im building up a mauser and i plan to convert the bottom metal to use m14 magazines. i want to find some really cheap magazines that are decent quality (need to be able to actually hold 10 rounds) perferably able to run 2.85 OAL. ive heard that some magazines cant is that true? i would like mags under $25. are 9.14 or national magazine good enough? they dont need to run well in an m14 they just have to not break.