AR-15 build info.

[BradMacc82]

I was hoping someone would write a section on flash suppressors. I have everything but a flash suppressor. I want to buy a yhm flash suppressor at Joebobs but it doesn't say what the lengths are. I have a 14.5 barrel and need the right length. Can someone help please?

Any of the Phantom series should put you at 16.1" OAL when installed and pinned/welded.

Although, you could just spend a touch more and buy a suppressor mount - puts you in the happy spot length-wise, and gives you the option of running a can at a later date. They also do well with flash suppressing.


ETA: The Phantom 5C2 should definitely get you where you need to be if a mount isn't an option.

 

[huesmann]

Isn't even a regular A2 flash hider long enough to bring a 14.5" bbl over 16"?

 

[huesmann]

I intend to use a flip-up sight until I can afford optics later down the road.

If you're running a free-float forearm with a rail on top, that's just fine.

 

[BradMacc82]

Isn't even a regular A2 flash hider long enough to bring a 14.5" bbl over 16"?

I'd have to check the length, but I want to say it'll be just under 16" with an A2 mounted.


Where's Chad..., he'd know for certain.

 

[clandestine]

I'd have to check the length, but I want to say it'll be just under 16" with an A2 mounted.


Where's Chad..., he'd know for certain.

Correct, a regular A2 will not give you the necessary length on a 14.5" Barrel when Pinned and Welded. There are extended A2's available.

 

[lauderman]

If you're running a free-float forearm with a rail on top, that's just fine.

I'm excited to get started on these two builds, but know that I'm going to run into frustration finding some of the parts like BCG and barrels I want.

 

[lauderman]

Just trying to be certain but the only difference between a 5.56 and 7.62 is the barrel and bolt correct? Or is the entire BCG different?

 

[lauderman]

I want YHM barrels for both and they have the 7.62 in stock, but sold out of 5.56. Anyone know where to find one. My plan is to acquire all the parts for both builds while I wait the 60-90 day ND.

 

[Bernie]

I just purchased two 80% lowers from CNC80.COM. They are provided anodized but with extra hardware. There are addtinal drilled and tapped holes under the lower and you are provided with two set screws that appear to be to do something with the trigger pin and also the take down pin. I am sure that the firm that acutally makes these is not CNC80, do you know the orighinal maker and also any written info on how to install and adjust these extra set screws?

 

[Bernie]

Yes, the lowers, the uppers, BCG, magazines are totallu different between 5.56 and 7.62 (308 correct?). And due to their being less of the 7.62 stuff made, they are a lotmore expensive than stuff for the 5.56........

 

[huesmann]

Just trying to be certain but the only difference between a 5.56 and 7.62 is the barrel and bolt correct? Or is the entire BCG different?

Are you talking 7.62x39 (AK) or 7.62x51 (NATO)?

 

[lauderman]

Are you talking 7.62x39 (AK) or 7.62x51 (NATO)?

7.62x51 NATO

 

[Sticky]

I just purchased two 80% lowers from CNC80.COM. They are provided anodized but with extra hardware. There are addtinal drilled and tapped holes under the lower and you are provided with two set screws that appear to be to do something with the trigger pin and also the take down pin. I am sure that the firm that acutally makes these is not CNC80, do you know the orighinal maker and also any written info on how to install and adjust these extra set screws?

Is one about a 1/4" dia and located just behind the grip screw hole and cuts into the rear of the FCG pocket? That is used to take out any play between the upper and the lower. I do that on my lowers when I finish them. I also use a nylon tipped setscrew for that hole. Basically it allows you to put a little pressure on the underside of the rear takedown lug on the upper when mated to the lower. If you have a little freeplay in the fit, that will remove it..

The other, I suspect is a trigger freeplay/creep adjustment screw. I do mine differently, drilling and tapping a bolt for the grip screw and inserting a small setscrew in there.

 

[Sticky]

Is one about a 1/4" dia and located just behind the grip screw hole and cuts into the rear of the FCG pocket? That is used to take out any play between the upper and the lower. I do that on my lowers when I finish them. I also use a nylon tipped setscrew for that hole. Basically it allows you to put a little pressure on the underside of the rear takedown lug on the upper when mated to the lower. If you have a little freeplay in the fit, that will remove it..

The other, I suspect is a trigger freeplay/creep adjustment screw. I do mine differently, drilling and tapping a bolt for the grip screw and inserting a small setscrew in there.

This is where I put the first hole.. I don't use another hole, just modify the grip screw..

 

[Sticky]

I just purchased two 80% lowers from CNC80.COM. They are provided anodized but with extra hardware. There are addtinal drilled and tapped holes under the lower and you are provided with two set screws that appear to be to do something with the trigger pin and also the take down pin. I am sure that the firm that acutally makes these is not CNC80, do you know the orighinal maker and also any written info on how to install and adjust these extra set screws?

I just looked at their site.. the upper tensioning screw is probably the same way I do mine, the other screw is the reset adjustment screw. My method does not really affect the reset as much as remove the creep.. Similar though. I like the tapped bolt catch hole and rear takedown pin hole.. nice adders. I may do this on my next one..

 

[huesmann]

7.62x51 NATO

Then no, the NATO round is too long to fit in a standard AR-15 mag well, so you need a .308-specific lower and upper.

 

[lauderman]

Then no, the NATO round is too long to fit in a standard AR-15 mag well, so you need a .308-specific lower and upper.

Sorry i meant to say 7.62x39

 

[Shoobedoo]

Is one about a 1/4" dia and located just behind the grip screw hole and cuts into the rear of the FCG pocket? That is used to take out any play between the upper and the lower. I do that on my lowers when I finish them. I also use a nylon tipped setscrew for that hole. Basically it allows you to put a little pressure on the underside of the rear takedown lug on the upper when mated to the lower. If you have a little freeplay in the fit, that will remove it...

The nylon set screw is a great idea, my 80% lower came with a steel screw but I think I'll replace that with a nylon.

Not that I'll ever need it, all my uppers and lowers fit together rock solid with no perceptible play in any of them, but it's still nice to have the capability if needed.

 

[Sticky]

The nylon set screw is a great idea, my 80% lower came with a steel screw but I think I'll replace that with a nylon.

Not that I'll ever need it, all my uppers and lowers fit together rock solid with no perceptible play in any of them, but it's still nice to have the capability if needed.

I have one build that had a little play in the fit and I found that if you tighten it against the upper's lug, you have to be careful how tight you take it to allow you to remove and reinstall the takedown pin. Unless you don't take your gun down, then you can jam it tight, but I take mine down to clean after every couple of rounds of shooting, even if it's just a few shots at the varmints over a couple weekends.

That is the only build I have even used the screw for, the others were just fine..

 

[Shoobedoo]

I have one build that had a little play in the fit and I found that if you tighten it against the upper's lug, you have to be careful how tight you take it to allow you to remove and reinstall the takedown pin. Unless you don't take your gun down, then you can jam it tight, but I take mine down to clean after every couple of rounds of shooting, even if it's just a few shots at the varmints over a couple weekends.

That is the only build I have even used the screw for, the others were just fine..

I understand what you're saying. One thing you could do is just back out the screw a tiny bit before taking it down, then screw it back in a bit when you re-assemble it. The thing that concerned me about the steel screw on mine is I believe it would have a tendency to "bite" in to the upper receiver lug, and over time that would probably cause some wear at the contact point on the upper. You won't ever have that problem with a nylon screw. Again, a great idea and thank you for mentioning it.