can standard/aftermarket FSB's be swapped between bbl's without issue? i was told something about tapping and drilling. why is this necessary and what does it mean. any help would be appreciated. thanks!

I'M NO EXPERT, but from what I understand:

the issue is with the grooves in the barrel where the tapper pins sit. the FSB is held onto the barrel with 2 tapper pins. You can remove the fsb by removing the pins (and gas tube). once you remove the fsb you will the grooves in the barrel. from i understand and have read here on the board, when you install a different  fsb, the holes may not line up exactly with the grooves in the barrel and if they do line up, the fsb may not be perfectly straight.

How can you avoid this? I don't know. I'd guess it would be best to buy a fsb from the same maker of the barrel? or maybe try the bolt-on type fsb's that have 4 cap screws that bolt the new fsb to the barrel, i think that would negate the whole pin issue all together.

like I said, I'M NO EXPERT, but that is how I understand it.  I'm sure others will be along to correct me.

good luck,

Gene

what are your plans for your old fsb?

Or you can eliminate the issue with clamp on.Check Yankee Hill Mfg,Armalite also has clamp on FSB.

Quoted: I'd guess it would be best to buy a FSB from the same maker of the barrel?

That wouldn't even work, as even the same manufacturer doesn't always drill in the same spots.

Quoted: can standard/aftermarket FSB's be swapped between bbl's without issue? i was told something about tapping and drilling. why is this necessary and what does it mean. any help would be appreciated. thanks!

As mentioned by everybody in the previous posts, the problem (if there will ever be one) will most likely be in the taper pin grooves / notches. Manufacturers sometimes space their grooves / notches differently from each other.

The dimension of the barrel is standard.

I am currently struggling with this myself.  

From what I understand at the factory the FSB and barrel are clamped down, and then the tapered hole holes are drilled in the two spots.  This makes the holes in the FSB and barrel line up perfectly.

I had a FSB with holes already dirlled, and used a dremel to bore out the nbotches.  The problem I am currently having is I got the taper pins separately, and they don't want to fit through the FSB properly, almost as though the other pinds tapred more.  A little dremel work ought to fix it.

I should also mention to I am shaving down the FSB to simpy us as a gas block- it is damn hard to notch the barrel and not get a canted FSB!

There is a reamer to size the holes.

Quoted: There is a reamer to size the holes.

I know, but try finding one in the suburbs of America.  Just one more things that you can't find, which can be added to the list of nylon strapping, house A/C fan belts, and more than one type of tool that wasn't made in China when at a 'hardware' store.

Anyhow, since I am shaving mine down (er, butchering it...) and it will be under some handgaurds I may just go the tap and setscrew method.  1911builder told me you can tap the FSB holes for 10-32 screws and dimple the barrel and it will work.  

Quoted: Quoted: There is a reamer to size the holes. I know, but try finding one in the suburbs of America.  Just one more things that you can't find, which can be added to the list of nylon strapping, house A/C fan belts, and more than one type of tool that wasn't made in China when at a 'hardware' store. Anyhow, since I am shaving mine down (er, butchering it...) and it will be under some handgaurds I may just go the tap and setscrew method.  1911builder told me you can tap the FSB holes for 10-32 screws and dimple the barrel and it will work.

If you need a reamer, contact me.  I can get you the part number that you can order online ASAP.  If you're real nice, I'll provide you with an easier source.



Additionally, the location of the taper pin holes is pretty much at the whim of the machinist at the time of mating the barrel to the FSB, so there is virtually no guarantee that any given FSB from one barrel will fit another barrel, even if the FSB/barrel assemblies are from the same batch.  A swap is 99.99% guaranteed to be a PITA for your average DIY/WECSOG builder.

Quoted: Quoted: Quoted: There is a reamer to size the holes. I know, but try finding one in the suburbs of America.  Just one more things that you can't find, which can be added to the list of nylon strapping, house A/C fan belts, and more than one type of tool that wasn't made in China when at a 'hardware' store. Anyhow, since I am shaving mine down (er, butchering it...) and it will be under some handgaurds I may just go the tap and setscrew method.  1911builder told me you can tap the FSB holes for 10-32 screws and dimple the barrel and it will work.   If you need a reamer, contact me.  I can get you the part number that you can order online ASAP.  If you're real nice, I'll provide you with an easier source. Additionally, the location of the taper pin holes is pretty much at the whim of the machinist at the time of mating the barrel to the FSB, so there is virtually no guarantee that any given FSB from one barrel will fit another barrel, even if the FSB/barrel assemblies are from the same batch.  A swap is 99.99% guaranteed to be a PITA for your average DIY/WECSOG builder.

Email sent.  Pretty please, with sugar on top?

2/0 taper reamer

www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1702334&PMT4NO=3563357

Taper pins

www1.mscdirect.com/CGI/NNSRIT?PMPXNO=2025771&PMT4NO=3563423

Would I be better off reaming the pin holes at this point or just using the 10-32 tap and set scres that I bought?  The whole sheband is covered by handguards and I already did a hack job shaving down the FSB, so ugly doesn't amtter, just functional...

Quoted: Would I be better off reaming the pin holes at this point or just using the 10-32 tap and set scres that I bought?  The whole sheband is covered by handguards and I already did a hack job shaving down the FSB, so ugly doesn't amtter, just functional...

It's way easier to drill and tap for set screws then monkeying around with taper pins especially since it's just acting as a gas block.

Quoted: Quoted: Would I be better off reaming the pin holes at this point or just using the 10-32 tap and set scres that I bought?  The whole sheband is covered by handguards and I already did a hack job shaving down the FSB, so ugly doesn't amtter, just functional... It's way easier to drill and tap for set screws then monkeying around with taper pins especially since it's just acting as a gas block.

Thanks for the advice, once I thought about the fact that I already have the tapping tooling and the set screws it seeemd kind of silly to even ask, but it is always nice to geta  second opinion before hacking away at something.

Either gotta go over to dad's to use the drill press this week, or just lay down the cash on a little benchtop one from Harbor Freight come payday...why is it every time I am working on an AR related project I end up buyig more tools??

Quoted: Quoted: Quoted: Would I be better off reaming the pin holes at this point or just using the 10-32 tap and set scres that I bought?  The whole sheband is covered by handguards and I already did a hack job shaving down the FSB, so ugly doesn't amtter, just functional... It's way easier to drill and tap for set screws then monkeying around with taper pins especially since it's just acting as a gas block. Thanks for the advice, once I thought about the fact that I already have the tapping tooling and the set screws it seeemd kind of silly to even ask, but it is always nice to geta  second opinion before hacking away at something. Either gotta go over to dad's to use the drill press this week, or just lay down the cash on a little benchtop one from Harbor Freight come payday...why is it every time I am working on an AR related project I end up buyig more tools??

That's how I got all my tools. I have a harbor freight mini mill that I'm going to try and use to do some taper pin work soon. We'll see how that goes.

LOL, I might go and buy one of their $40 drill presses this weekend just to finish up this set screw nonsense.