HobbyBoss M4 High Speed Tractor (155mm), WIP

Here I’m back again - sorry that it took so long, but Real Life is 35 times bigger than the model …

Unsystematic builder that I am, I turned to the ammo box and installed the Hoist Guide Tube. It’s a piece of 3mm metal tube from my spares box but otherwise unknown origin that allows the Crane Pillar to slide up and down. It is drilled through horizontally so the pillar will be supported by the lock pin, shown as a shirt pin in the dry fit photo.

And once again, research led to a problem: All box walls are topped with tubes, and these tubes meet at right angles. Not so in the kit: here, the side walls protrude over front and rear walls so that not only is the seam away from the corners, but the tubes overlap, too, instead of forming an angle. Incorrect and ugly. At first, I thought it would be sufficient to drill out the tubes on the side walls, but then I looked at the prototype photos and decided NO.

The kit tube representations are 1mm diameter, so I’ve cut fitting Evergreen rod and made the necessary four angles, but trying to fit them appears to produce tons of puttying and sanding, so I consider cutting off the tubes completely and replacing them:

That consideration alone will keep me busy for a while, so please bear with me.

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With painting of the ammo box drawing nearer, a question has come up:
As we’ve all learned, the interiors of closed military vehicles are painted in bright colors like white, silver, seafoam green… With the exception of doors and hatches that would attract aerial attention showing their bright inside when open. And here’s where I’ve stumbled when seeing the inside of M4 HST ammo box doors painted white in US Army photos shown in the Ampersand HST book - was that general practice in the artillery, was it continued after WW II, was it kept up with later ammo transport vehicles, maybe even today?

Ok, got the new “tubes” mounted. Correcting the overlap of the side walls also allowed correct positioning of the tiedowns on the corners. Note the drilled out tube ends on and next to the hatch.

But I still don’t know what color the hatch inside will have to be, OD or white? Help!


Love to give you a definitive answer, but I just do not know. Given it is not a frontline vehicle, white is not a stretch. Why white and not OD like the rest? Can’t say. I do know some countries don’t paint base colours inside stowage compartments.

You are doing a great job on this M4 HST. I have the two kits in my stash and have book marked your build.
To answer your question, anything seen from the air is the same colour as the out side if you remove the tarp and not put it back on you will have a big box painted white nice for enemy plane pilots to spot it.


I was going to say the same thing - you can’t have anything visible from outside being white.

Peter, Ralph, Lee,
like I said in my post before I mounted te “tubes”, I fully agree that any open box on a military vehicle should be painted in a less obtrusive color than white - but all photos I could find of the box in question show it in white. David Doyle even captions (in Ampersand’s “High Speed Tractor”, p. 49): “Curiously, the inside of the tailgate is painted white; usually in U.S. Army practice, the insides of doors were painted the same color as the exterior of the vehicle.” Now who am I to doubt him - white it is (as long as Frenchy doesn’t come up with evidence to the contrary)!

Having puttied the positioning lines for the shell arrester board fixing mechanisms (above, 5 may), I now try to figure out how these “clamps” function: Apparently, the PE triangles are fixed to the separating walls, all at the same level no matter what caliber ammo is carried. The perforated boards rest on them and are arrested by contraptions that seem to look a lot like the thing I cobbled up for the swivel crane, see above, 3 june. The question being how the upper (in the kit: plastic) parts are installed and how they connect to the triangles. In this context it’s also questionable how the “boards” can be installed with the fixing parts in place. Their lateral slots seem narrower on the kit parts than in the photos I’ve seen. Any suggestions?

Thanks in advance, Peter

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Being a certified paintophobic, I constantly search for details that I can improve or add with the kits I’m building, thus procrastinating the dreaded painting session. Case in point: Although I still don’t know how the “clamps” work that I mentioned in my previous post, I found a way to detail them by cutting and filing in a notch that would be there if they functioned the way I guess they could. Another day of deferment won …


Just to commiserate with you Sir - you are not the first to travel down the path of the HST and I am sure neither of us will be the last.

Great build you have going here!

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Thanks for the tip on the Archer “Generic US Placards”. Good to know!

I will be ordering some of those in the very near future!

You are not the only Peter in the “Painting Procrastination Pack”… Give me a build any day.

That is some attention to detail there.

Michael, about time you got back to that. I was watching your thread on it too!

The model is much closer to being finished now but I forget where I left off, coverage wise, in the archives.


Found it – Original post started by “raffrecon”
Link to the archived page:


And also some slightly more recent photos of the model shown then:

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Peter, Mike,
Thank you for your kind words and the compassion!
Actually, I had studied the raffrecon report for my build - looking forward to further development.
The “Generic US Data Placards” are Archer #AR35210 and worth every penny.

Re: Question regarding the Voltage Regulator on the HST:

"Hobby Boss M4HST engine room question . . . . "

Here is the link to that earlier discussion:


Again, my apologies to all as I know I am coming a bit late to the party here.

The Voltage Regulator on a US WWII Jeep as seen here:

Mike Koenig Photos

It appears that the inside surface of the ammo box door was originally white. (First Photo)


Picture 1aaaaa
(Photos please credit Ampersand Publishing/David Doyle Books -
Third photo credit ~ Unknown)

That third photo is interesting in that it shows the triangular lateral arrester bases at different heights, just as HB has given them - maybe they constructed their kit after this prototype sample? Which would leave the question unanswered why two different types of projos should’ve been carried in one vehicle.

Apart from that, this photo has no doubt been taken long after the M4 HST saw active service, which is why I’m not convinced by the OD inside - and the question remains why there was white paint in the first place, and for how long. Any takers?

And an interesting photo walkaround of a restored M4 HST of former Austrian service, for detailing freaks:

Unfortunately, no answers to the questions raised here …

Not really an answer, but it seems to me that some Ordnance pics I’ve seen of kit being tested seem to have white hatch interiors etc where logic suggests they should be OD to avoid compromising camo safety when open - could it be that under test (and photography) they wanted good detail visibility? Then the “production” vehicles would come off the line with OD instead… Just a thought!

But a very persuasive one, as all the pics showing white insides are courtesy of the US Army and have obviously been taken under laboratory conditions. What do the experts think?

And here’s another puzzling bit of information: David Doyle’s Squadron book “Long Tom gun in action” on page 74 shows a photo dated 13 august 1951 in which the ammo box’s inside is clearly painted white, and so is the inside of the open hatch. (The gun hitched to the HST here appears to be a 155mm howitzer, but I don’t think that made a difference regarding the color of the paint.)

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