15 round magazines, are Korean surplus mags ok?

[ewall]

By down loading to 27 rounds do your 30 round mags function properly with standard mag releases on older M1s? I have had an occaisional failure to feed with full 30 round mags but none after a few rounds are fired. I've been going to load up my 30 rounders to 25 and do a field test to see if the misfeeds stop.