first off, there is a difference in the cobray m-11s......some were made by SWD and some by "others" and assembled as completed guns.For example, the original m-11 bolt made by SWD, didnt have a snake logo on it, seen some with the logo stamp,they were made elsewhere also the early ones did have a non free spinning tall cocking knob that could be turned via a machined ball detent slot in the bolt...not like the free spinning small style used on them today..the internals are also different on an original vs "other" makes but will fit and work in the same gun,many people assembled them with the non-original parts and sold them as a m-11.the trigger slap is horrendous and matching surfaces on the sear-bar are out of alignment. The magazine the cobray m11 uses vary,normally, zytel mags but they can be adapted to use a large variety of mags from different guns such as the sten mags,madsen mags ect..the zytels wear out eventually at the feedlips but now there is a steel insert that has fixed that.
the masterpiece arms version is well made,some small modifications to the bolt on the original design to eliminate the "clone" version problems(trigger slap) and pretty good machinework and heat treating.they use sten mags only,which are two thirds cheaper to buy than the zytels the cobray uses.
no experience with the other makes.it depends on how much work and thought goes into it I guess but the internals on all the clones will interchange.
An original might be pricy to find but are also neat from a collectors standpoint, the MPA version is cheaper but very well made.
