Top to bottom) 23mm NR/NS-23, 30mm ADEN, 20mm Oerlikon, 50cal M2/M3, 7.62mm Browning. Just thought I'd share a bit of my collection to give food for thought on actual sizings of rounds,
11.4018.012.005 RockShox Top Cap Assembly Air 30 mm 30 Gold A1
A-10'un ölümcül silahı: GAU-8 30 mm top | Tolga Özbek
5mt Top Quality 1.25" (30 mm) White Flat Elastic: Amazon.co.uk: DIY & Tools
Top Zastava 30mm za oklepnik LAZAR II 8×8 | Spletni portal obramba.com
11.4018.012.005 RockShox Top Cap Assembly Air 30 mm 30 Gold A1
Square Tube End Cap 30 mm | Aluminium Warehouse
Ride 603 Cigar Storage Tube (30 mm Shell casing) Gold or Silver Top Ch
Stainless steel 30mm ring - Bimini Top Nàutica
Soldering nozzle for TOP, 13 x 30 mm - Weidinger.eu
Stiže 'pravo' oružje za hrvatske Patrije: Izraelski top 30 mm i rakete Spike! - Večernji.hr
Aimpoint Base and Top Ring 30 mm - Optics-trade
One pair of Top Hat Reducers - 31.75mm External to 30mm Bore
BRAND® stopper red rubber, H 30 mm, top diam. 32 mm | Sigma-Aldrich
File:Protiletalski top 20 mm Flak 30.JPG - Wikimedia Commons
BIMINI TOP SLIDE 2 PART A4 FOR TUBE 30 MM PART NO 8478430 – Gib Yachts Chandlery
Top Sedgwick 175 x 65 x 30 mm Bore Limiter/ Rebate Combi Head
Jason Industrial 640-8M-30 HTB Profile Timing Belt, 8 mm Pitch x 30 mm Top Width x 640 mm Outside Circumference, 8 mm Tooth, 80 Teeth: Amazon.com: Industrial & Scientific
Mild Steel Table Top CNC Profile Cutting Machine, Thickness: >30 mm, Rs 700000 /piece | ID: 21301758212