I acquired a 20" pre-ban FN A2 barrel which naturally has a bayonet lug and threaded end for a flash hider a few years ago.  I plan to do my first AR build around it soon.  It doesn't have a gas tube so that's one of the parts I'll need to order with my kit.  The pin which holds the front end of the gas tube is missing from the FSB.   Is this a roll pin, and where can I get a replacement?  

I don't have a flash hider either.  I'd like to get one that looks exactly or close to the USGI hiders.  Where can I find one of those?

Also, a more basis question:  Are the gas block and the FSB the same thing?  Or is the gas block an internal part of the FSB?

C'mon, somebody must know the answers!

Yes, the gas block is built into the FSB on a standard AR.

Look here for the parts you need: www.adcofirearms.com/barrel_parts.cfm?page=woa

Quoted: I acquired a 20" pre-ban FN A2 barrel which naturally has a bayonet lug and threaded end for a flash hider a few years ago.  I plan to do my first AR build around it soon.  It doesn't have a gas tube so that's one of the parts I'll need to order with my kit.  The pin which holds the front end of the gas tube is missing from the FSB.   Is this a roll pin, and where can I get a replacement?   I don't have a flash hider either.  I'd like to get one that looks exactly or close to the USGI hiders.  Where can I find one of those? Also, a more basis question:  Are the gas block and the FSB the same thing?  Or is the gas block an internal part of the FSB?

you can find roll pins/gas tubes from: ADCO, Eaglefirearms.net, Del-Ton, DSGArms, etc from the EE/Industry board--should be less than $10 for both

you will need an A2 FH--same places above should have em

usually....the std. FSB includes the gas block area and a front sight placement area; h/w, not all gas blocks have a place to mount a front sight (i.e. low profile gas blocks)

Thanks guys.

That exploded view shown in the link to ADCO/WhiteOaks barrel parts web page answered my questions about the gas tube roll pin & flash hider.  I plan on getting my stripped lower and lower parts kit from ADCO anyway, so I'll add the gas tube, flach hider, crush ring and TWO roll pins (in case I mess up the first one) to the order.  And from what you said, my standard A2 FSB has the gas block inside it.  

Front sight base typically refers to a complete front sight.  Gas block typically refers to something that goes in the same place, directs gas the same way, but doesn't have the sight tower on it.  Gas blocks freqently attach by clamping on or using set screws, where fsb's are pinned through the barrel.
To put it simply, a gas block is a fsb without the sight tower.

Quoted: Thanks guys. That exploded view shown in the link to ADCO/WhiteOaks barrel parts web page answered my questions about the gas tube roll pin & flash hider.  I plan on getting my stripped lower and lower parts kit from ADCO anyway, so I'll add the gas tube, flach hider, crush ring and TWO roll pins (in case I mess up the first one) to the order.  And from what you said, my standard A2 FSB has the gas block inside it.

I see, said the blind man.  That DOES simplify things.  Somehow I'd gotten the idea that the gas block was a little device inside the FSB.

Thanks, Jim.

Quoted: I see, said the blind man.  That DOES simplify things.  Somehow I'd gotten the idea that the gas block was a little device inside the FSB. Thanks, Jim.

sorry for the rough description