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Ride4frnt
11 June 2014, 20:42
For Christmas I bought my dad a scope and mount he wanted for his bushmaster HBAR. Upon mounting it he decided that he didn't like the A2 FSB in the scope picture. Easy enough fish, just have to get him a low pro gas block.

My questions are these. When I go to remove the FSB, am I going to need a new gas tube, or at the very least a new gas tube roll pin?

His rifle has a carbine length GI handguard (he's really not into spending money to modernize his weapons). When I go to change the gas system, is the delta ring etc. going to need to be cut off, or does the gas tube go through the ring without hassle? I've never taken one apart with a delta ring.

Final question is, are there any relatively inexpensive free float or drop in rail systems out there that will work with a standard barrel nut? He's not really into a lot of flash (4 feet of picatinny rail he will never use). I'm thinking tube style with picatinny on top, but again, relatively inexpensive?

Thanks for any help guys. Trying to do this for him for Father's Day.

UWone77
11 June 2014, 21:04
Well you could go 2 different routes with this.

First, just shave off the the FSB with a dremel. Nothing is going to be stronger than a pinned FSB for a gas block. Numerous videos on YouTube on how to do this.

Second, you could do what you originally wanted to do and replace the FSB with a lopro gas block. Some FSB are easier to get off than others. Like I mentioned in another thread, I'd use some Kroil to soak the pins with first, and then use the Brownells FSB block to pound out the pins. You should be able to reuse the gas tube since it doesn't sound like he's had the rifle that long, but I'd get a new gas tube roll pin.

Once you get the FSB off, you can use a standard armorers wrench and remove the barrel nut, which will make removing the delta ring easy.

Standard Barrel nut compatible handguards I'd consider... Fortis REV and the Rainier Arms Evolution.

camomike
11 June 2014, 21:18
Like UW stated, Personally I'd just cut the FSB. Leave it pinned in place. Same goes for the delta, it's easy enough to cut that with a dremel as well. Another 2 options would be a Troy alpha or the Midwest gen2 SS... Personally I like the looks of the locking mechanism on the RA Evolution and the REV rail more though.

TripleBravo
11 June 2014, 21:18
Removing the taper pins of a standard FSB is not usually as easy as it seems.

I also soak them in Kroil oil..sometimes for a day before even making an attempt to drive out those pins. I'd also invest in the block that's designed to help with this process. If you google it, you'll find a ton of videos showing how it's all done.

I'd use a new gas tube roll pin at the very least, and consider replacing the gas tube if he's got a bunch of rounds through it since you'll have it all apart anyway. Your talking about maybe $14 worth of parts there.

You can also use a dremel to cut off the delta ring if you don't want to remove the barrel nut and barrel.

For rails that work well with standard barrel nuts, the Fortis REV is a great option. For a more tubular design, take a look at the Troy Alpha rails.

camomike
11 June 2014, 21:23
One piece of advise... If you are going the cut FSB route; invest in a bottle of cold bluing agent. Re-blue the cut steel and oil it to avoid future rust on it.

GOST
12 June 2014, 05:07
I also recommend just shaving down the FSB, it's not that hard.

Ride4frnt
12 June 2014, 09:07
Okay, I'll see what he says about doing that. If not it's a 30 dollar fix for a block and tube

UWone77
15 June 2014, 09:15
Okay, I'll see what he says about doing that. If not it's a 30 dollar fix for a block and tube

Just tell dad the real way to fix this is with a completely new upper. He can sell the other upper to fund the new upper. [:D]

Judicator
15 June 2014, 09:44
^^^^ this is why I like this man haha.


Sent from my IPhone, please ignore spelling mistakes. Siri is dumb.

UWone77
15 June 2014, 10:07
For $499, I don't think you can do much better for an upper with a 12" Centurion Arms C4 Rail / Lopro Gas Block, and BCM Upper

http://www.bravocompanyusa.com/BCM-Standard-16-Mid-Length-Upper-Centurion-COSMO-p/bcm-urg-mid-16-c4-12-cos.htm

Another option... Rainier Arms, no handguard, but this does come with the better barrel, and MUR Upper.

https://www.rainierarms.com/?page=shop/detail&product_id=4518

Just use the exisiting BCG and CH for the uppers.

GOST
15 June 2014, 13:19
That price on that BCM Upper is going to tone hard to beat. That C4 rail is $320 by itself.