Need advice on matching rifle upper and carbine lower

[charliebrown1999]

I have always wanted have an Aero Precision lower and upper. I prefer Aero Precision M4E1 complete upper (well almost complete since it does not include a bcg or charging handle) with 18 inch fluted barrel and rifle length gas system. I have been a CA resident for over 80 years therefore the complete lower I that I will order has to be CA compliant. It will be the M4E1 Featureless lower with Magpul fixed carbine stock.
My concern is that the several buyers have stated that the barrel gas port is only .0935 and the gun will not run. They have drilled the port to .0985. So, it appears that it maybe under gassed. This under gassed condition will only be worst when you consider that the carbine stock will most probably have a heavy buffer and heavy buffer spring.
So, what is your considered opinion on replacing the heavy carbine buffer for one that weighs about 3.2oz and replacing the buffer spring with a reduced power spring???? I am over 80 years old, fingers and hands are a little shaky and do not have the correct drill or bits to enlarge the port. So, I am hoping the gun will run with the light buffer and spring. What do you all think??

 

[sinister]

It'll work and shoot, no problem. I'm finishing one up very close to what you're doing (18" heavy barrel, no flutes).

Use a standard and NOT a heavy spring. Keep the heavy buffer.

Good luck, and good shooting!

 

[charliebrown1999]

It'll work and shoot, no problem. I'm finishing one up very close to what you're doing (18" heavy barrel, no flutes).

Use a standard and NOT a heavy spring. Keep the heavy buffer.

Good luck, and good shooting!

The 18inch stainless fluted bbl. is about 6oz lighter than the non-fluted bbl. May I ask why you want the heavier bbl? Could it be that the non-fluted heavier bbl. heat up much slower and therefore be more accurate after 80 or 100rds?

 

[sinister]

I go through barrels quickly. The additional cost for fluting doesn't make sense for my break-even math.

 

[JohnCarter17]

I go through barrels quickly. The additional cost for fluting doesn't make sense for my break-even math.

Envious of your ammo budget.

 

[charliebrown1999]

I go through barrels quickly. The additional cost for fluting doesn't make sense for my break-even math.

Thank you. I wish my ammo budget would allow me to shoot-out a barrel.

 

[Trumpster24]

I go through barrels quickly. The additional cost for fluting doesn't make sense for my break-even math.

Good for you, pressin 74 myself. Sorry to hear you're still in CA. Bailed to WY in 21, WY has unlicensed CC. and scant crime.
Colts 20" rifle barrel for the M16A1 is 0.092"-93" Most manufactures port rifle barrels 18"-20" around 0.070".
So 092" can be overgassed to start with. Recoil is directly proportional to port size.
Google, AR gas port sizes responses; several dozen manufactures and hundreds of barrels their port sizes listed.

Ideally you want the greatest amount of energy propelling the bullet not overgassing the system.

Thermal heat videos of the ARs show them getting hotter until reaching their "cook points" *
Fluting a barrel for heat dissipation can be folly considering the scale or purpose for which the firearm is designed for.
Most people can't carry enough ammo to heat up a gun making a fluted barrel is practical.
Weight advantage of only 6oz is about equal to a dozen rounds!
WHO is going into a "tactical" situation? $$
Remember we only need 30 round mags to protect ourselves against bad actors with 30 rd mags.

* semi auto firearm is so hot its ammo detonates before the breach is locked .
A disaster I have been through myself.
Carry on sir.

 

[clcustom1911]

Good for you, pressin 74 myself. Sorry to hear you're still in CA. Bailed to WY in 21, WY has unlicensed CC. and scant crime.
Colts 20" rifle barrel for the M16A1 is 0.092"-93" Most manufactures port around 0.070" so 092" is overgassed to start with and recoil is directly proportional to port size. Google AR port sizes;


Ideally you want the greatest amount of energy propelling the bullet not overgassing the system.

Thermal heat videos of the ARs getting hotter until reaching the "cook point" * reveal fluting a barrel for heat dissipation can be folly considering the scale or purpose for which the firearm is designed for. Most people can't carry enough ammo to heat up a gun where a fluted barrel is necessary. For weight savings a 6 oz difference in weight is about equal to a dozen rounds. So much advertising gimmickry in gun parts. WHO is going into a "tactical" situation? $$
Remember we only need 30 round mags to protect ourselves against bad actors with 30 rd mags.
* semi auto firearm is so hot its ammo detonates before the breach is locked . A disaster I have been through myself.
Carry on sir.

According to your chart, ports at the "rifle" length and 18-20" long barrels chambered in 5.56/223 are always in the 0.08xx - 0.09xx" size.

Your assertion the OP's gas port of a rifle length gas system in an 18" bbl is incorrect according to your own data you posted.

0.06x - 0.07x" size gas ports are for carbine length gas ports with shorter barrel length based on your chart provided.

 

[msgriff]

snip...

* semi auto firearm is so hot its ammo detonates before the breach is locked .
A disaster I have been through myself.
Carry on sir.

Can you provide some details on when this happened to you, such as the firearm in which it occurred and under what circumstances.

 

[clcustom1911]

Can you provide some details on when this happened to you, such as the firearm in which it occurred and under what circumstances.

*popcorn sounds intensify*

 

[Jsp556]

18” rifle gas barrels ported @ .093 work just fine unless you’re shooting lower pressure ammo.