308 AR10 Build Info/Picture Thread

[jLorenzo]

How fucked am I? Aero rifle length gas tube, aero enhanced upper, Rainier Match 18" rifle gas. The gas tube has a slight shoulder that wont let it go into the upper any further. I have a SA adjustable block coming tomorrow but this shit doesn't look right to me.

Also heres a borescope of the barrel, only ran 2 patches of patch out through it, no scrubbing or anything. Looks like I'm gonna scrub some.

 

[msgriff]

How fucked am I? Aero rifle length gas tube, aero enhanced upper, Rainier Match 18" rifle gas. The gas tube has a slight shoulder that wont let it go into the upper any further. I have a SA adjustable block coming tomorrow but this shit doesn't look right to me.

Also heres a borescope of the barrel, only ran 2 patches of patch out through it, no scrubbing or anything. Looks like I'm gonna scrub some.

You can measure the gas tube to see if it is in spec or if it's the upper. Mil-Spec gas tubes are 0.180" (+/- 0.001") OD for the larger diameter area.

Additional specs not related to your issue: 0.170" (+/- 0.004") for the smaller diameter area, which extends 2.33" from the flared end. The OD spec for the flared end is 0.1800" (-0.0006").

There are heavy wall gas tube that are not Mil-Spec, that doesn't look like one of them. I don't know what Aero specs for the gas tube opening of their Enhanced uppers, but their anno is thicker than most.

 

[357Max]

A drill bit will fix that in 2 min.

 

[Cascade Hemi]

How fucked am I? Aero rifle length gas tube, aero enhanced upper, Rainier Match 18" rifle gas. The gas tube has a slight shoulder that wont let it go into the upper any further. I have a SA adjustable block coming tomorrow but this shit doesn't look right to me.

Also heres a borescope of the barrel, only ran 2 patches of patch out through it, no scrubbing or anything. Looks like I'm gonna scrub some.

Take a 35cal bronze brush, spray it down with FreeAll (or equivalent penetrating oil), and run the brush down the bore (back and forth) 100 times. Reapply the oil every 10 to 20 strokes. When you're done, scrub (sawing motion) the bore with a 30cal patch wrapped around a nylon 30cal brush, using Iosso or JB. One or two total passes. Most of that will clean up.

Return and replace the gas tube.

 

[jLorenzo]

Used Freeall and bronze brush. little better, if it shoots, good if not its going back. That is all I really care about.

 

[jLorenzo]

A drill bit will fix that in 2 min.

I hoping to not have to take a drill to my brand new stuff, perhaps I will though. Not before I try another tube.

 

[JR1200W3]

The bore on that barrel doesn't look awesome but I don't think it looks atrocious either. If you're talking about the horizontal/ perpendicular tooling marks, while not pretty, I don't think it will make the barrel shoot poorly. The brown discoloration is puzzling, possibly alarming. Is that the solvent you used?

My Ultra Match looks just like a polished button rifled barrel. Which it is. What you're seeing is what I think you get at that price point. I'd definitely just shoot it and see how it does. The good news is the gas port doesn't look too bad. I'd watch that with a borescope and see how the port erosion looks over time.

 

[Cascade Hemi]

The bore on that barrel doesn't look awesome but I don't think it looks atrocious either. If you're talking about the horizontal/ perpendicular tooling marks, while not pretty, I don't think it will make the barrel shoot poorly. The brown discoloration is puzzling, possibly alarming. Is that the solvent you used?

My Ultra Match looks just like a polished button rifled barrel. Which it is. What you're seeing is what I think you get at that price point. I'd definitely just shoot it and see how it does. The good news is the gas port doesn't look too bad. I'd watch that with a borescope and see how the port erosion looks over time.

I believe what you're seeing is left over lubricant from the buttoning process. It gets pressed into the metal and takes some time to come out. Pretty sure a little Iosso or JB will take it out, although it'll come out when he shoots it.

