In search of the custom AR-10 build and stay within a budget, people look online for deals. They read articles, watch youtube videos, get confused and buy something that they are promised will work with their AR10, only it is not.
It's a common question that I always get - I bought this carbine AR-10 set from a reputable manufacturer (no names will be published out of respect), but I have a double feeding or not enough pressure to activate the bolt. Upon sending me the pictures of their stock "guts," sure enough, I find AR-15 carbine spring with AR-10 buffer, or AR-15 buffer and AR-10 spring, or just simply, AR-15 buffer and buffer spring. Yes, you guessed it, that will not work with your AR-10 .308 upper.
So how do we know what we bought (aside from being advertised as such). Here are few simple rules of thumb:
Gas tube - yes, I will probably get attacked by some, but it is totally interchangeable between AR-15 and AR-10 rifles.
Carbine AR-10 buffer. Totally different! Generally, 2.5" long and a bit fatter than you regular AR-15 buffer. So, if you bought an AR-10 advertised set and got something that resembles AR-15 - that won't work in your AR-10 rifle. Period.
Carbine AR-10 buffer spring. Very different from AR-15. Usually, it is about 25-27 coils, maximum. Much stiffer than your standard AR-15 buffer and coils spread further apart. So, please check when you get your order that you got the right parts. If they appear a lot like AR-15 "guts," probably that's what you got!
Your true carbine AR-10 .308 buffer tube set is available at Moriarti Arms. Happy building!