First upper build questions

[Uncle Krunkle]

I've been researching doing an upper build. I already have a BCM barrel and an upper. I'm going to put a free float handguard on, just haven't decided on one. I noticed that most low profile gas blocks use just set screws. Should I mail it to RainierArms or find a gunsmith that will also pin the gas block? I'd like for all my AR's to be rugged and durable. But is pinning the gas block overkill or just playing it safe? I've read that there's a jig that makes pinning a vltor block easy. BCM dimples their barrels so the set screws have something extra to bite into, do those dimples only line up with a BCM gas block or does the vltor line up as well?

 

[jrumann59]

Pinning it is the most preferred, it is done and that is it. But I have the jig and it looks simple and pretty foolproof. I will be dimpling mine because I can see me changing things adn it would get quite expensive if I had to drop it off at the smith everytime I changed barrels or profiles. Dimpling is the next best method to pinning. They make jug for dimpling for set screw blocks and a jig for pinning.

 

[04RWon]

Pinning it is the most preferred, it is done and that is it. But I have the jig and it looks simple and pretty foolproof. I will be dimpling mine because I can see me changing things adn it would get quite expensive if I had to drop it off at the smith everytime I changed barrels or profiles. Dimpling is the next best method to pinning. They make jug for dimpling for set screw blocks and a jig for pinning.

Would this be an option for someone with a yhm flip up fsb thats a screw on? I dont believe my barrel is even set for a pinned fsb.

 

[Russ D]

Pin that Fu&$er.

 

[jrumann59]

Would this be an option for someone with a yhm flip up fsb thats a screw on? I dont believe my barrel is even set for a pinned fsb.

I do not believe the jig in question can do FSP. Even the Jig for set screws will not work on the FSP

For the money they seem well worth it.

Here is the dimpler:

http://www.rainierarms.com/?page=shop/detail&product_id=1089

Here is the pinning jig:

http://www.rainierarms.com/?page=shop/detail&product_id=1398

 

[clandestine]

Would this be an option for someone with a yhm flip up fsb thats a screw on? I dont believe my barrel is even set for a pinned fsb.

YHM FSB Bases are Clamp On and are about the worst setup made reliability wise. The barrel has nothing to do with pin options, the gas block does.

 

[clandestine]

Pinning it is the most preferred, it is done and that is it. But I have the jig and it looks simple and pretty foolproof. I will be dimpling mine because I can see me changing things adn it would get quite expensive if I had to drop it off at the smith everytime I changed barrels or profiles. Dimpling is the next best method to pinning. They make jug for dimpling for set screw blocks and a jig for pinning.

Pinned setups are easier to remove than dimpled set screw applications.

WHen you loctite the set screws into the dimpled recessed you have to heat up the Gad Block to remove. A Pinned GB only requires the pin to be driven out either way.

 

[04RWon]

Yeah, if i kept this upper id want to get a pinned fsb. Doesnt the barrel have to habe cuts in it for the pins to go through? I dont know if mine does. I didnt look when i put the yhm on it. Originally it was a clamp on gas block.

 

[clandestine]

Yeah, if i kept this upper id want to get a pinned fsb. Doesnt the barrel have to habe cuts in it for the pins to go through? I dont know if mine does. I didnt look when i put the yhm on it. Originally it was a clamp on gas block.

Thats what pinning does. It drills through the Gas Block and the Barrel creating a "pin channel'. Its similar to what a factory FSB has, but they use taper pins.

You can also taper pin a Low Profile Gas Block but it isnt necessary.

Pinning is the best method because it cant shift from hits, or losen under vibrationa and heat like Set Screws and Clamp On versions do.

The Gas Block area is one of the most critical parts on the AR. Having the proper Gas Port size and having a STEEL FSB/Gas Block thats pinned. ALuminum FSB's will gas erode and allow blowby which can result in short stroking/malfunctions.

 

[04RWon]

So i need to get a fsb, pins, and have it done

 

[clandestine]

So i need to get a fsb, pins, and have it done

The smith should provide the pins. just need the fsb.

 

[armed ferret]

http://www.ar15.com/forums/t_3_4/22...__GAS_BLOCK___Step_by_step_instructions_.html