Thanks for the comments!!  Thats why I posted it, thought it was worth some research!!  The 61' could possibly be a year reference.  Have you ever seen original WWII Marine Raider patches? These look worse then the supposed clown on the back of the helmet.  Hopefully you don't own these!!!  Lol!!            

Machine Gun Detachment Cavalry Puerto Rican Militia is my guess.

Recently acquired them. Not recently made. 

“Clown adjacent”…. 😂   That is money.

Here is my early Nam advisor period about 4 years ago. 13 star-buttoned 107's, 51 field cap, with Okinawa Boots.

Can anyone decipher this?

Added this SE EBY to my collection 

M1917 Light Tank.  

I do not see any connection to the Raiders after reviewing the photos and apparent research. The target being an accentuation of apparently isolated battle damage is also a bit too far fetched for me. 61' as painted would indicate a year more than any association to a unit and the sideways swazs with flames? coming out of them are not serious with deeper meaning. A skull on the back that's clown adjacent just doesn't scream "Marine Raiders from 20 years prior." This just looks like a potential veteran or even motorcyclist who was at or near Quantico in the 1960's who painted up a helmet for his kid to play with.   There's zero indication this would have any notable ties to the Raiders.