I put some factory Remington 300 Blackout 125 gr OTM through my SSK 300 Whisper to see how different this ammo really is. I disassembled five random cartridges from the box. The composites were weighed.
The bullets weighed 125, 124.9, 125, 125, and 124.9. The bullets resemble a Hornady 225 Match with the back half cut off. They have a little less curve in the ogive, but they both have a compound ogive. They are consistent and well made.
Hornady 225 300 Whisper on the left 125 OTM Blackout on the right
The brass weighed 85.3, 85.1, 85.7, 85.6, 85.8. The cases are lightly crimped and the necks are annealed. One piece of brass was completely annealed. That case will be discarded. Case lengths were 1.361, 1.3615, 1.3595, 1.361, 1.361. The AOL of the cartridges is 2.227. The unfired brass is dimensionally identical to factory 300 Whisper brass and the 300 Whisper brass I make except the head stamp and trim lingth.
The powder charge was 18.7 gr of unknown powder that resembles one of our favorites.
The chronograph was not cooperating today so the test is not complete. It was very windy and kept blowing the sky screen over. I did run three shots through the gun.
The cartridges that were unloaded were neck sized and reloaded back to factory spec. The only difference was that I charged it with 18.7 gr of H110. I will shoot these through the chronograph next to the factory loaded ammo.
Threaded Mode