FWIW I have both matchlocks mentioned:
1) 75-cal fishtail, trigger operated, later English civil war type match lock by Middlesex Village Trading
2) 62-cal fishtail, trigger operated, caliver matchlock by Leonard Day
I proofed the 75 by shooting 2 balls over 80-grns 2Fg. It may not be a 'proof' load, but that's what I did, since I use single ball loads and 40-80 grain charges.
Since Mr. Day makes all of his locks from casts of originals, surely it's a more historic representation. And while the MVT one may be clunky ...heck, but my views of originals they ALL were clunky! I honestly can't say it's more clunky than it should be, as I have never hefted an original.
But I will tell you that the 75-cal from MVT has been 100% reliable and I've never had a misfire! I also have zero negatives about the build quality - none.
And honestly? For some reason that I cannot explain - and it isn't the caliber - but I enjoy shooting it MORE than I do the one Mr. Day made ... go figure.
FYI, I have since switched to 1Fg powdah for my larger caliber or long barreled (up to 60" long) muzzleloaders and I love it! Softer shooting and better accuracy.