Chinchaga Bullets

Dale. Janzen passed away July 31, 2026. This notice has been posted by his sister, Judy Janzen. If you want any more information, please send me a message on messenger.

Some ballistic coefficients for 257 caliber bullets and muzzle velocities at which data was recorded
257/180 2600fps G7 0.358
257/163 2666fps G7 0.328
257/150 2761fps G7 0.337
257/141 2745fps G7 0.332
257/135 2909fps G7 0.300

Stability twist requirements:
257/180 (1:7” twist)
257/150, 163 (1:7 twist)
257/135 (1:8” twist)

Test r***e 1:6 twist Jury barrel Red Deer, Alberta. Chambered 257 SAUM. Bob Galloway, Rocky Mtn House (Custom GunWorx) chambered it and threaded to a Pierce Precision Receiver.

Please post any questions to my email:
[email protected]

Not tested yet:
257 cal 150 GR. Length 1.563”,
1:7.5” will stabilize, 1:7.0” will be better.

Working on 257’s again. Reamer was designed for 257/135-145’s. It should work okay with 257/185’s. Shown alongside 308W cartridge. Have 1:6.0” twist barrel waiting for receiver. 1:7.5” twist shows borderline stability. 257/185PP is 1.695” long. 257/180OT measures 1.700”. Cartridge is 300 WSM, ran fully into 300 SAUM, then necked down in 257 WSSM.

375/430ST bullet. Heaviest 375 I can make. Needs at least 1:10 twist. Length is 2.153”, Boat tail is 0.348”, nose is 0.887”, bearing surface is 0.918” G7 BC 0.564

375/300ST bullets. 1.727” long, bearing surface 0.487”,
nose 0.887”. Needs 1:12” twist or faster. G7 BC 0.384

Terrible day, have to send these 308/210ST bullets to a customer, when I should be sending them downrange. I’m going Monday!

Equipment to measure and verify BC numbers has finally arrived. Will be testing all bullets in the next few weeks.

308/215 Grain. Length 1.485”,
Boat tail 0.190”, Bearing surface 0.642”, nose length 0.653”. Open tip.