how hard is it to drill a barrel for a fsp? what barrel contour do I need to do this?

[Sidneyious]

So I have been looking and emailing almost every single barrel maker and no one can do what I want.
Im making a smaller dissy, I need a 13.7 barrel with a carbine gas system that has a fsp out at the 11" mark so I can use this 11" handguard I have sitting around.

Im trying to use up parts and no one can seem to accommodate this task

[markm]

Manufacturer's use a special reaming machine to do this right. Have you tried ADCO??

The barrel would have to have the standard .625" O.D. or the larger .070? I think? I've seen BCM sell the FSB, but I don't know who buys them since it's exceedingly difficult to do correctly.

[vicious_cb]

So I have been looking and emailing almost every single barrel maker and no one can do what I want.
Im making a smaller dissy, I need a 13.7 barrel with a carbine gas system that has a fsp out at the 11" mark so I can use this 11" handguard I have sitting around.

Im trying to use up parts and no one can seem to accommodate this task

Unless you have a drill press and the proper jigs its better to just send it out.

[grizzman]

I wouldn't expect a barrel maker to perform this work. I would expect ADCO, or Retro Arms to be able to do the work for a reasonable price.

[MegademiC]

So I have been looking and emailing almost every single barrel maker and no one can do what I want.
Im making a smaller dissy, I need a 13.7 barrel with a carbine gas system that has a fsp out at the 11" mark so I can use this 11" handguard I have sitting around.

Im trying to use up parts and no one can seem to accommodate this task

Better off getting a fsb barrel and cutting it down

[titsonritz]

Bottom line...don't try in your garage.

[Leonidas24]

Better off getting a fsb barrel and cutting it down

OP wants the FSB at a non-standard location and isn't going to find a barrel to chop down with an FSB halfway between rifle and midlength.

The barrel would need to be a constant .750 or .625 past the gas block journal to pin an FSB. Some shops won't do pin jobs on melonite barrels, so take that into consideration. I know Rosco does a 13.9" carbine barrel that's .750 past the gas block, and FN makes 14.5/16" chrome lined barrels in the same configuration, but would need to be chopped to the desired length. D Wilson Mfg handled my last FSB pin on a Centurion Arms barrel and did a great job. Trajectory Arms would be another good place to check out.

https://www.primaryarms.com/fn-america-5.56-button-cut-carbine-government-barrel-16

[Todd.K]

You want a government profile barrel, without the M4 step down section. The front will probably need to be turned down to take a .625” FSB, unless it’s very close to .750” all the way to the front.
This one looks like it might take a .750” FSB, but would need to be cut and threaded to 13.7”.
https://www.primaryarms.com/fn-america-5.56-button-cut-carbine-government-barrel-16

Handguards are never exactly 7”, or 12” or 11”, you won’t be able to just get the barrel done separately.

The drilling and reaming could easily be done on small drill press. The fixture to hold everything straight would be hard to make in your garage.

[Sidneyious]

Manufacturer's use a special reaming machine to do this right. Have you tried ADCO??

The barrel would have to have the standard .625" O.D. or the larger .070? I think? I've seen BCM sell the FSB, but I don't know who buys them since it's exceedingly difficult to do correctly.

adco never came up in searches, I can get a cmmg base from brownells, its a 750 base

[grizzman]

ADCO is found on the first page of a Google search for "barrel FSB pinning service". Two other results were War Machine (pretty sure i've heard of them) and Rainier Arms (very well known and trusted).

ADCO re-profiled and re-parked a large frame AR barrel from chamber to gas block for me quite a few years ago, and it turned out great. If they can take material off of a barrel under the handguard, then they can take material off of a barrel in front of the handguard to make it .750".

[Sidneyious]

ADCO is found on the first page of a Google search for "barrel FSB pinning service". Two other results were War Machine (pretty sure i've heard of them) and Rainier Arms (very well known and trusted).

ADCO re-profiled and re-parked a large frame AR barrel from chamber to gas block for me quite a few years ago, and it turned out great. If they can take material off of a barrel under the handguard, then they can take material off of a barrel in front of the handguard to make it .750".

that wasnt the search keywords I used which I cant remember and I dont let google remember what I search for.

I think militia works might be able to get me a upper or barrel I need without having to get 5 companies to get me 1 item.

[Send it...]

AR15Barrels.com can do it.

[Sidneyious]

AR15Barrels.com can do it.

I will ask them, thanks, MW cant do it because apparently they get theirs from ballistic advantage and would charge almost 3 times the price for one.

[lazar]

AR15Barrels.com can do it.

He did a barrel re-profile for me last month, great work!