 

[jLorenzo]

I got a new gas tube and cleaned the hole in the upper extension with a 22 cal bronze brush and it finally went together. I now have 2 extra tubes though. Time to build more I guess.

 

[x248716x]

How fucked am I? Aero rifle length gas tube, aero enhanced upper, Rainier Match 18" rifle gas. The gas tube has a slight shoulder that wont let it go into the upper any further. I have a SA adjustable block coming tomorrow but this shit doesn't look right to me.

Also heres a borescope of the barrel, only ran 2 patches of patch out through it, no scrubbing or anything. Looks like I'm gonna scrub some.

is the tooth on the barrel nut touching the gas tube? IIRC, it helps to time the barrel nut, even though the gas tube sorta clears the teeth. just to give it maximum clearance. But it's been a while since I assembled mine (Aero enhanced M5 upper).

 

[jLorenzo]

is the tooth on the barrel nut touching the gas tube? IIRC, it helps to time the barrel nut, even though the gas tube sorta clears the teeth. just to give it maximum clearance. But it's been a while since I assembled mine (Aero enhanced M5 upper).

I thought maybe but no you dont have to fit the tube through the teeth with the enhance upper. The tube will clear no matter what. The hole the tube goes in needed brushed out really well. Real tight before I brushed it out.

 

[jLorenzo]

I think the Rainier match is going back, 2 handloads 175 nosler CC w/42.5gr of Varget, 155 SMK with 42.8gr AR comp. I don't see this breaking in or settling down to anything I would be impressed with.

 

[JR1200W3]

I think the Rainier match is going back, 2 handloads 175 nosler CC w/42.5gr of Varget, 155 SMK with 42.8gr AR comp. I don't see this breaking in or settling down to anything I would be impressed with.

JC, that's bad

 

[ALPHADOG]

1. Aero Upper 6.5 CM 24”, SS, Hvy BB .930 dia. At Muzzel, 1-8 twist
2. Aero M5 Lower
3. JP Bolt Carrier
4. JP .308 High Pressure Bolt
5. Giselle Buffer Spring
6. Radian Trigger
7. Radian Charging Handle
8. Juggernaut Hellfire System
9. Aero Lower Parts Kit
10. Precision Armament M11 Muzzle Brake
11. Magpul PRR Gen 3 Stock
12. Hogue Grip
13. Area 419 12” ARCA rail
14. Leupold MK5 HD 3.6x18
    

 

[jLorenzo]

JC, that's bad

To be fair I did my zeroing on that tatget so a few of those that are way out are from that but still it wasnt even really grouping half the time.

 

[JR1200W3]

To be fair I did my zeroing on that tatget so a few of those that are way out are from that but still it wasnt even really grouping half the time.

Just curious, why you didn't buy the ultra match version?

 

[jLorenzo]

Just curious, why you didn't buy the ultra match version?

The match had a couple people in the reviews claiming good results. Probably shouldve gone with the ultramatch. Not really a fan of flutes either

 

[Cascade Hemi]

The match had a couple people in the reviews claiming good results. Probably shouldve gone with the ultramatch. Not really a fan of flutes either

Post some pictures of your upper build. Groups like that suggest interference between the gas block and rail, or gas tube and upper. Even the worst barrels will normally print under 2".

I've said it elsewhere, Criterion is the best deal going. The one I bought is immaculate inside and has a gas port that looks reamed. I caught it on sale for roughly $300 here: https://ar15discounts.com/products/...08-m118-hybrid-stainless-rifle-length-barrel/

 

[jLorenzo]

Post some pictures of your upper build. Groups like that suggest interference between the gas block and rail, or gas tube and upper. Even the worst barrels will normally print under 2".

I've said it elsewhere, Criterion is the best deal going. The one I bought is immaculate inside and has a gas port that looks reamed. I caught it on sale for roughly $300 here: https://ar15discounts.com/products/...08-m118-hybrid-stainless-rifle-length-barrel/

I checked all that, plenty of room with the handguard. Gas tube it not binding or anything. The bipod was kid of rough and I can tell that large framer gassers are probably the hardest to shoot well. Even still I can shoot pretty well with my SPR. Lots of follow through. One or two of the groups was 2ish" but not even close to consistently.

