View Full Version : H&K MR556a1 Upper Buffer and Spring

02-15-2012, 8:39 PM
I have a Spikes tactical lower paired with a MR556a1 upper and was wondering if I actually need to have the HK buffer and the buffer spring. Would I cause damage to my upper if I just use a standard AR 15 spring and buffer?

02-15-2012, 9:48 PM
Yes you do, and yes, damage would occur if you didn't. The HK action spring (it's an action spring, not a buffer spring, you're not married to your sister, act like it) is much stiffer and the buffer is heavier then a DI action spring and buffer. This is because the piston system is a direct mechanical system and does not have the gas cushion and delay that DI systems have. Your gun will cycle way too fast and tear itself to pieces using a standard spring/buffer.

That said, there ARE heavier springs and buffers that work with the HK upper that are not manufactured by HK (Wolf extra power CAR spring comes to mind, not sure on the buffer) if you somehow came by an upper without the buffer and spring (and tube).