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Old 12-01-2011, 09:05   #5
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Join Date: Feb 2010
Location: North Carolina
Posts: 3,325
Originally Posted by RustyDaleShackleford View Post
Specifically what parts are different in a piston vs DI build? I can't seem to find parts descriptions.

I've heard that you actually want your castle nut not staked, while you do want your gas key staked. They say it's because the castle nut is unlikely to come loose, is difficult to remove if you decide to, and you can ruin many tools doing it.

I'm not worried about having trouble building the upper from scratch, and would prefer it if it's at all cheaper. I've got a cousin who lives nearby who's built several AR-15's and who said he'll help me and let me use his tools. So the cost of tools isn't a problem.

Is my thinking right? 1:7 is the fastest barrel twist rate, and since it stabilizes the heaviest bullets, that covers me for any bullet weight I'd want to use. Right?
With DI you have a gas block and gas tube. The piston system replaces these with the piston system. The BCG can also be modified depending on the system. One of the big downsides is replacement parts, all the different systems use different parts. You can get DI stuff anywhere. It also adds weight to the end of the barrel throwing off the balance unless you use a heavy stock.

Yes, staking the castle but makes it hard to remove, that's the point. If it backs off your day is over. For a range gun it's not a big deal but it is for a fighting rifle.

Yes, get a 1:7 barrel. Unless your going to be shooting 40gr bullets you'll be fine.

Did your friend build his upper? It's not just the tools but the know how. If your up for the challenge and troubleshooting go for it. In the end your still not going to save much money, if any. With PSA and Spikes selling for $400-$500 complete it's hard to beat.

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Last edited by boomhower; 12-01-2011 at 09:07..
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