40mm Hughes Lockless

Recently added this fantastic 40mm Hughes-Lockless display round to my collection and I am looking for some further information on it.
I am familiar with the more typical rifle caliber Hughes-Lockless cartridge but did not know this massive 40mm variant existed.

The body is made out of a hard clear plastic that has yellowed, marked “HUGHES U.S.A.F. 40MM LOCKLESS” on both sides. It can also be disassembled by sliding the 2 side panels down and out of the dovetail joint. The 2 halves can them be pulled apart revealing 2 black foam inserts to represent the 2 main powder charges, with the smaller primer charge directly below the projectile made from extruded plastic. No primer as it was probably lost long ago.

The projectile seems to be a WW2 era 40mm HE-T projectile, painted red with a dummy fuze plug and a solid steel plug screwed into the bottom of the projectile. The very nose is marked “DNP-5”, drive band marked “MK2 1-1 LOT1416”. Tracer plug marked “434055C” with a nice Hughes “H” stamp.

Compared with a 20x102mm. Lucan, it’s quite the brick! Any further information would be greatly appreciated!



Great item. Thanks for sharing.

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Excellent find! Pictures are great, thanks for sharing.

The 40 mm encapsulated was made for a program sponsored by the Air Force Armament Laboratory, Eglin AFB. This configuration allowed a 136% increase in energy per pound of ammunition over the standard 40 mm Bofors with no increase in cartridge volume. Firing was done with a single shot test figure using a standard Bofors barrel.

Primer used was a .50 Cal. No. 35.




Fantastic info Fede, as usual!

So this gun was sponsored by the USAF but was it meant as an aircraft armament or as an AA gun?

Also time to find a primer too!

Rhys, could you tell the exact “case length” of this one?

Wow! That is amazing.

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Alex, the case is exactly 9” / 228mm long.

Rhys, thanks a lot! This rounds up the images and basic data for this one.
Thank you for sharing this one with us.

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Of course, my pleasure!!

Certainly one of the more unique items I got recently, and I will have a few more to post soon as well.

Eglin was interested in the lockless gun concept for aircraft guns because of the advantages of weight reduction, space utilization and cost. Since this happened in the early 70’s, I think someone may have considered using this system in the AC-130 aircraft. That would have been impressive!



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Fantastic Fede, thank you very much!

I figured it must have been an aircraft armament but thought it was quite large. Something like an AC-130 makes much more sense however.