Amorn, yes this will fit in your Del-Ton DT Sport. Have a great day!

Amorn, yes but test for function to make sure this Promag works reliably. Extra capacity with low reliability is a recipe for disaster. I would spend the extra $ and get the Magpul (Del-ton does not sell Promags) : del-ton.com/Magpul-PMAG-40rd-Gen-M3-Polymer-Magazine-p/mp1052.htm

Or if steel mags are your preference E-lander makes high quality steel 40rd magazines in stock here.
budsgunshop.com/product_info.php/products_id/713088551/e-lander+magazine+5.56x45

Promag are notorious for not being reliable, and failing often, Pmag on the other hand makes magazines for the US Marine Corp, and are pretty much the gold standard for AR15 magazines. 40rd Pmag (that will fit in your delton) in stock here
budsgunshop.com/product_info.php/products_id/1130/magpul+pmag+m3+223rem+40rd+black

Amorn, yes this will work fine in your delton 223/5.56. promag has iffy quality but I actually have this same magazine and it's worked just fine for 2 years so far. Here's a link to a magazine I'd recommend, it's only 30 rounds but I own alot of them and they function flawlessly every time. Hope this helps, link here if interested............ budsgunshop.com/product_info.php/products_id/1122/magpul+pmag+m2+moe+magazine+ar-15+.223+rem+5.56+nato+30rd