My MK18 runs fine (Flawless:D) with the H buffer and standard buffer spring it came with, shooting both steel and brass ammo. I’m thinking of replacing the H buffer with an H2 and Red Sprinco spring but think I may develop cycling issues shooting underpowered steel ammo. Any good or bad opinions on running this combo?
If it’s running flawlessly, why change anything at all?
I’m not sure what the red springco spring is supposed to do, but I do know that using an H2 on my Centurion Arms MK18 made it not lock back on an empty mag, and also had issues where it would eject a spent casing but was unable to chamber the next round in the magazine. I switched to an H buffer and it’s been working fine since then.
The red spring is a extra power buffer spring designed for 16 inch carbine length guns, which I have in my 6920s for enhanced reliability and blue springs for my middies. I was curious to see if anyone ran that combo before and if any issues evolved. I may swap springs this weekend just to gain first hand knowledge in what actually happens with the setup. If issues develope, I’ll just swap them back. It’s more of an exercise in curiosity and having too much time on my hands.
I’d up the buffer to H2… but forget the spring ponzi scheme.
Well…I wouldn’t quite call it that, but I respect your advice. I know several of you guys have played with buffer weights and springs so I wanted to know your collective opinions on optimum reliability with this setup. The Red springs have worked out quite well with my two 6920s, as well as the Blue springs for my middies, all with H buffers. The Blue also works well with the 12.5 NSR upper with the H2. I’m going to try the blue and the red in the 10.3 upper this weekend, as well as the H2 and standard spring. Since I’m going to replace parts, rings and springs on 3 bolts this weekend, I figured I’d knock out the buffer/spring testing as well to get it out of my system while doing a function test with the rebuilt bolts. In addition, all the Sprinco springs also came with enhanced 5 coil extractor springs so I considered that an added bonus.
You’re banned! 
I was looking into Sprinco springs a few weeks ago, and was curious (perhaps somebody could explain) why the stiffer springs were recommended for longer barrels, and the “softer” ones for SBR’s. I thought that it was SBR’s, with their shorter gas systems, that needed stiffer springs (and heavier buffers) to slow down the carrier speed, in order to reduce the stress on parts due to the higher gas pressure from a shorter gas system length.
Since heavier buffers are recommended for SBR’s to slow down the cycle, wouldn’t it make sense for a stiffer spring to do the same?
As I understand it, yes, barrel length dependent, but you can only go so far before enter a point of diminishing returns, if going far beyond the systems setup or manufacturer’s recommendation. A proper balance must me struck. It’s the reason why Springco recommends color/buffer combinations depending on barrel length and gas system used. It’s like when I was a kid, a neighbor was home on leave and drove heavy trucks on active duty. He thought pouring heavy truck lube into his mustang would increase performance, but in the end, resulted in a seized up engine. My intentions are of experimenting to see the effects of a stronger spring not designed for a 10.3" barrel. I do not have any intention of keeping it in that configuration.