Safety Warning for Berger 77 grain OTM: Pressure Testing Update

Great post. I know this is an old thread but it’s got me scratching my head. I use this exact bullet on the short lines in XTC matches with 24.7 grains of N140 in a wide variety of cases some 5.56 some 223 rem and I don’t even get the slightest sign of overpressure. My 600 yard load is lapua cases with 24.3 grains N140 behind a 85.5 Berger. Things that make you go huh 🤔
 
Great post. I know this is an old thread but it’s got me scratching my head. I use this exact bullet on the short lines in XTC matches with 24.7 grains of N140 in a wide variety of cases some 5.56 some 223 rem and I don’t even get the slightest sign of overpressure.

As Berger refused to provide me with any of the data that I requested, we’ll never know for sure what powder was used, but I don’t think it was N140. As you noted, people have been using higher charges of N140 for 77 grain OTMs for ages without any issues. The Sierra manual lists a max charge of 24.5 grains for their 77 grain bullets.

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Just tested loads with 23.1 gr AR-Comp & the 77 Berger OTM last week in 3 different guns, 3 different barrels.

No visible pressure signs on any of the brass, virgin 2019 LC with Wolf Mag primers.

I did not chrono this load it, but 22.9 grains of AR-Comp with the same brass/primer & 77 SMK's has done around 2730'ish previously.

Just a rough measurement of the bearing surface of the Berger & an SMK shows them to be very close to the same; no idea about the hardness level of the bullets themselves.

MM
 
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