I did start with the gas block wide open and worked my way back after each 5 round group. Needed to come back a decent amount before I stopped getting ejector smears/burrs.

Remember some of those way out shots were from zeroing the scope. it came off a gun with a 20 moa rail and the windage was like 5 mils off on the new gun.

 

[SolidCopper]

If you’ll humor me, my experience with large frame gassers is that one really has to have their fundamentals dialed in consistently to shoot them well. Also, I discovered my gas gun doesn’t like a bipod. It bounces all over hell and creation and doesn’t group for shit. I chalk this up, partly, to the nature of the bipod/hand guard/barrel nut relationship. Once I started using a bag for a rest and really got my body position and head/eye position correct and consistent, my rifle showed its quality. It could be that none of this applies to you and if it doesn’t then just ignore me.

 

[jLorenzo]

If you’ll humor me, my experience with large frame gassers is that one really has to have their fundamentals dialed in consistently to shoot them well. Also, I discovered my gas gun doesn’t like a bipod. It bounces all over hell and creation and doesn’t group for shit. I chalk this up, partly, to the nature of the bipod/hand guard/barrel nut relationship. Once I started using a bag for a rest and really got my body position and head/eye position correct and consistent, my rifle showed its quality. It could be that none of this applies to you and if it doesn’t then just ignore me.

I'm sure you're right.

 

[jLorenzo]

The Rainier went back, I am going to bite the bullet and go Krieger. Can anyone speak to the difference in the breech and neck length and diameter they offer? I assume shorter is more of a match chamber and longer leaves more room for functioning?

 

[JR1200W3]

RTR .308 Match 18"

craddockprecision.com

 

[NHPiper]

Seekins SP10 6.5CM

S&B PMII 5-25

Sig 7.62Ti

Vortex Impact 4000

L3 CNVD-LR

 

[jLorenzo]

I put a Aero upper and Ballistic advantage barrel together and am getting light primer strikes here and there. Put the heavy spring in the Larue 2 stage, still happens. Most rounds fire but every range trip out of 3 had a few light strikes. New CCI 200s with varget, no issues in other guns.

I have resized brass fired from the chamber and was not able to bump the shoulder with the die touching the shell holder. I also noticed a little bit of soot on the shoulders of some of the rounds. If I rechamber a round that failed to fire, they always fire on the second try. Headspace probably? Its an Aero M5 bcg. Ballistic advantage 18" hbar 308. I need a new bolt or a new barrel if thats the case right?

 

[PappyM3]

I put a Aero upper and Ballistic advantage barrel together and am getting light primer strikes here and there. Put the heavy spring in the Larue 2 stage, still happens. Most rounds fire but every range trip out of 3 had a few light strikes. New CCI 200s with varget, no issues in other guns.

I have resized brass fired from the chamber and was not able to bump the shoulder with the die touching the shell holder. I also noticed a little bit of soot on the shoulders of some of the rounds. If I rechamber a round that failed to fire, they always fire on the second try. Headspace probably? Its an Aero M5 bcg. Ballistic advantage 18" hbar 308. I need a new bolt or a new barrel if thats the case right?

Did you try a new firing pin? Might be ever so slightly on the short end.

 

[NHPiper]

I put a Aero upper and Ballistic advantage barrel together and am getting light primer strikes here and there. Put the heavy spring in the Larue 2 stage, still happens. Most rounds fire but every range trip out of 3 had a few light strikes. New CCI 200s with varget, no issues in other guns.

I have resized brass fired from the chamber and was not able to bump the shoulder with the die touching the shell holder. I also noticed a little bit of soot on the shoulders of some of the rounds. If I rechamber a round that failed to fire, they always fire on the second try. Headspace probably? Its an Aero M5 bcg. Ballistic advantage 18" hbar 308. I need a new bolt or a new barrel if thats the case right?

