G-rod and have yet to sheer or break a single index pin on hundreds of builds, including many HK 416 and MR556 builds.

Meaning the index pin or index pin notch damage is a user interface issue, not a tool issue.

Just added the [desert dirt color] DDC buffer tube, need the DDC BUIS' and scope mount and it will be complete. Now if Geissele would start pumping out those DDC parts.

My work in progress, DPMS lower and BCG, Aero upper, Ballistic Advantage .308 barrel, Superlative Arms AGB,  B5 stock. I’m waiting for an M5 Atlas S-1 to be in stock and somehow I forgot the gas tube, but that’s on the way. Choosing a scope is kicking my butt.  

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Pm sent with measurements

What buffer weights are you guys using in your carbine extensions for .308?  Parting out a build.  Thanks!

Using AR15 receiver extension:

https://www.kakindustry.com/lr308-carbine-buffer-heavy

I used the Aero kit with the 3.8 oz short buffer

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Anyone know where one could get a M5 complete upper (fde)... not sure if I want 18 or 20  but .308 should get me started then can always add a different upper.... later maybe.. but would like to find and upper now just to complete this lower.....

TIA

I checked a couple of the usual suspects and I couldn't find any in stock.  Found a stripped upper at Primary Arms

Any other place i should check other than aero/primary arms/middway...

Arm or Ally has them

Check Granite Ridge.

ETA: FDE complete upper for $161.49

Arm .... ally ?

Looking for plug n play...

It's Armor Ally.

There are a couple of barreled uppers at Granite Ridge.

Standard Aero in four builds, all run fine, with and w/o suppressor with a variety of ammo from 110gr TAP to 168gr hand loads.

Ok Guess I am gonna piece one together... first-timer at this..

Ordered M5E1 fde complete upper receiver

Now to buy a barrel...

18 or 20?  Aero has them and they are roughly $10 price difference.

I went with an 18" for my 6.5CM.  It's purpose is as a DMR type rifle

Same here.  An 18" 6.5 Creedmoor felt like the sweet spot for a DMR inspired build.  It's a little heavier than I initially planned at 12.5 lbs with a loaded magazine, but I have AR15s as my lightweight guns (7-9 lbs).  I could save about a pound in the barrel (Craddock Precision to Faxon) and a pound in the optic (Athlon Ares BTR to SWFA Ultralight) and come in under budget if I really wanted to save weight, but my 6.5 Grendel fits that role well already.  If I wanted to do a dedicated bench rest rifle, I'd probably go with a bolt action with a 22"-26" barrel.  This was a "get a big frame semi auto before California makes it even harder than it is now" type of build.  

Bought the aero 18 .308 barrel


Now to locate handgaurd and gas tube stuff...


Already plannin a 6.5 build

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Ok here is my dumb question of the day.

On an 18 brl, what length handguard should I be looking to buy 12/15? This will go on a aero m5e1 upper

That is a personal preference, both will work.

Personally, I prefer to use the longest handguard possible for all my AR builds.