Outcrossing is crossing out to different varieties.
Unlike horses or dogs or even chickens, domestic turkeys are not "breeds". They are, for the most part, color varieties and by selecting the correct colors you can recreate most of the other color patterns. You can spend a lifetime learning genetics...
But, simply, if I had a Narragansett hen and crossed her to a Bronze tom, I would not have any Narragansett babies. If I had a Narragansett tom and crossed him to a Bronze hen, I would have some Narragansett females. By crossing the Narragansett females back to the Narragansett tom father, I would have both male and female Narragansetts. That is where line breeding is VERY helpful. But if the original tom was a poor specimen, those flaws would be magnified in his grandchildren and in future generations. Likewise if he was small, his offspring would tend to be smaller. Or if he was superb, his grandchildren could be even better.