Grab a set of case chamber gauges and you should be able to verify.

I haven't had good luck with the larue triggers. I have found them very finicky. I have had 2 go full auto on me that got sent back.

Swap in another trigger and see if the same thing happens.

 

[357Max]

Poor-arue build:

This all started when one of you assholes posted a pretty killer clearance sale link for Larue barrels. The 16" 308 8 twist Stealth got my interest since I had a new KGM R30T and some other random large frame parts. The wheels got to turning from there.

Info on receiver sets.

So I'd initially planned to build this as a DPMS style using an Aero M5 upper on a JL Billet ambi lower. For some stupid reason JL Billet doesn't make a high profile upper to go with there lower. The short of it is the Aero upper fits like shit on the JL lower. I kind of went down the rabbit whole from there. Ordered a Bkings matched upper/lower set + 1 upper. The B kings set is the best deal hands down for large frame IMO right now.
The BK Mod-0 thermal upper with the ambi lower was $285 on sale. It fits so well I can hold it upside down without pins. I have also verified the Mod- 0 uppers extension bore is .004 undersized for thermal fit depending on barrel extension. That Thermal fit is uncommon for large frames especially at that price point. The extra BK Mod-0 upper does in fact fit the JL Billet lower much better than the Aero. Lines don't match up very well, but fit is excellent.

In the spirit of this being a Poor-arue build I also ordered an AR10 style Stag receiver set. Decided to go with the Stag set for this.

Build list:

• Stag AR10 receiver set pins included
• Larue Stealth 16" 308 8 twist mid gas made from Atlas shrugged steel
• Hera adjustable gas block with threaded in tube (made in Germany)
• Brownel's low mass carrier
• Rubber city Armory HP bolt & pin
• Battle arms pro ambi selector 45 degree
• Geissele Super charging handle
• Geissele National match trigger
• Wilson Starbust/BCM grip
• Centurion 14" CMR handguard original style
• Magpul enhanced aluminum trigger guard
• Law tactical folder
• Vltor I-mod clubfoot stock & extension
• JP polished carbine buffer spring
• Odin Works adjustable AR10 carbine buffer weight, set to 4.65 oz
• LWRC skirmish BUIS
• KGM R30T
• Vortex PST 2 mil 2-10 in Midwest QD mount
• Larue mags

Upper was loose extension fit like the Aero. The extension was also out of square. Trued the face and used 2 full wraps of ss shim stock on the extension (.004"). Used a trigger shims .005 for front take down pin. Used the stag receiver tension screw set for firm drag on the rear pin. Machined the Stag lower for a PDQ ambi bolt catch as I'd been wanting to try the large frame version. I had to machine the notch in the PDQ .060 wider towards the magwell side.

See that little plastic piece next to the screwdriver, I'll get to that in a minute.

Machined .040 off the bottom of the Hera gas block to give more clearance to the spine in the bottom of the CMR handguard. Those Centurion rails are rigid & I like them, but they don't have much clearance for gas blocks.

I've been using either Dark hour defense or PWS extensions with the extended tail to support the carrier. I've done some rudimentary testing on small frames comparing these to a std extension. When you close the receiver using the extended tail extension I can see the back of the carrier lift as it closes. This does not happen with std extensions. I'm a proponent of squaring the bolts up best as possible. It was bugging me a little that with the Law folder, there is no rear carrier support possible with the above mentioned extensions. This is where that little plastic piece comes into play.
Figured why not. So I machined that from Ultem (high temp, strong, oil resistant plastic). It slides down into the un-used buffer detant hole in the receiver. That little dog point set screw pictured above screws in from the back of the receiver to lock it in. Now my carrier has support with the law folder.
Shown below mocked up with a std extension checking alignment. Does it matter? Hell if I know.

