Changing the "recipe" has screwed up lots of guns but you have to remember tomato soup has to start with a tomato. The standard is only one weight rifle buffer and spring. If one won't run on the standard buffer/spring, it's time to look for the problem.
JP and some of the others used lighter and heavier buffers, carriers, springs and such to reduce recoil and muzzle jump to increase speed of the follow up shots. A very specialized and finicky proposition.
I do know of one 70's made Colt SP1 carbine that will not run with an A2 stocked lower. Evidently the gas port was sized to run with the lightest carbine buffer but that's strictly on a 16" barrel and carbine gas system.
What's the load it won't run?
