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So now the LR .308


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With the AR15 underway I have some time to begin what I started out coming here for in the first place...building an LR style .308. Finished up the milling on the lower and dropped in the CMMG TCG. And right off the bat things go awry. But before I get there heres some info: I'm using the Easy Jig Gen 2. When sliding in pins and tightening down plates it fought the entire way. It references on the front pin, buffer tube, and rear pin. Needless to say everything had to be in place before it could be fully tightened down. This was not the case with a AR15 lower. Note to self...gotta keep this in mind for the next one.  Being my second, the milling went flawless. Dropped in the trigger and pinned it. Dropped in the hammer and pinned it and now the fun starts. Looking down in the TCG pocket the trigger is canted to the right side of the well 😫 My first thought is a wasted lower due hole misalignment. ARGH. Function check the trigger anyway, fires, fires, and on reset check the hammer lets go and flies forward. The feel of this trigger is like its dragging on 40 grit paper for 100ft and then lets go. When I looking at the parts prior the assembly the amount of machine marks would make you sad. Fawk it lets push on... In goes the safety. NOT. Disassemble the TCG, put the safety in, put trigger in, put hammer in. Just no love on this lower. Safety so tight its non-functional. Disassemble and reassemble. No love. Looks as if the second shelf of milling (B) on these 80% lowers just doesn't take enough of the floor. Same results, just not as bad, on my AR15.

Next steps - Full disassembly. Re-mount in the jig and take some more clearance off the floor for extra space to allow for the trigger to move down to allow safety to fit in easier. I'll use the trigger pins to see if I can measure a distance between to points to see if there is a gross issue in terms of pin alignment. Maybe I just got a lemon TCG? This is my first foray into CMMG parts and I'm not impressed yet. The Anderson parts in the AR15 out do my Colt LE tenfold. Smooth, a bit long, but clean as hell. No grit feel anywhere.

QUESTION - When assembling the lower TCG, which side do you start the pins from (left or right?) An what is the pin orientation? (milled slot first to or non-slot side first?)

More saga and pics later today.

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When you say "smooth" end first, it sounds like the chamfered and then the ring, followed by a second ring in the middle and then the blank end following...? This is the way the AR15 went together.

I like the jig I have but when leaning to "more is better", the thickness of the 5D jig seems to be head and tails above all. Let me see how things turn out on this lower and I may have a different opinion. It's a damned good jig and things are rock solid when bolted in. But if I can't get repeatable results...it will end up on the shelf. Stay tuned.

In this pic you can see how the trigger is far to the right, cocked or un-cocked t. Could be me, my jig, my pins, or my TCG. Taking apart to find out now. I will measure. Reassemble. and report back. 


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6 hours ago, RedRiverII said:


Done half a dozen or so lowers with the 5D, .40 to 308, all shooters. There are a few tricks to learn but I would recommend. If you decide get one give a shout before starting, I could save you some "Oh $hit" moments. 

2 hours ago, PaddyMac said:

In this pic you can see how the trigger is far to the right,

Photo is kind of blurry down in the pocket, but something doesn't look quite right, like your step "1" or "A" isn't deep enough or not in the right place.  Should be flush with the bottom of the takedown pin pocket. Also, hard to tell but step "2" or "B" doesn't look far enough to the rear. Another thing the section between the FCG and the takedown pocket looks too narrow. 




Edited by Albroswift
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19 hours ago, Albroswift said:

@PaddyMac One other thing, looks like your hammer spring possibly is between the trigger shaft and the receiver housing, shoving the trigger to the right. Should be on top of the trigger shaft in the cut away and in the grove of the trigger pin. Blurry, could be wrong.

I'll be quiet now...

Yep. Thats exactly how I have it. Will disassemble and get a good visual on what the hell I'm doing wrong.

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OK... What I really wanted to do was stick the lower back in the jig and check tolerances but I said fawk it. I disassembled the TCG several times and basically changed the spring orientation a bit to ride in the trigger saddles / cutouts better. This is bullpoopy machining techniques because it looks cocked and like ass. I'm a perfectionist to a point, at least with firearms. Albroswift was correct on his assumptions but this POS still looks whacked. Anyway - after 4 removals and re-installs the SOB cocks, has trigger reset and passes function checks! Woot! I have one more CMMG lower parts kit but didn't break it out to see if its different. I cleaned up the safety holes and now it functions nicely. I have a feeling that my jig is like a chick and I need to learn what this bitch wants. One thing I know for sure - if you use this jig make your second pass 1 notch lower than what it calls for. This will lower the floor of the well and give you a few thous of breathing room in the trigger area. 

Initial thoughts... The Easy Jig Gen 2 may not be the best for .308's. I have another lower from a different place and I'm gonna run through it next. If its tight and requires all bolts to be synched simultaneously I'm stopping. Shite ain't right. If it bolts up nice and square -  cool beans

As for the CMMG lower kit. Not impressed. Piss poor machining you can see with the naked eye and a fingernail. Lot's o jack for a box of ass. The Anderson AR15 lower kit was nice. Match grade - NO. But the CMMG kit is the ultimate lawyer, government trigger. 8-9 lbs at least (I will measure), feels like you are dragging it on concrete for 100 yards. When it breaks it scares the fawk out of you because you had no idea where in the trail of tears you were...50 yd line maybe?... trying to hold it on zero. So yeah, it breaks pretty clean if you have the nerves to take it that far.

Putting in the front pin, spring and detent in I was so happy but didn't check the groove orientation before I tried it out. Yeah, spring and pin took off like a fawking rocket landing in parts of the gun room unknown. Heard one of them land but alas...eyes aren't good enough to find them.

Just another night on the bench. Thanks all.

