In short, regardless of what the Army settles for, Hemvärnet will focus on 5.56 NATO, and there are a number of reasons for this.
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The cost might only be approximately 1 SEK (~90 cents) more for a 7.62 NATO round as Peru explained, but giving just three mags of thirty rounds to all 26,000 soldiers will already cost you well over two million Euros more with 7.62 NATO compared to 5.56 NATO – and then we get back to the fact that the rounds are heavier and the magazines longer.
It doesn’t stop there. Such seemingly simple things as how many firing units you can fit in a given exercise area simultaneously also comes into play. When looking at the larger area needed by a unit shooting 7.62 mm compared to one equipped with 5.56 NATO, this directly translates into how efficient the parent unit can be with the precious training time allocated to it, a rather unsexy question but one that have consequences in the real world where budgets and training days are limited.