This is more a documentary of my personal evolution. I am not an instructor, "expert", or Holiday Inn frequenter, and would be happy to hear how I can improve. That said, a big reason for my fumble on the live drill is I loaded the shot card mixed, when I typically leave it all slug. It tripped me up. Normally, its all buck in the gun, and all slug for select slug on the card.
I’ve done the homework, here is the pricing for $138 list:
99 USD value (under the $100 ATF limit) Minor Firearms Component M4 6 Position Recoil Tube (Customs Label “Shotgun Accessories” HST Code 9305.20.80 Found in Chapter 93)
$39 USD Value for 5 pack internal retaining springs (Customs Label “Screws Nuts and Bolts” HST Code 7318.13.00 found in Chapter 73)
$20 shipping and handling is extra
Got the initial prototypes today, scheduled for production in about 3 weeks… slides very nice and is tight on the notches. Complete with “drain holes” for a punch to get the spring out. some surface finishing aspects will be improved for final run (even though these look pretty good).
the wall thickness is so thin in some areas I may not be able to do black nitride. At least not a full bath (usually 90 minutes). I might do a short bath of 7 minutes or so to at least get a microscopic layer of corrosion resistance, then hot black oxide after. I’ll post more pics once I get it on the gun and do some function tests.