Got it to the range just to break in and get some brass formed to chamber. Had to make 1 adjustment to gas block closing 1/4 turn.
Ran 4 different loads Noma Tac 150FMJ, Old milsurp Sig 58 Patronen FMJ magnetic, Southern munitions loaded with 155 Hornady HPBT, & of coarse FGMM 168.
The Norma Tac & the FGMM are within 20fps and both shot the best. Norma just over moa & FGMM just under moa.
Then took the FGMM out to 500 x 5 on steel. Very pleased with how it turned out. Cycled all the ammo without a hickup.
Hand loads next.
As a side note: I really like how the Stag receiver lines appear to align with the hand-guard (last picture).

5 @ 500 FGMM

 

[jLorenzo]

Poor-arue build:

This all started when one of you assholes posted a pretty killer clearance sale link for Larue barrels. The 16" 308 8 twist Stealth got my interest since I had a new KGM R30T and some other random large frame parts. The wheels got to turning from there.

Info on receiver sets.

So I'd initially planned to build this as a DPMS style using an Aero M5 upper on a JL Billet ambi lower. For some stupid reason JL Billet doesn't make a high profile upper to go with there lower. The short of it is the Aero upper fits like shit on the JL lower. I kind of went down the rabbit whole from there. Ordered a Bkings matched upper/lower set + 1 upper. The B kings set is the best deal hands down for large frame IMO right now.
The BK Mod-0 thermal upper with the ambi lower was $285 on sale. It fits so well I can hold it upside down without pins. I have also verified the Mod- 0 uppers extension bore is .004 undersized for thermal fit depending on barrel extension. That Thermal fit is uncommon for large frames especially at that price point. The extra BK Mod-0 upper does in fact fit the JL Billet lower much better than the Aero. Lines don't match up very well, but fit is excellent.
View attachment 8438757

In the spirit of this being a Poor-arue build I also ordered an AR10 style Stag receiver set. Decided to go with the Stag set for this.

Build list:

• Stag AR10 receiver set pins included
• Larue Stealth 16" 308 8 twist mid gas made from Atlas shrugged steel
• Hera adjustable gas block with threaded in tube (made in Germany)
• Brownel's low mass carrier
• Rubber city Armory HP bolt & pin
• Battle arms pro ambi selector 45 degree
• Geissele Super charging handle
• Geissele National match trigger
• Wilson Starbust/BCM grip
• Centurion 14" CMR handguard original style
• Magpul enhanced aluminum trigger guard
• Law tactical folder
• Vltor I-mod clubfoot stock & extension
• JP polished carbine buffer spring
• Odin Works adjustable AR10 carbine buffer weight, set to 4.65 oz
• LWRC skirmish BUIS
• KGM R30T
• Vortex PST 2 mil 2-10 in Midwest QD mount
• Larue mags

Upper was loose extension fit like the Aero. The extension was also out of square. Trued the face and used 2 full wraps of ss shim stock on the extension (.004"). Used a trigger shims .005 for front take down pin. Used the stag receiver tension screw set for firm drag on the rear pin. Machined the Stag lower for a PDQ ambi bolt catch as I'd been wanting to try the large frame version. I had to machine the notch in the PDQ .060 wider towards the magwell side.
View attachment 8438771See that little plastic piece next to the screwdriver, I'll get to that in a minute.

Machined .040 off the bottom of the Hera gas block to give more clearance to the spine in the bottom of the CMR handguard. Those Centurion rails are rigid & I like them, but they don't have much clearance for gas blocks.
View attachment 8438806

I've been using either Dark hour defense or PWS extensions with the extended tail to support the carrier. I've done some rudimentary testing on small frames comparing these to a std extension. When you close the receiver using the extended tail extension I can see the back of the carrier lift as it closes. This does not happen with std extensions. I'm a proponent of squaring the bolts up best as possible. It was bugging me a little that with the Law folder, there is no rear carrier support possible with the above mentioned extensions. This is where that little plastic piece comes into play.
Figured why not. So I machined that from Ultem (high temp, strong, oil resistant plastic). It slides down into the un-used buffer detant hole in the receiver. That little dog point set screw pictured above screws in from the back of the receiver to lock it in. Now my carrier has support with the law folder.
Shown below mocked up with a std extension checking alignment. Does it matter? Hell if I know.
View attachment 8438835

