Compressed vs non-compressed powder test

Stu

Lil-Rokslider
Joined
Dec 29, 2019
Messages
223
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
6C82DF75-4DC4-4752-83F3-BA11E68E090C.jpegFEC556C1-F052-4560-A4B4-A4C786123232.jpeg

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”529A6511-1E28-4749-92D5-EC1A3676AB97.jpeg

A08DB03F-71F2-4E71-8CF0-3B943343851B.jpeg

Ammo “C”
982F98DD-063A-4F2B-804B-5219E4B2B440.jpeg

184D39D6-D279-4EFF-9BC8-88F7E61ADA26.jpeg

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
 
Last edited:
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Stu

Lil-Rokslider
Joined
Dec 29, 2019
Messages
223
Truth.

Just think if I'd only used one pair of ten round groups and drew a conclusion. I'd say you're onto something with the statistical nonsense, but you're only a sample of one.
 

Formidilosus

Super Moderator
Joined
Oct 22, 2014
Messages
8,017
Truth.

Just think if I'd only used one pair of ten round groups and drew a conclusion. I'd say you're onto something with the statistical nonsense, but you're only a sample of one.


Haha.
 
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