25MM Bushmaster

Heavily Edited

Posted before I had all the info.
So, here are two great pics of some serious gunnage.
Originally posted requesting info on the ammo, then found the gun pic.
Gettin’ some!
That belt would look good hanging in my shop.

Does the Navy use different projectiles/warheads vs the Army?
Those are some way trashy waterways, by the way.

These look like 25x137 rounds. There is a MK 38 naval machine gun system that fires this cartridge (see http://www.navy.mil/navydata/fact_display.asp?cid=2100&tid=500&ct=2). Perhaps these rounds are being prepared for use in that system?

Several other guns fire this round, including the GAU-12 5-barrel gatling gun that was used on some Harriers.

There is a MK210 HEI-T cartridge used by the Navy, but I do not know how it differs from the M792 HEI-T.

If these are indeed being used for ship defense, I wonder if the 5 leading TP cartridges are for warning shots?

Chip - I notice that at the end of the belt, as well, there are the same blue-painted TP projectiles. Perhaps they are to warn that gun will soon be empty?

I noticed the blue tips write away and was going to ask what they were for but I really like John’s hypothesis. I wonder if you are right? Also, just curious, it is probably obvious, but why are the gunners wearing the vail type thing over there head and faces while shooting? To protect their face from hot shell cases?


Cool Pic Rick!

I like that theory too John. I actually have no idea which end of the belt is first, and I had just assumed that the TP rounds were first.

I wondered about the veils too, Jason. I just found these videos on YouTube of the gun being fired:


The shells apparently eject forward, but in the second video it looks like some of the gas from the muzzle blast blows back on the gunner. Maybe the veils are to protect them from that??

In any event, now I know what I want for Christmas!

Perhaps to test the cannon with low cost ammunition after loading.


Those hoods are standard issue (at least they were back in the 1990’s) for anyone on damage control or gunnery duties. They are made of a flame-retardant material to prevent flash burns. It is curious that the gunner is wearing one, but no gloves, and his mate is wearing a different type of hood, more like what I am familiar with.

I think that the orientation of the links suggest that the TP rounds are first in line to be fired. It’s been a long time since I saw a Bushmaster loaded, but I recall the links being “on top” of the cartridges when loaded. I do not know if the naval version has dual feed, but the Bushmaster I am familiar with could be fed (and was) from both sides, so the belt on the left could be set up for TP rounds first, left side feed, or TP rounds last for right side feed, or just the opposite depending on which side the belt is loaded into!


My theory doesn’t stand up. I was looking at the picture without my computer glasses on, a big mistake, and thought that was all one belt, with the curve simply out of the picture. I see now it is two separate belts, and each has the blue-bulleted rounds at only one end. I thought they were at both ends, as I was concentrating so much on the projectiles that I didn’t notice the belt ended in the hands of the sailor on the left. I thought it went right past his hands and curved around and went back (out of the picture), since the projectiles were so oriented that it could have been the case.

Well, there you have it. Not only dumb but blind as well. I love getting old!

Forgot to mention that my theory came from some of the .30 machine gunners and BAR guys in the Army, who liked to have about five tracers in a row at the end of a belt to tell the asst. gunner that the belt was running out and to have another ready, or put two or three in the bottom of a BAR mag for the same reason. I guess that’s “ideal stuff” that gets canned quick in real combat, where you shoot what’s available.


In my navy days it was standard practice to use a muzzle cover to protect the gun bore whilst awaiting action. The 40mm Bofors and 20mm Oerlikons used thin rubber caps which were designed to be shot through. However even this thin obstruction risked a premature burst at the muzzle as the fuze struck it so the first couple of rounds were always inert projectiles. Why five in this case, I don’t know?



THAT’S expertise. Great input.


Just found this. Interesting due to competition among shipboard divisions, generally, and helps explain some processes. TMs were/are probably pi$$ed. Sad to be them. 'Twas a great rate.


[quote=“slick rick”]Gravelbelly:

THAT’S expertise. Great input.


I just thought of something that looks strange in some of the film footage of the 25mm gun firing. Why is the man on the right of the gun having to paw the empty links out of the mechanism, looks like a sloppy feed design?


Or bad setup. The M2/3 Bradley Bushmaster manual has 100+ pages dedicated to the feed mechanism. Lots-o-parts, to say the least.

On another side-note, the 25MM Bushmaster is replacing the 40MM Bofors on the AC-130 Gunships. They’re being “re-rigged” as we speak. Got some info on the original AC gun systems, if anyone is interested.
EXTREME detail. Sadly, the limited ammo info relates to stowage racks and such, but interesting. Would make $5000 toilet seats look tame by comparison. Here’s a taste:

Not quite; it’s the Bushmaster II in 30x173 (or the marinised MK44 version which has replaced it in production - I’m not sure which). This is replacing both the 40mm Bofors and the 25mm GAU-12/U.

I stand corrected and enlightened. Hard to get specifics from the folks I spoke with about it. I think they tell me things in simple terms that they hope I’ll understand. I assumed it would be a different system designation due to mounting and ammunition variations. Anxiously awaiting “TMs” on the conversion and will add them to this post when received.