hi, i have been looking at src m4`s and mamba from just bb guns. are they any good and where would be the best place to get mags. m4 https://www.justbbguns.co.uk/product/2-tone-airsoft-guns/2-tone-aeg-rifles/4096/src-m4-ris-gen3-airsoft-gun mamba l https://www.justbbguns.co.uk/product/2-tone-airsoft-guns/2-tone-aeg-rifles/4322/sr4-mamba-l-gen2-blue