Originally Posted by
DMF13
So your question caused me to recheck the add, and I just saw that upper has a Glock specific bolt, and not a "hybrid" bolt. My apologies for leading you astray with my suggestion above, and I will say this again in a separate post for the OP, to help ensure he sees it too. The bolt with that upper will only work with the Glock style lower, and again I apologize for missing that originally. I haven't seen a Glock specific bolt offered there before, only the "hybrid" bolts, and I completely overlooked that detail.
With regard to the rest, my understanding, and I'm no expert (not even close), is the stock Colt bolt is slightly heavier than the "hybrid" bolts that PSA and others have been using to make the bolt work with both "Colt style" mags, and "Glock" mags. So the theory, as I've been told, behind the heavier buffer, is to get a combined weight of the bolt and buffer up to the weight used in the Colt factory guns. I don't mess around with silencers, so I haven't looked into how any of that is affects buffer weight.
Supposedly the theory on the spring, is the flat wire spring holds the bolt closed with more force when the bolt is forward, but because of the mechanics of the flat wire spring, it has about the same force as a standard carbine spring when the bolt is to the rear. All of that, combined with limiting the travel of the bolt/buffer with a spacer or longer buffer, are supposed to soften the cycling.
Whether that theory is correct with regard to mechanics I don't know. The first of my friends/acquaintances to get a PSA AR9 got a "Colt style" gun with the "hybrid" bolt. A few of us really liked it, and bought various iterations of barrel lengths and "Glock style" lowers, all with the "hybrid" bolts. When we all commented on how much harsher the cycling was on our guns, the first guy explained the issue with buffer length/weight, and the use of the AR10 flat wire spring. We all tried it and liked it.
See my note above, again when I read your comment I went and looked again, and realized I missed that detail. I really am sorry for that. My understanding is that's due to the bolt used, but PSA customer service might be able to tell you if that's the case.
Yeah, that's got the "hybrid" bolt, and should work with a lower that takes "Colt style" mags.