While I have numerous AFV painting experiences under my belt I am attempting my first towed gun-the Trumpeter BS-3 100mm anti tank gun. While I have left the wheels unattached to facilitate airbrush painting, the shield and all the nooks and crannies concern me as far as getting adequate paint coverage. Any suggestions to accomplishing this?

Paint the nooks and crannies with a brush (the primer or the base coat), then spray it over. If you use black basing method, it will be working in your advantage quite well.

Gabriel

The advantage with an airbrush in this case is that you can get paint into all the corners that you can see and a few that the eye can't reach. With a paintbrush it is only possible to reach the corners that the "thick" straight handle can find a straight access line to and some extra space to be able to move the brush a little.
The drawback with the airbrush is that it is easy to get too much paint into "nooks & crannies" so go easy on the paint flow and paint it slowly so that you have control over the build up of paint.

The tedious job of painting around all the "nooks & crannies" of the lower chassis of an Tamiya Leopard 1 convinced that I needed an airbrush. From then on it was quick and easy to get the paint into all the corners.

/ Robin

Another consideration with spraying into tight corners and recessed spaces is the turbulence produced by the interruption of the air flow. This can result in a grainy finish. Consider lowering your air pressure and definitely add some retarder to your paint.

Just a thought. Plan on 5 or 6 painting seasons where you apply just a thin coat and slowly build paint density so you can prevent accidently getting too much paint when you work on the nooks and cranies.

If it's not too late, leave the cannon, carriage and shield separate until completely painted. But since it sounds like you have already assembled it, definitely go with thin light coats like already mentioned to build up good color and less chance of running or paint collecting in the nooks and crannies. Take your time don't rush.

Consideration of the build should be taken before even cutting parts off the sprue. In cases of complicated builds or open top vehicles, I clean up as much as possible the parts while still on the sprue, then paint them (again, while still on sprue). Clean up of attachement points and touch-ups done during assembly. Of course, this is only neccessary for models with nooks and crannies, and open top vehicles. All exteriors can be done the usual way.

I've only built a few towed artillery pieces like the 105mm howitzer but built the gun, carriage and shields as separate assemblies painted them then finished assembling the kit. I build AFVs the same way so something with lots of nooks like a sherman's vvss or hvss running gear I'll leave them off and paint them separately to make sure I can get everything covered evenly. Then I finish assembly and give it one final thin coat to blend everything together. Then I'll camo if needed, detail paint then weather. Some people build the whole thing 'cept maybe road wheels and paint it all in one go.

That's pretty much what I do, major sub-assemblies: turret, hull, running gear. I leave off things like tools, grab handles, antennae, etc until all the painting is done; especially if I'm doing a lot of masking for a camo pattern. I add all the knick-knacks then gloss coat, decals, gloss coat, weathering, flat coat.

At the end of the day, it is just a matter of how you feel better doing it.

Unlike some of the above, I prefer to have as much as possible assembled when painting. For example, I have painted a Flak41 and a leFH18 completely built, with shields on.

Try both ways and decide what you like most, there is not a single "correct" way.

I find that it can be useful to stick toothpicks into the holes that the pins on detail parts like those will mount to if they're not covered by masks, then clip them off very short before painting so they don't interfere with the paint. This keeps paint out of the mounting holes, and increases the durability of the glue join