M9 Rifle Grenade questions

[BMG50]

A good friend of mine was having a clear out and gave me a couple of M9 rifle grenade bits. Wondering and figuring out is what in the world of American rifle grenades, can anyone help out, the first picture is a body the bottom half of the head but has a square shape to the lip where the top half would join together, unfortunately the screw thread is off centre but not a issue, is this from a practice rifle grenade as it looks like the square bottom of the head could have something to do with replacing the top half when practice versions can be used over and over again including replacement of the tail drum.

 

[BMG50]

The other question is the the difference in drum tails, some are fixed, spot welded in place with a non flare shaft compared to a flared one which has a removable tail drum which i assume is practice. The yellow tail has the 3 rivets which hold the striker assembly to the tail and the tail shaft is flush with the fins of the tail, where the other grey tail protrudes slightly out, it doesn't have the rivets, is this early late mid war? As you can see the detached tail drum with odd shape fins and the flared tube, is this wartime, post war or British post war.

 

[BMG50]

Finally it seems i have a adaptor to fit to a pineapple grenade body thread which makes the body tube longer than normal, was such rifle grenades with pineapple common as the other type later is seen with metal fingers. theres also a inner thread that hold a inner grommet that keeps in the striker what has two holes to remove it what era is this early mid late war. What is the thread sizes for the pineapple grenade and thread size to the main body of the rifle grenade tube as the threads need a clean out.