LMT Defender 2000 AR Feeding Issue

[soundqplus]

Hello all. Thought I might run a problem by you experts and see what you think. Every once-in-a-while, I have a feed problem. Action seems to short stroke and fails to chamber a new cartridge. Previous cartridge ejects fine and bolt fully closes into battery. However; no cartridge in chamber. Click. Cycle action, chamber new round, gun runs great for awhile. Very intermittent. This has happened with different magazines as well. OK, weapon is an SBR (10.5" bbl) LMT Defender 2000 AR. All ammo is commercial, no hand loads. I am leaning torwards buffer/spring. Might I need to change to a lighter/softer buffer/spring being an SBR? A little confused which would have more pressure, 16" bbl or 10.5". Am I way off or does this seem like a likely cause for the misfeed? If so, do they offer lighter/softer buffers/springs? I removed my buffer/spring assembly to check and see if there were any identifying marks, but saw none. Didn't completely disassemble buffer, has drift pin and I didn't wanna get to ahead of myself Thoughts? Thanks...

 

[inherentical]

I'd try milspec-pressure ammo.

 

[bryanZ06]

I don't believe his ammo is the issue. He's using quality, commercial .223 ammo (I know him, I'm not just assuming what he's using). I've shot quite a bit of .223 through my Colt 6920 (mostly because 5.56 is basically impossible to find) and never had the same issue.

 

[Jeff White]

It sounds like bolt bounce. You need a heavier buffer, not a lighter one. What's happening is the bolt is cycling with so much speed that it's going forward too fast for the magazine spring to lift the next round high enough to be picked up.

I've seen this happen with full auto much more then with semi autos, but I'd bet a switch to a heavier buffer would fix the problem.

 

[ugaarguy]

The shorter bbl and shorter gas system will have higher pressure than a longer bbl and gas system. Higher pressure ammo wouldn't solve the problem. As Jeff White has already stated it sounds like buffer bounce. Heavy buffers run from weights of H1 to H3. They should be marked as such on the buffer face.

 

[soundqplus]

So I had it exactly backwards. Any recommendations for maker of heavier buffer? Found MGI RRB, but they want an arm and a piece of a leg for that one Thanks for the replies guys...