DIY low profile gas block , FN Mil sec Barrel and Aero Precision stripped upper

[zain]

Got a FN 20 inch barrel few days ago , market with 3S679 MP 5.56 NATO 1/7 . I wish to built an upper with free float rail system . For that set up , I essentially needed a low profile gas block and these things are insanely over priced in here. So thought to built a low profile gas block by performing a surgery on the barrel and to make a DIY low profile gas block. Here is the pictorial of the process


The barrel

Dis assembled the A2 sights / gas block

Grind and cut the A2 sights and sling swivel

The final product . A DIY low profile gas block

The operation was a success

Now , when it is done , I am bothered by a question

I intend to use an aero precision stripped upper . when I red its specification , it said that it has M4 feed ramps and I don’t know whether the aero precision stripped upper would be compatible with this barrel or not .
The learned and Seniors friends are requested to guide, kindly .

 

[Sherlock Gnomes]

Neat idea thanks for posting. Don't know about the feed ramps. Not experienced enough in the ar ways.

 

[Greenhorse six]

A little dremel work with a chain saw sharping bit works , go slow with the barrel in a vise and keep checking to the upper .

 

[zain]

the matter bothering me is as i do not live in US or Canada and i can not return any product once it reaches me . the stripped upper would cost me no less then USD 500.

The barrel is said to be M16A4 compliant , and i think M16A4 does not have M4 feed ramp

So i shall be grateful if some body guide me in clear terms that which upper should i ask for . The upper with feed ramps or without feed ramps

I think some of you friends , which have built an upper with a barrel of 20 inches , like mine , can guide easily

 

[hbean]

It would be helpful if you take a picture of chamber end of your barrel. if your barrel is ramped you will need a ramp upper

 

[Innercity]

The Aero uppers have m4 ramps.
not sure about your barrel but everything I've run across says the 20" has M4 ramps as well.

 

[zain]

The barrel on the right (wearing the barrel nut ) is my FN 20 inch barrel , while the barrel on the right is an M4 barrel , posed in juxta position for better and easy comparison

I think my FN barrel has standard feed ramps . I don’t know , whether or not , the Aero Precision upper I intend to use ,having M4 feed ramps , would be compatible with this barrel or not

I wished to have M4 feed ramps though

 

[BattleRife]

We will need a better photo than that.

it is not difficult to tell whether or not you have extended feed ramps. Look at the barrel extension from the side (bottom, actually). If the ramps create visible notches in the side of the extension, they are extended. If no notches are visible you have standard ramps.

 

[Innercity]

https://fnamericaestore.com/product/fn-15-upper-assemblies/

On the FN website.

FN’s proprietary Chrome Moly Venadium steel and cold hammer-forging process offer unmatched consistency and durability in every barrel produced. Each barrel and chamber is hard-chrome lined to MIL-STD 171, and barrel extensions have M4-style feed ramps regardless of barrel length. Barrels are individually high pressure tested and Magnetic Particle Inspected and each upper is test fired to ensure optimum function and performance before leaving the factory.


Also on the FN website.

For FN America eStore or online order related inquiries and comments, please email:
customerservice@fnamericaestore.com

or call:
(877) 308-7999
between the hours of 9:00 a.m. – 5:00 p.m. (PST), M – F
An Authorized FN America Distributor

 

[Leg]

That would be for their commercial offerings. If the barrel is USGI then it won't have m4 feed ramps.

I'd just get a non ramped upper for it, it will work with either barrel extension.

 

[zain]

We will need a better photo than that.

it is not difficult to tell whether or not you have extended feed ramps. Look at the barrel extension from the side (bottom, actually). If the ramps create visible notches in the side of the extension, they are extended. If no notches are visible you have standard ramps.

Here are the picture from the required angle.

I have got my barrel colored in Tan . The other barrel is an M4 barrel .

https://fnamericaestore.com/product/fn-15-upper-assemblies/

On the FN website.

FN’s proprietary Chrome Moly Venadium steel and cold hammer-forging process offer unmatched consistency and durability in every barrel produced. Each barrel and chamber is hard-chrome lined to MIL-STD 171, and barrel extensions have M4-style feed ramps regardless of barrel length. Barrels are individually high pressure tested and Magnetic Particle Inspected and each upper is test fired to ensure optimum function and performance before leaving the factory.


Also on the FN website.

For FN America eStore or online order related inquiries and comments, please email:
customerservice@fnamericaestore.com

or call:
(877) 308-7999
between the hours of 9:00 a.m. – 5:00 p.m. (PST), M – F
An Authorized FN America Distributor

I have sent an email to FN requesting them to clarify as to whether this type of barrel have M4 feed ramps or otherwise but the reply does not seem to be forthcoming any sooner.

 

[Leg]

Your barrel has standard feed ramps so you'll need a non M4 ramped upper unless you're going to modify the feed ramps.

 

[MrSharp]

I had to do that for my DD hand guard, tried the smallest gas block I could find at the time ( actually very small) but wouldn't fit, had to round the bottom a bit also to fit, but works great and retains the factory pins that I prefer to clamp on or set screw type.