re: Official AR-15 thread

quote:

---

rungunz

---

are you in the industry? or just a hobbyist? you've been all over the board the past few days

quote:

---

SS barrels have a shorter lifespan than nitride or chrome lined. I built an upper with a stainless barrel with a 12 power optic because I use it for shooting paper. If you are mag dumping and plan on throwing a lot of rounds through it I wouldn't get a SS barrel.

---

I can't imagine why anyone would get a SS barrel unless they were planning on using it for competition.

quote:

---

SS barrels have a shorter lifespan than nitride or chrome lined.

---

I don't know why anyone would treat the bore of a SS barrel.

quote:

---

Colt, the original owner of the M16 FOW TDP...

14.5" Colt M4/6921: 0.062"

10.3" Colt Mk18: 0.070"

Here is the Mk18 .pdf put out by NSW-Crane:

www.dtic.mil/ndia/2003smallarms/john.ppt

Manufacturer don't disclose their GP diameter to the public, but they can be measured with a pin gauge. It's not hard to tell when a barrel is over-gassed. Some manufacturers are ported more appropriately than others.

---

Great you found a manufacturer's power point. Cite the military specification. for instance, MIL-B-11595E is the material specification for small arms barrel steel.

What is the milspec gas port diameter for the 16" 5.56, 10.5 5.56, 18" .625 journal rifle length 5.56, any .300BLK, 6.5 grendel, 6.8 SPC, etc.? Thanks for the tip on the pin gauge.

quote:

---

Manufacturer don't disclose their GP diameter to the public

---

Some do

quote:

---

I listed the gas port diameters to two commonly fielded Colt weapons. You know, the company that owns the TDP...

From this data, one can infer what should be an efficient range for gas port sizes for barrels within 10.3" - 14.5".

---

For a manufacturer producing barrels where the ammo used is known. Aftermarket barrel producers do not have the luxury of knowing exactly what ammo you'll be using and at what pressure ranges so they overgas them to function with the widest variety. As you've probably realized though your googling trying to prove me wrong the military does not make specifications for gas port diameter. Especially in barrel lengths and profiles most commonly used in the AR-15 (consumer) market. Making an 'inference' based on one manufacturer's port size for 2 barrels does not equal a spec. That's an opinion which varies from manufacturer to manufacturer based on what they think will reliably cycle the ammunition most widely used/available in the US market.

quote:

---

I don't know why you're so opposed to accepting this data.

---

Because you show up regurgitating ARFCOM BS as fact, and I'm petty, so I'm calling you on it.

To quote the great Clames:

"I'm right, you're wrong and there's nothing you can do about it."

Anyone happen to have a good link with info on a step by step of how to go about filing for a SBR tax stamp for a rookie? I'd like to apply for one. Also, any idea on a turnaround timeframe now that ATF has been bombarded with forms due to the recent changes?

quote:

---

quote:
For a manufacturer producing barrels where the ammo used is known. Aftermarket barrel producers do not have the luxury of knowing exactly what ammo you'll be using and at what pressure ranges so they overgas them to function with the widest variety. As you've probably realized though your googling trying to prove me wrong the military does not make specifications for gas port diameter. Especially in barrel lengths and profiles most commonly used in the AR-15 (consumer) market. Making an 'inference' based on one manufacturer's port size for 2 barrels does not equal a spec. That's an opinion which varies from manufacturer to manufacturer based on what they think will reliably cycle the ammunition most widely used/available in the US market.


Because you show up regurgitating ARFCOM BS as fact, and I'm petty, so I'm calling you on it.

To quote the great Clames:

"I'm right, you're wrong and there's nothing you can do about it."

---

Those are some bold assumptions.

It's not "ARFCOM BS".

TDP = Colt

I'm well aware of why manufacturers over-gas. If it wasn't for everyone shooting weak .223, I could still get a BCM or KAC tuned to run 5.56.

REGARDLESS, there are gas port diameters (+/- adj gas block) that allow smoother function.

We agree that most commercial ports are over-gassed - great. Can we move on?

quote:

---

Aftermarket barrel producers do not have the luxury of knowing exactly what ammo you'll be using and at what pressure ranges so they overgas them to function with the widest variety. As you've probably realized though your googling trying to prove me wrong the military does not make specifications for gas port diameter. Especially in barrel lengths and profiles most commonly used in the AR-15 (consumer) market.

---

Throw in the fact that a military contractor knows - for a fact - that the customer will be using 2 - and only 2 - receiver extension/buffer/spring combinations and your point is even more well made.

But, what the frick do you know, Prop - you've only built the stupid things from a myriad of mismatched parts and made them go bang, right?

quote:

---

Because you show up regurgitating ARFCOM BS as fact, and I'm petty, so I'm calling you on it.

---

I'm going to admit, this made me chuckle, IRL. And I don't know this poster, just showed up the past couple of days. Clearly some sort of Colt "queer" (NTTAWWT).

quote:

---

"I'm right, you're wrong and there's nothing you can do about it."

---

(This feels like an OT thread, suddenly. That's not a good thing.)

I just wanna know if I can get away with a $25 gas block or if the $55 gas block is a good investment.

I am quickly becoming overwhelmed with all the available parts.

I liked walking into the store yesterday and getting what I needed.

I need to find all my upper parts.........and since this is my first one I want to gear it up. Optics.....flash lights and all that shite