6.5 Grendel buffer

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I am building a 6.5 Grendel with a radical firearms 20" upper on a spikes forged lower. I will put a magpul prs stock on a dpms tube since dpms is the only tube I can find for the prs. What buffer and spring combo can y'all recommend for proper function. I hear H2 is too heavy. Any help is much appreciated. If anyone knows of a better tube I would prefer not to use dpms if possible.