Thread Differences in Investarms Locks

[Twosteels]

Alright, a question for the experts, Why are the Lock Bolt threads different for Flintlock, Percussion, locks for T/C and Lyman guns with in the same brand, I.E. example Lyman. (pictured). Was this just for marketing? The locks pictured do not have the same threads, The flinter is threaded 4-.70 mm. I always thought the percussion was threaded 8-32 but one of those will only thread in about 3/4 turn. The thread checker I have only has holes. The threads in the percussion lock could be 5-.80mm or 8-36. Anybody?

 

[Phil Coffins]

TC will be English and Investment will be metric. Each manufacturer will decide what to use and we must figure it out.

 

[LonestarShootR]

Some imperial threaded fasteners are close to metric fasteners.
Using metric and imperial thread pitch gauges work well for distinguishing the difference.
Just an FYI, imperial counts the threads per inch while metric are the distance between the threads.
phil is correct what he says about manufacturers.