Should a firearm transport case specification start outside?

Answer: No. The cavity comes from the load, foam and clearance, and the outside follows.

Why plus 2 minus 0 rather than a symmetric tolerance?

Answer: Cavities run small, and small blocks the load, so the band sits on the safe side.

Is 3.0 mm a fixed wall?

Answer: It is mid range: 2.5 mm in small cases, 3.5 mm in large ones, with a uniform main wall.

Who sets the stack height?

Answer: The tallest place cases are stored. If the drawing cannot meet it, mould the limit on the lid.

Can IP67 go into air freight papers?

Answer: It can be quoted, but proves dust and water only. Airworthiness is confirmed separately.

Firearm Transport Case Specifications: Size, Wall and Load

Quick answer: Write a firearm transport case specification from the inside out: cavity from the load envelope and foam, then wall and rib pitch, then static load, stack height, vibration spectrum and IP rating. Every line must be measurable.

Turning Requirements into Drawing Parameters
Internal Size and Tolerance
Wall Thickness and Rib Pitch
Static Load, Stacking and Vibration
IP Rating and Temperature Range
FAQ

1. Turning Requirements into Drawing Parameters

Briefs fail at the first line, where needs arrive as adjectives: strong, light, waterproof. A toolmaker can only guess. A firearm transport case brief turns each adjective into a number before the mould is quoted.

Requirement	Parameter	Value	Verified by
No rattle	Cavity, tolerance	900 x 340 x 190 mm, plus 2 minus 0	Calipers, 4 points
One person carries it	Loaded mass, handle	18 kg, 250 kg handle	Ten minute pull
Stacks in transit	Layers, static load	4 layers, 72 kg on base	24 hour load, set

External size comes last: cavity plus wall, rib height, latch protrusion. Reverse it and foam gets shaved to recover millimetres.

2. Internal Size and Tolerance

The cavity of a firearm transport case equals the load envelope, foam both sides and lift clearance: at 20 mm per side, a 900 x 340 x 190 mm envelope needs about 946 x 386 x 213 mm.

Firearm Transport Case: pale blue case open on a dark surface, black foam in lid and base, milled recesses and a handle pad

Parameter	Value	Note
Cavity length, width	Plus 2, minus 0 mm	Bias small
Gasket compression	2 mm	Part of the stack
Draft angle	1.5 degrees	2 in deep cavities
Internal corner	R8	Costs corner width

Write plus 2 minus 0, never plus or minus 1: a cavity errs small and a symmetric band fails one way.

Draft eats the nominal figure: over 190 mm, 1.5 degrees draws in 5 mm per side, and R8 corners take a dozen more of usable width.

3. Wall Thickness and Rib Pitch

Thicker is not stronger. Three millimetres is the working wall for a firearm transport case: 2.5 mm whitens at the corners in a 1.2 m drop, while 4.0 mm invites sink marks on flat faces.

Feature	Thickness	Spacing
Main wall	3.0 mm	Not applicable
Rib	1.8 mm, 0.6 x wall	120 mm pitch, 8 mm high
Bosses	4.5 mm	Hinge and latch pads

A 120 mm pitch with 8 mm ribs keeps the side wall from bulging under load. Polypropylene shrinks 1.5 to 2.0 percent, so the tool is cut oversize: over 900 mm the spread is nearly 13 mm, and 0.2 percent between lots costs 1.8 mm, half the band.

4. Static Load, Stacking and Vibration

Load is written twice. Static load on a firearm transport case means 150 kg on the lid for 24 hours, set under 2 mm after release. Stacking follows real layers: 18 kg per case over four puts 54 kg on the base, and a factor of two makes the validation 108 kg.

Firearm Transport Case: pale blue empty case upright on a timber pallet, corner pads on its face, rows of cases stacked seven high

Test	Parameter	Pass criterion
Static load	150 kg on lid, 24 hours	Set under 2 mm
Stacking	4 layers, 108 kg	No permanent bulge
Random vibration	5 to 500 Hz, 1.0 grms, 30 min per axis	Latches stay closed

Vibration for a firearm transport case follows the route: road freight takes 5 to 500 Hz at 1.0 grms, air freight adds 0.5 inch double amplitude below 100 Hz. State the stack height the store uses, or mould the limit on the lid.

5. IP Rating and Temperature Range

An IP rating needs a test state. IP67 is dust tight plus 1 m for 30 minutes, yet the same firearm transport case passes empty and fails loaded, or passes with every latch home and leaks with one resting on its keeper.

Temperature takes two ends and one action: minus 30 to plus 60 Celsius for storage, a cold drop after four hours at minus 25, and 48 hours at 60 Celsius under 0.3 percent growth.

Keep ingress and compliance apart: IP67 says water stays out, not that a carrier accepts the shipment.

Conclusion

A specification is a set of numbers a third party can measure: cavity plus 2 minus 0, a 3.0 mm wall on a 120 mm pitch, 150 kg over four layers, a 5 to 500 Hz spectrum, IP67 with its test state written down. Hold those numbers and the drawing holds, which is how a firearm transport case specification survives inspection and repeat orders.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.