[everready73]

Buy everything you need and have John Thomas at Retro Arms Works do it. He is one of the best around and will have it done quickly IME

https://retroarmsworks.com/

[hoopharted]

get a centering bit to start your hole so your drill bit will not walk , you need a drill press , F marked front sight tower if the upper is a flat top , #31 drill bit ,cutting oil and a taper ream for the pins

mount the drill press solid , build a platform flush with the drill press table , take a block of wood drill a hole through it the size of your barrel then cut in half splitting the hole for cradle

if you look at the underside of the tower sight base without the swivel attached there is a hole they drilled to drill the gas port , what i did was tapped that hole and got a set screw from Lowes , with the dimple jig i dimpled the barrel for the setscrew , this ensured the port alignment and the set screw keeps the FSB true through the process

with the upper attached still you need to start aligning the orientation , place the barrel in the blocks you made and support the receiver end so it sits naturally ,clamp it down , take your centering bit and start a hole for on pin through the FSB , the centering bit will only allow you to do a started hole , place a drill bit in the hole so it sticks straight up and start aligning the bit with your drill press bit until the are parallel with on another from all angles, adjust support of receiver as needed to keep the orientation , the receiver will prevent the barrel from rolling and reclamp barrel in place with the bit aligned with the starter hole , you can use a square to double check bit orientation for a butt hole pucker piece of mind

just drill the hole slowly using cutting oil , let the bit do the work only applying enough pressure to allow the bit to cut , do not over heat the bit i would pull out and oil and clear debris , its not a race ,do not cheap out on bits and buy a couple , once the first hole is drilled , i used a nail gun and nailed the bracing i had for the receiver end together so i did not have to redo it all over again , take your taper reamer in a Die handle and start cutting testing it frequently with a taper roll pin , BEFORE it wants to drop all the way in stop reaming and use a roll punch to drive it in the last little bit , error on the side of caution , if it turns out you didnt ream enough then simply back the pin out and cut a very small amount more and repeat until you get it , you want it tight , but you dont want it so tight you deform the pin getting it in , i can see where it would be very easy to go too far , then you would need to find larger pins if they even have them ,so go slow , no rush , take your time , once that pin is in repeat for the second pin , then blue lock tight the set screw or you can do away with it and install the swivel

[NYH1]

I've never done one on a dissy setup. Done them on carbine and rifle setups, in both .625" and .750". All the one's I've done were on barrels that had the dimple on the bottom of the barrel for a gas block. I drill and tap the hole in the bottom of the FSP. Use a set screw to hold it in place on the barrel. Then I slowly drill the holes for the tapper pins from right to left in a drill press. Use a tapper pin reamer on the holes.

I've never had ADCO do any work for me. That said, I've only heard good things about them.

Good luck, NYH1.

[Sidneyious]

One step closer and now to figure out the hard stuff.
https://i.ibb.co/TtjNfT3/14-5-1.jpg (https://ibb.co/rH8Xjtr)
Mas Defense upper(cerro forge)
BA barrel, 14.5 middy
Stripped CMMG FSB(im a dolt)

I need a charging handle and a yhm sRx flash hider for a p/w.
I need to figure out optics choice, I am wanting to put my p4xi in a taller mount for my 12.5 but an ADM 1301 mount is too low for a FSB gun.
Still need to figure out optic choice

[grizzman]

The purpose of mock dissipators is to give a long sight radius for use with irons, so optics are irrelevant.

The correct question is, "What rear sight should I use?", and the answer is an A2 detachable carry handle. Another really good answer would be to an LMT cut down rear sight assembly.

[titsonritz]

The purpose of mock dissipators is to give a long sight radius for use with irons, so optics are irrelevant.

The correct question is, "What rear sight should I use?", and the answer is an A2 detachable carry handle. Another really good answer would be to an LMT cut down rear sight assembly.

I assume you mean their L8A (https://lmtdefense.com/product/tactical-rear-sight/)?

[grizzman]

Yes, I was referring to the L8A. I suppose "cut down" wasn't a very good choice of words.

It works as well as my old Colt factory carry handles, without the extra material that doesn't serve a purpose for me....except looking appropriate.

It's actually in stock directly from LMT right now. They're definitely not the easiest sight to find in stock.

[Sidneyious]

eh im not really down on the detachable carry handle look, when its formed into a single unit yes its nice.
Im probably going to find some fixed magnification optic I like.

Not quite sure yet, I definitely dont like lpvo on a standard height mount with a FSB. The blur thats supposed to go away is still there.

[grizzman]

Deleted.....

[Sidneyious]

Decided what to do just need to figure out the execution of said idea.

What you see here is a m4 gov profile 14.5 barrel and a .750 fsb stuck together with griffin armament m2 shim kit shims.

Need to contact griffin to find out what size these shims are.
So I can make some sort of spacer.

Everything is temporary right now.
https://i.ibb.co/KrTNTnt/14-5-3.jpg (https://ibb.co/XCcycHn)
https://i.ibb.co/JrHwPD8/14-5-4.jpg (https://ibb.co/zPZTwqC)

[498cm3]

If you need barrel shims that stand in for handguard cap, get one from Fulton.

[Sidneyious]

I just cant even

https://i.ibb.co/zJ9Xzxt/Screenshot-2023-04-14-at-7-21-31-PM.png (https://ibb.co/Ryr3qbJ)
https://i.ibb.co/6BhTV8K/Screenshot-2023-04-14-at-7-21-26-PM.png (https://ibb.co/SrTMWck)