.300 Blackout Subs

.300 Blackout Subsonic (217.6gr cast over 10.3gr IMR 4198) – 1015 fps / 498 ft-lbs (10.5″ barrel, 1:8 twist)

This is a semi-auto subsonic suppressed or unsuppressed load for the .300 Blackout using the NOE TL310-225-RN-CE3 GC mold. Drops from mold at 217.6 grains.

Note: Designed to reliably cycle a 2.6oz buffer with normal spring in a pistol-length gas system.

Cartridge

• Overall Length (COAL): 2.1550″ +/- .005″
• Bullet: 217.6gr, .310″, NOE TL310-225-RN-CE3 GC (no GC, PC’d) 1.369″ length
• Sized bullet: .309″ +/- .0005″ (PC and size to .309″)
• Charge: 10.3gr IMR 4198
• Fill ratio: 87.1%
• Case length: 1.360″ +0.000″/-0.001″
• Case wall thickness: 0.012″ +0.000″/-0.001″
• Seating depth: 0.574″ (0.795″ extent)
• Primer: CCI SR #400

Bullet

• 217.6gr, .310″
• NOE TL310-225-RN-CE3 GC
• Cast 90/5/5 w/w % Pb/Sb/Sn (Lyman #2 alloy)
• Water quench
• 1.360″ +/- .002″ length as cast
• No GC
• Powdercoat
• 1.369 +.003″/-.004″ length as powdercoated
• Size PC’d bullet to .309″ +/- .0005″ (Lee 309-H0)
• No lubrication

Brass: .223 Remington to .300 Blackout (on RCBS Rock Chucker)

1. Lee univeral decapping die (Lee 90292 w/ Lee SE3009 Ez X Exp decapping pin)
2. Mini cut-off saw at neck junction, deburr (Lyman universal case prep kit)
3. RCBS small base .300 Blackout sizing die (RCBS 22401 .300 Blackout die set with RCBS #2 shell holder RCBS 9202)
4.  Lee .300 Blackout case trimmer (rough, Lee 90110 cutter & lock stud with Lee 90443 case length gauge & shell holder)
5. L.E. Wilson case trimmer (finish, holder is L.E. Wilson CH-3ACC)
6. Deburr & chamfer (Burstfire annealer + Lyman case trimmer attachments)
7. Ultrasonic (Alconox)
8. Anneal (Burstfire annealer, 6s)

Loading (on Lee 4-Hole Classic turret press, Lee 90064 press only or Lee 90304 kit)

1. Lee safety prime (Lee 90997)
2. Lee short charging die (Lee 90995)
   • Weigh powder w/ Lee safety powder scale (Lee 90681)
   • 10.3gr IMR 4198
3. Lee expander die (L/R setup, Lee 90798)
4. RCBS .300 Blackout seating die (RCBS 22401)
5. Lee factory crimp die (Lee 90590)