After I get a few more milsurp weapons, I plan on building at least one AR. First will be a 20" varminter. If I go for a second, it'll be a short carbine along the m4gery lines. Now, on to my question. Supposing I used the same lower for both and just swapped uppers depending on intended usage, would a multi-position stock have any adverse effects on accuracy when using the varmint upper?