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MS21250H06034 12-Point Flange Bolt — 180 KSI, .3750-24, 2.125" Grip (Drilled Head)
MS21250H06034 12-Point Flange Bolt — 180 KSI, .3750-24, 2.125" Grip (Drilled Head)
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The MS21250H06034 is a high-strength 12-point external-wrenching flange bolt designed for tension-critical aerospace structures — airframe joints, engine mounts, rotor and control-system connections where 180 ksi tensile performance and positive wrenching engagement are required. Its flanged 12-point head delivers high clamp force in confined spaces where a standard hex cannot develop sufficient torque. The drilled head accepts safety wire for positive locking in vibration-critical installations.
Specifications
| Part Number | MS21250H06034 (supersedes to NASM21250H06034) |
| Thread | .3750-24 UNJF-3A per MIL-S-8879 |
| Grip Length | 2.125 in (±.010) |
| Overall Length | 2.770 in (±.015) |
| Head Diameter (A) | 0.639–0.649 in |
| Shank Diameter (B) | 0.3735–0.3745 in |
| Flange Diameter (W) | 0.4375 in |
| Head Height (H) | 0.388 in |
| Thread Length (T) | 0.625 in ref |
| Ultimate Tensile Strength | 180,000–200,000 psi |
| Double Shear Strength | 23,900 lbf |
| Tensile Strength (min) | 17,100 lbf |
| Material | AISI 4340 alloy steel (4140 / 8740 / 6150 alternates) |
| Hardness | HRC 39–43 |
| Finish | Cadmium plate + chromate per QQ-P-416 Type II Class 2 |
| Head Marking | MS21250 + manufacturer's code |
| Procurement Spec | MIL-B-8831 |
| Head Drilling | 4 holes × 0.037 in (±.005), equally spaced |
Datasheet & Compliance
| FSC | 5306 (Bolts) |
| NSN | 5306-01-262-6732 |
| ECCN | EAR99 (no license required for standard export) |
| Schedule B | 7318.15.8085 |
| Net Weight | ≈ 0.111 lb (50 g) per piece |
| MOQ | None — order from 1 pc |
Manufacturer certifications (CoC + mill report + dimensional report) ship FREE with every lot.
Alternatives & Related Parts
- Undrilled variant: MS21250-06034
- Same diameter group, other grip lengths: 0.250"–6.000" grips available
- Current standard: NASM21250 (military adoption of MS21250; fully interchangeable)
- Not for new design after 4 Dec 1980 per the standard — replacement-in-kind only; we support all legacy fleet demand.
Lead Time
Made to order — ships in 4 weeks. Raw material (AISI 4340 bar) is stocked at our Kunshan plant; every lot is machined, heat-treated, plated and inspected to order. No stockouts, no minimums on standard sizes.
Quality Documentation
Every lot ships with: Certificate of Conformance (CoC) · mill material report (heat-lot traceable) · full dimensional inspection report · First Article Inspection (FAI) on request. 100% thread and plating verification per MIL-B-8831.
Shipping & Duties — DDP
Free express shipping on orders of $300 or more; a flat $49.99 courier charge applies to smaller orders (FedEx/DHL, 3–7 days worldwide after the 4-week production lead time). US import duty and Section 301 tariffs are included in our prices — delivered duty paid, no customs surprises. Larger programs (>500 pcs or >$5,000): request a quote for FOB terms and volume pricing.