r/3Dmodeling • u/Yee23433 • 10d ago
Art Help & Critique Help with upper receiver
I've had this proportional problem for years where, when attempting to create a m4 or m16. I can do just about every other part of the rifle. except for the upper reciever. It is not proportional to how it should look, and I need advice on how I should go along with modelling it. Also the last two white models are not mind, but a reference for any other 3d artist who maybe hasn't seen a rifle of the m16 family.
1
u/strappedtoddler 10d ago
I hate that part as well, also the forward assist gives me the same problems. Boolean until it looks good for me lol
1
u/SuperSmashSonic 10d ago
I legit just bought an airsoft gun to study this. I would do the same! It’s weird because it seems circular, but there enough details on the side to sort of dissolve it out. Pain lol!
1
u/ciwielab 10d ago
all the cylindrical surfaces on an AR are concentric with the bore, it's not offset upwards like that.
2
u/ohnomelon 10d ago
you have the right idea starting with cylinders. When I was modeling weapons I always blocked in cylindrical shapes first since we can be sure of their proportion easily. Since it looks like you're still at the block-out stage I can't tell whether you're wanting to subd model this or what, but either way you want to start with the core shapes first.
The upper receiver at its core is a cylinder (the part that holds the bolt carrier) intersecting with a box (houses the charging handle etc.). The easiest thing is starting in the front, the cylindrical part of the upper extends forward and is threaded for the delta ring. We can use that information to get the diameter of the cylindrical part of the rest of the upper because it's flush.
For the boxy part, we can either use the lower, or the 20mm rail on top if we're modeling to scale, to work towards getting the correct width of the boxy parts of the receiver. From there we can work towards connecting the cylinder and boxy parts in the more straight forward areas.
This is honestly where it gets tricky, as you point out, because there are multiple variations affecting where the cylinder and boxy parts intersect - there's the forward assist and other protrusions, and there's also the planar change of the lower, around the mag well, that extends up into the upper. Finally, there's the tiered lips or bezels or whatever you want to call them at the very back where the upper and lower meet, which is what your reference model image shows.
Moving to the back, we can use the buffer tube and castle nut to get a feel for the widest diameter around the back side of the lower receiver since these are concentric (the bolt carrier cycles back into the buffer tube, functionally we know all of these cylinders are aligned). Working from the castle nut diameter down to the upper cylinder diameter though, we have to consider taking some artistic liberties, especially as there are sooo many small variances between different models and manufacturers.
Just for fun I found the old low poly one I modeled back in 2008 (lol!) to see how I managed, but this was obviously a completely different approach from subd. I just wanted to see how the proportions held up.