Got it to the range just to break in and get some brass formed to chamber. Had to make 1 adjustment to gas block closing 1/4 turn.
Ran 4 different loads Noma Tac 150FMJ, Old milsurp Sig 58 Patronen FMJ magnetic, Southern munitions loaded with 155 Hornady HPBT, & of coarse FGMM 168.
The Norma Tac & the FGMM are within 20fps and both shot the best. Norma just over moa & FGMM just under moa.
Then took the FGMM out to 500 x 5 on steel. Very pleased with how it turned out. Cycled all the ammo without a hickup.
Hand loads next.
As a side note: I really like how the Stag receiver lines appear to align with the hand-guard (last picture).
View attachment 8438848
5 @ 500 FGMM
View attachment 8438849
View attachment 8438850
View attachment 8438851

How do you like that scope?

 

[357Max]

How do you like that scope?

I like it a lot. Had it on several guns. Nice having parallax adjustment with the 2-10.

 

[stormhammer]

I'm one of those who bought the purple Aero anodized set. Still a work in progress but as it stands.

Aero M5E1 upper, lower, handguard, charging handle, tube.
ADM purple end plate
FCD "Purple Knight" castle nut
Aero LPK + trigger
Cryptic Coatings "Dragons Breath" BCG
Ballistic Advantage 16" 308 barrel ( Schulyer Arms had a sale for $75 on them. Hard to pass it up ) - still debating on maybe doing a 14.5-16" 6.5CM
Rearden "Black Rainbow" Type B muzzle device
Armament Technology SAI 6 LPVO with a Reptilia AUS mount

Still needs a buffer spring/weight, and a gas block/tube, and then to actually assemble/torque it down. Threw it together briefly to take a photo with a Tessa Blue Geissele Super Duty I picked up

 

[Jdowns0415]

I'm one of those who bought the purple Aero anodized set. Still a work in progress but as it stands.

Aero M5E1 upper, lower, handguard, charging handle, tube.
ADM purple end plate
FCD "Purple Knight" castle nut
Aero LPK + trigger
Cryptic Coatings "Dragons Breath" BCG
Ballistic Advantage 16" 308 barrel ( Schulyer Arms had a sale for $75 on them. Hard to pass it up ) - still debating on maybe doing a 14.5-16" 6.5CM
Rearden "Black Rainbow" Type B muzzle device
Armament Technology SAI 6 LPVO with a Reptilia AUS mount

Still needs a buffer spring/weight, and a gas block/tube, and then to actually assemble/torque it down. Threw it together briefly to take a photo with a Tessa Blue Geissele Super Duty I picked up

View attachment 8439881

PURPLE RAIN!!!

 

[Jdowns0415]

Updated photo. Got a rifle tube and 308 PRS Gen 2 stock, the next question is which criterion barrel to replace the 18 inch one with. I was thinking 22 inch stainless. Also swapping out the SCS spring with a regular spring and buffer so I don’t beat my brass to death. My superlative arms gas block doesn’t really seem to shut gas off no matter how much I close it so might get a Non adjustable as well…decisions decisions.

 

[mrtoyz]

Updated photo. Got a rifle tube and 308 PRS Gen 2 stock, the next question is which criterion barrel to replace the 18 inch one with. I was thinking 22 inch stainless. Also swapping out the SCS spring with a regular spring and buffer so I don’t beat my brass to death. My superlative arms gas block doesn’t really seem to shut gas off no matter how much I close it so might get a Non adjustable as well…decisions decisions.

That’s odd about your gas block. Been very happy with mine. I’d definitely reach out to their CS, I found them to be very helpful.

 

[Cascade Hemi]

If you take an uninstalled SA gas block and turn it over, you can see the needle valve obstruct the gas port as you screw it in. The needle screw is replaceable if it's damaged or defective. The same is also true of SLR, Aero, and all of the rest of the needle vale AGB's on the market.