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On 3/15/2020 at 12:34 PM, RedRiverII said:

Would you recommend the jig you have or do you think the 5DTactical might be better.  I'm considering buying a set up,  thanks in advance for your consideration.

Give me another 1 or 2 builds. I've got a few stacked up both 15 and 308. They will happen in short order. Chat with Albroswift. He's done several successful builds with the 5D. I like the Easy Jig set up with less fasteners and hex keys. 5D uses tons of fasters that are Phillips 🤨  But... 5D has 1.5in side plates and the Easy Jig is 1/2 in. I'll let you know on the next 308 build.


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Anderson ain't bad for the price for a mil spec FCG  lately tried the LaRue 2 stage recommended around here and the Rise Armament  single stage drop in also recommended on the trigger thread, both great FCGs for under $100.00 Either one hundred times better then mill spec. 

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1 minute ago, PaddyMac said:

5D uses tons of fasters that are Phillips

Correct. Not keen on the phillips but I guess if I really hated them I would swap them out. They are durable enough to use the impact driver on them though. One thing about the 5D, first job came out perfect, one pass. Second one near perfect, little keyholing on the trigger hole (You can see it on the second photo above) wasn't hanging on tight enough when I hit the switch. Chipped a tooth on the mill bit 1/2 way through the 3rd job, wasn't hanging on tight enough a little over confident or something and it jumped a little. Ordered a replacement bit and a complete bit+ holder (What 5D calls the Easymill) for a quick change spare last time they had a sale. Every hole lined up perfectly and every FCG fit and functioned first time installed. Really good directions with the jig. Every lower went right into a carbine or pistol and never an issue. 

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10 hours ago, Albroswift said:

Anderson ain't bad for the price for a mil spec FCG  lately tried the LaRue 2 stage recommended around here and the Rise Armament  single stage drop in also recommended on the trigger thread, both great FCGs for under $100.00 Either one hundred times better then mill spec. 

When googling my problems yesterday I ran into the Rise Armament trigger on a trigger comparison video with all of the big names. Price and performance blew everyone away. Haven't looked at LaRue yet but I never see them getting a bad rap.With you saying 100 times better than mil spec, I'm sold.


3 hours ago, RedRiverII said:

Thank you to @PaddyMac and @Albroswift  I guess it's easy enough to buy hex screws,  and I did notice the beefy plates.  Waiting is expensive right now,  ammo for instance is flying out the door following the panicked.

No Problem. Albroswift says the screws are tough and can handle an impact driver. I'd use them until I buggered 1 or 2 and swap them out. But he's been through several builds so I'd expect that's way down the road.

10 hours ago, Albroswift said:

Wasn't hanging on tight enough when I hit the switch. Chipped a tooth on the mill bit 1/2 way through the 3rd job

😂😁😂  Pretty scary chit I know!! Your only talking about 1/32 into a pilot hole. Easy to get cocked and not notice. I rock the router back and forth to make sure I'm there and then try and hold on to the router with both hands when I hit the "go" button. Always a "pucker" moment. My router has a slow "soft start" cycle (2-3 seconds) until it hits full song (25,000 RPM or so). Even so...if you're not ready there's not enough time to turn things off before the damage begins. Sorry to hear.

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22 hours ago, PaddyMac said:

Even so...if you're not ready there's not enough time to turn things off before the damage begins. Sorry to hear

Part of the learning curve. My router has soft start, and I'm running both that and the vacuum off a foot switch. Still, got to hang on each and every time! No excuse.

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milling a deep pocket into aluminum, with a hand held router, even guided by a jig is maybe one of the more demanding machining operations ever conceived :-). Add into there the fact that many are using cutting tools designed to work well in rigid cnc machines and it gets even more amazing that it actually works out decent :-).



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Posted this a while back on another forum, 5D costs. Get all in for around $400 if you wait for a sale. 

5D pro Jig $200
Tool Kit $55 (3 drill bits and the ready mill)
308 upgrade $60
Dewalt router $120
$435 including the 308 and the recommended router.

Since then I bought a second ready mill and an additional replacement bit. The drill bits they supply are good quality, last 3-4 lowers before starting to dull. The anodizing is really hard on them, if you did raw I'm sure they would last for a long time. Cobalt bits are what I am using now. The end mill in the ready mill is heat installed so bought a complete second ready mill in case I chip a tooth or otherwise damage the bit in the middle of a job  I don't have to get out the torch. 

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  • 1 month later...

Back at it. So I ordered this from Aero Precision:


18" SS fluted upper with rifle gas, M-LOK. FINALLY the FedEx man brought it to my door 2 days ago and the wife immediately sanitized the box. Can't be too safe ya know. I think she's just trying to keep me alive because I do OK for us. Oh well. Brought my finished Cerro 80% lower from the gun room to the kitchen and tried it on for size. Guess what...? No dice  😒   Seems like this is the way things go when you go the 80% route 😢.  Well I don't think its my machining skills this time. Front takedown pin - no problem. Rear takedown pin is a no-go. Tried rear pin first and can get partially through but not the full length. Tight as hell.

My plan is to take it to the gun room with good light and magnification to figure out where it's snagged up. Prolly whip out the vernier calipers and take some measurements as well. I have other 80% lowers from other manufacturers that I'm going to test fit as well. I've got a pair of extra pins to help out.

On a side note - I still need a BCG, rifle stock and buffer tube, and sights. Can anyone suggest a BCG based on the quality of my upper. I'm thinking Toolcraft. I'm gonna call Heavy Buffers for the tube, spring, and buffer. I'd get an A2 style stock but everyone complains about build quality and color. I may just go with a Magpul MOE fixed stock. I have a set of .308 go no-gauges on order and should have in a week or so. 

Pics and build stories to follow.

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