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RWH24
10-09-13, 00:58
PSA 16" middy CHF ULW 1:7 CL & FSB...I believe it is an FN CHF barrel.

What is the gas port size? Anybody know, before I knock the FSB pins out?

http://pic20.picturetrail.com/VOL1321/4777050/24426566/407719888.jpg

http://palmettostatearmory.com/index.php/ar-15-05/complete-uppers/16/psa-16-ulw-hammer-forged-stripped-upper-without-bcg-or-charging-handle.html

Thank You Also.
Iraqgunz
10-09-13, 01:15
The port size is whatever PSA tells them to put in it. Unless they do them in house. You should probably contact them.
aguila327
10-09-13, 05:38
Just curious, but what difference does the gas port size make as far as taking your FSB off?

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Iraqgunz
10-09-13, 05:43
He wants to know the port size. The only way to do so (without asking and assuming that he gets the right answer) is to remove the FSB and then a set of pin gages to check it.

Why he wants to do it hasn't been addressed. Either morbid curiosity or he is going to try and tune it (I assume).


Just curious, but what difference does the gas port size make as far as taking your FSB off?

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aguila327
10-09-13, 07:00
Not much of a tinkerer, I just shoot em and fix em.

Although I will admit that I am always fascinated by the projects and fixes people inquire about and start here.

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RWH24
10-09-13, 14:58
IG, You are correct. This a new upper to me so trying to decide which buffer weight to start out with.
Think I shall start heavy and work my way back lighter if any functional problems arise in the beginning.
The upper is slightly used, probably just past break in, 3-500 round count.
:thank_you2:
RWH24
10-09-13, 15:02
Why he wants to do it hasn't been addressed. Either morbid curiosity or he is going to try and tune it (I assume).
In the beginning I had no clue about all the variables to make the AR run correctly, that is until I came to M4carbine. I probably over research things, but this is another piece of my firearms learning curve.
Chumly
10-09-13, 16:02
I emailed them with the same question.



"

The gas port size on the majority of our mid length barrels is .078”. I hope this helps. Please let us know if you have any additional questions or concerns.



Thanks,



Dee W.

Compliance Department

Palmetto State Armory

Phone: 803-724-6932

Fax: 803-788-7979

compliance@palmettostatearmory.com

"
RWH24
10-09-13, 16:07
Thank You Chumly,
You got a faster response than I usually do. Not knocking PSA CS/Tech line.

PSA seems to ship Carbine wt buffers in their builds. I will start with an H2, go from there.

Again Thanks.
Chumly
10-09-13, 16:14
No problem. Not so sure I got a faster response though, that email was from a few weeks ago.
_Stormin_
10-09-13, 16:28
If you're running the standard spring an H2 should run just fine. I helped a friend set up a similar rifle (same PSA upper), and with a standard carbine spring and an H2 he had zero issues, even with some of the lower powered commercial .223 ammo.
Iraqgunz
10-09-13, 16:32
I'm pretty sure we ran a middy at one point with same port size and a blue Springco spring with H2 buffer and it was good to go.
Chumly
10-09-13, 16:36
I just noticed you have a light weight barrel. My question was a general inquiry. PSA said ".078 on MOST". Not sure if they are referring to the mostly .750 barrels. It may be different on your .625 (barrel diameter at the gas port could certainly change the equation).

It really doesnt matter, you may still need to tinker. However, it sounds like some people above gave you a starting point regardless.
RWH24
10-09-13, 22:14
Chumly,

Under the handguards tapers from .640 to .600, then the gas block is .751. In front of the FSB it measures .612 to .695 at the MD.

:D
Chumly
10-09-13, 22:33
Sorry. I assumed it was .625 being a light weight barrel. See, there is a lesson right there. Don't assume anything. lol

Also, I am far from an expert. I was just saying that changing the barrel diameter at the gas port would change the overall volume/dimensions of the gas port itself and effect pressure etc. Some of our much more senior and experienced members would be able to tell us both if the changes would matter enough to warrant different port diameters.
Iraqgunz
10-10-13, 01:28
To the best of my knowledge the port size is exactly the same whether it is LW or standard.


I just noticed you have a light weight barrel. My question was a general inquiry. PSA said ".078 on MOST". Not sure if they are referring to the mostly .750 barrels. It may be different on your .625 (barrel diameter at the gas port could certainly change the equation).

It really doesnt matter, you may still need to tinker. However, it sounds like some people above gave you a starting point regardless.
GunnutAF
10-10-13, 12:51
RWH24
If your pic is correct you have a PSA barrel mounted to a BCM reciever -not a PSA upper assembly. So it looks to be someones build so who knows what they did when they built it!:rolleyes:
JC0352
10-10-13, 15:31
RWH24
If your pic is correct you have a PSA barrel mounted to a BCM reciever -not a PSA upper assembly. So it looks to be someones build so who knows what they did when they built it!:rolleyes:

That BCM logo is on the bcg, not the upper.
RWH24
10-10-13, 23:06
That BCM logo is on the bcg, not the upper.
BCM BCG.

PSA built upper w/o BCG and charging handle

http://pic20.picturetrail.com/VOL1321/4777050/24318160/407761132.jpg