Unknown US Fuze stamping/marking

[REDHAT6]

Good morning hive,

Since this is a fuze question, The question for the day is: What does the "NBF" on this US MK.29 fuze stand for? (I lean towards it is the manufactures initials, a foundry mark or Naval Bureau Fuze stamp or?) Honestly I not know that is, that why I am asking, for the education of our field.

Any information would be appreciated.




Thanks in advance.

 

[HAZORD]

That three-letter code doesn't match anything in the U.S. manufacturers code book. Your guess is probably as good as anything else.

What size projectile is that? That fuze isn't standard for that projectile, as the diameters and radius of ogive don't match. I've only seen that done on the 16 inch submunition projectiles, where they use an Army Mech-Time fuze to eject the grenades.

 

[MINENAZ16]

Hello,

Considering the fuze cap is missing diameter could match.

 

[REDHAT6]

I was informed that the ordnance pictured is a 4.7 inch (120mm) M73.

 

[HAZORD]

That combination is definitely not appropriate for anything. The M73 used an Army Mechanical time fuze of larger base diameter and not a Navy PD fuze. The photo makes complete sense now, since the M73 is long and tapered.


Is the assembly some kind of EOD identification trick question?

 

[Yodamaster]

When I look to the drawing of MinenAZ, I have a question to ask.
Why put a stamped marking on the base of a fuze if it must be covered by an aluminium cap ?

Are you all sure it is a Mk29 ?
Had the M48 (serie) not a Mk variant ?


Yoda

 

[REDHAT6]

Yota, Just to explain how that number was found, they enlarged the picture and you can see the Mk. # on the upper portion of the stampings.

 

[HAZORD]

The more I think about this, it may have been an attempt to convert the M73 over for use in direct fire on ground targets or long range ground artillery.

Yoda, if you look closely at the drawing that Sebastian posted, and at the fuze in the photo of the M73, you can see a slight shoulder right below the delay/superquick selector. That shoulder was most likely for the sheet metal ogive for a fuze to fit on a three inch projectile. In that case, the markings would be visible.

In the drawing, a phenolic/fiberglass wrap has been added around the standard 3 inch fuze body to make it match the larger diameter tips of the 5, 6, 8 inch and larger projectiles which are more blunt and have a different radius of ogive than the 3 inch projectiles. I always wondered why some fuzes had the wrapping. Now its becoming clear. You can see that when the wrap was added, they needed a hole through the wrap to get to the superquick switch.

 

[HAZORD]

I took a photo of an M73 with the Navy composite fuze. This is what it would look like when fired.

 

[MINENAZ16]

Nice example.

 

[REDHAT6]

Those 2 pictures explain a lot.