so i got my new del ton 2'' a4 upper today and went to test it out. first shot fired then pulled the trigger again and clickwell i pulled back the charging handle and it apparently failed to load the second round...well i let it go and chambered the round okay and i fired it...after the second shot i didnt even have to pull the trigger to know that it didnt feed because i felt it was weak like at the end of a mag. so now i know it is short stroking. after i realized the problem i swapped ammo from 55grn polymer wolf to adcom m855 55gr and the problem went away...does anyone know what could be wrong?is it as simple as my new upper doesnt like wolf? is this a strange situation or anyone else share this experience? if it helps this is what i was running on the rifle:
superior arms lower
rra lower parts kit buffer/bufferspring and a2 buttstock
del ton a4 20'' upper
bushmaster mag

Not strange at all. It is a new upper and might have needed to break in a bit. Fire another 100 rds. or so and then try the Wolf again. If the problem returns then you will know. Either way you will know. Also try different mags. You will not hear anything good about Wolf from me so I will say nothing.

i see... i have a couple colt mags im going to try out tomorrow. thanks for the tip