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-ameri...ment-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-ameri...ment-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".