30x173


#1

What did I acquire? Plain 30x173 TP as far as I can tell. Is it missing a driving band?




#2

jestertoo,

Take a look here: viewtopic.php?f=8&t=9339&p=67186&hilit=gau#p67186

My guess is the upper driving is just missing or was not installed.

The first line of stenciling on the case reads “…MM TP-S?T”, the next to last letter is washed out can you indicate what that letter is?

AJD (stencil on the projectile) may stand for Aerojet Ordnance and Mfg. ACN (stenciled on the case) may stand for Amron Corporation.

I believe the projectile and case date to 1977 (“lot #77” stenciled on case and projectile)

Brian


#3

I also have one that is missing the forward driving band:

Mine is an experimental afterbody drag loading which had a tracer-type element in the rear to help reduce drag. Unfortunately I have not been able to determine whether the driving band was intentionally left off, or if it was removed for demilitarization purposes.


#4

[quote=“bdgreen”]jestertoo,

Take a look here: iaaforum.org/forum3/viewtopic.ph … gau#p67186

My guess is the upper driving is missing.

The first line of stenciling on the case reads “…MM TP-S?T”, the next to last letter is washed out can you indicate what that letter is?

AJD (stencil on the projectile) may stand for Aerojet Ordnance and Mfg. ACN (stenciled on the case) may stand for Amron Corporation.

I believe the projectile and case date to 1977 (“lot #77” stenciled on case and projectile)

Brian[/quote]

30mm TP-SFT


#5

[quote=“twoaz”]
Mine is an experimental afterbody drag loading which had a tracer-type element in the rear to help reduce drag. .[/quote]

That is a base bleed unit which produces a certain amount of gas while burning to fill the aerodynamically caused vacuum at the projectile base and makes up for a longer range / less speed reduction.
This system is usually used with large caliber howitzer projectiles of 105mm and larger.


#6

Jestertoo,
Thank you for filling in the missing letter.

I’ve heard of TP-S = Target Practice-Spotting/Signature, TP-SM = target practice - smoke and TP-SP = target practice – spotting, but “TP-SFT” is new to me. Can someone explain what the abbreviation “SFT” stands for? Based on the post by “twoaz” I assume the T in SFT stands for tracer.

Curiosity has set in, does anyone have information on the base bleed system being used/tested in 30mm projectiles/ 30x173mm cartridge?

As EOD said in his post, base bleed is employed mainly with much larger caliber artillery projectiles.

Brian


#7

I found this from an auction on Ebay regarding the missing front drive band:

this is a 30mm gau-8 projo from the experimental time back in the 1972 -1973 age when they were trying to come up with what we have to day for the gau-8 this one was with 1 driving band removed used in a different chamber depth than the longer types today use

http://www.gunbroker.com/Auction/ViewItem.aspx?Item=368654255


#8

This link is probably old news around here, but in case it isn’t:

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA140367


#9

How about 30mm tubular projectiles

http://www.dtic.mil/dtic/tr/fulltext/u2/b087370.pdf


#10

jestertoo,

From your first reference, Historical Development Summary of Automatic Cannon Caliber Ammunition: 20 – 30 Millimeter, on page 121, the observation of tracer projectiles exhibiting reduced drag is discussed. Further down on the same page it is noted that GAU-8 (30mm) projectiles with pyrotechnics in the base, called drag reducing fumers i.e. base bleed, were tried in the 1970’s and dropped to reduce production cost.

So from my question posted above concerning the projectile designation “TP-SFT”, do the letters FT stand for Fumer Tracer? Anyone know?!!!

Brian


#11

Brian, I don’t think that this “SFT” marking is an acronym indicating either “Fumer” or “Tracer”, because it is also found in cases which already have those characteristics indicated using their respective markings (e.g. “T” and “w/Fumer”). Could it be a contraction for “Shaft”?


#12

It is difficult to see in my photo, but my cartridge is marked like Fede describes:

30MM ADTPT
SFT W/FUMER

I agree that it would be redundant for the “FT” to indicate fumer/tracer.

There is a report on these experiments titled “GAU-8 projectile afterbody drag reduction by boattailing and base injection with heat addition”. I’ll see if I can get a copy through my local library. Perhaps the acronym will be explained there, and even if it isn’t, it should be interesting to read!


#13

I picked up a couple more rounds.



#14

Any clue what the orange round is?

Of interest,maybe, the guy I bought these from shoots them in a 30x173 sub caliber insert for their pak40.