I recently got a new barrel for a tikka action I had chambered in 223. The barrel shoots well, but when trying a new load that wasn’t compressed, I saw a bit larger SD/ES values than I was used to when using the same components in a different 223.
This got me wondering if a compressed charge would give better ES/SD. The test is not perfect by any means, and tests two variables at once (powder compression and seating depth), but I thought I would share.
Rifle: Trued tikka T3X, 20” Bartlein 1:7.7 twist, 223, bravo chassis. SWFA 5-20x50, Sportsmatch rings.
Weather: 30-35 degrees, 28.7 mmHg, 50-60 H2O, Wind very variable running between 10 O'clock and 1 O'clock
Rounds left out overnight and kept in shade during testing.
I didn’t hold for wind. Aimpoint was the 6” plates everytime. I tried to get targets big enough to contain all impacts
Quoted wind values were based on reading an anemometer before and after strings, but I wasnt able to read it during strings of fire. Take wind estimates with a grain of salt. Wind direction is marked on targets as well.
All rounds monitored and recorded for velocity with labradar.
Ammo “N”: 77TMK, once fired LC16 brass, CCI400 primer, 24.2 gr Varget, 2.450” OAL with no powder compression
Ammo “C”: 77TMK, once fired LC16 brass, CCI400 primer, 24.2 gr Varget, 2.350” with moderate powder compression. (A lot of crunch, powder barely moves when cartridge is shaken, and no bullet deformation from seating plug).
I fired 10 rounds of each ammo at 100 yards, since I’d never tested ammo “C” for baseline.
Ammo “N” on the left, “C” on the right
I then moved to 635 yards and fired 35 rounds of each “N” and “C” as follows:
5 Rounds “C”, record data,check target.
5 Rounds “N”, record data, check target
10 Rounds “N”, record data, 10 Rounds “C”, record data check target (x3)
The wind seemed intent on being squirrely when shooting Ammo “N”. If I could go back, I would have alternated which ammo was fired first in the (2) 10 round strings.
Ammo “N”
Ammo “C”
I wish I could have done this test without the influence of wind, but I didn’t want to wait for perfect conditions, particularly since this test took a couple of hours.
@Formidilosus
This got me wondering if a compressed charge would give better ES/SD. The test is not perfect by any means, and tests two variables at once (powder compression and seating depth), but I thought I would share.
Rifle: Trued tikka T3X, 20” Bartlein 1:7.7 twist, 223, bravo chassis. SWFA 5-20x50, Sportsmatch rings.
Weather: 30-35 degrees, 28.7 mmHg, 50-60 H2O, Wind very variable running between 10 O'clock and 1 O'clock
Rounds left out overnight and kept in shade during testing.
I didn’t hold for wind. Aimpoint was the 6” plates everytime. I tried to get targets big enough to contain all impacts
Quoted wind values were based on reading an anemometer before and after strings, but I wasnt able to read it during strings of fire. Take wind estimates with a grain of salt. Wind direction is marked on targets as well.
All rounds monitored and recorded for velocity with labradar.
Ammo “N”: 77TMK, once fired LC16 brass, CCI400 primer, 24.2 gr Varget, 2.450” OAL with no powder compression
Ammo “C”: 77TMK, once fired LC16 brass, CCI400 primer, 24.2 gr Varget, 2.350” with moderate powder compression. (A lot of crunch, powder barely moves when cartridge is shaken, and no bullet deformation from seating plug).
I fired 10 rounds of each ammo at 100 yards, since I’d never tested ammo “C” for baseline.
Ammo “N” on the left, “C” on the right
I then moved to 635 yards and fired 35 rounds of each “N” and “C” as follows:
5 Rounds “C”, record data,check target.
5 Rounds “N”, record data, check target
10 Rounds “N”, record data, 10 Rounds “C”, record data check target (x3)
The wind seemed intent on being squirrely when shooting Ammo “N”. If I could go back, I would have alternated which ammo was fired first in the (2) 10 round strings.
Ammo “N”
Ammo “C”
I wish I could have done this test without the influence of wind, but I didn’t want to wait for perfect conditions, particularly since this test took a couple of hours.
@Formidilosus
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