Flash Hole Diameter-----Velocity

[ronlaughlin]

Kinda did this comparison once before; today was the day to double my knowledge by doing it again.

What i did was shoot the load through the chronograph; remove the breech plug and change the vent liner, re install the breech plug, reload, and shoot the load through the chronograph. First shot used a vent liner with a 0.034" flash hole. Second shot used a vent liner with a 0.028" flash hole. Third shot was using the 0.034" vent liner; fourth shot used the 0.028" vent liner etc. The tenth to thirteenth shot just used the 0.028" vent liner. The clock was located at 27 yard out. The target holder was at about 100yd. Ten shots at one target; the last three at the other.

The V2 was used for this shoot because the QRBP made this vent liner switching not so tedious. Sight was a 4 power scope. Load was 270g Deep Curl, 110g BH209, green Harvester sabot, STS primer. Temperature was about 27 degrees. Elevation was about 4700'. Breeze came and went.


Speeds at 27 yard.

[MountainDevil54]

There was another guy on a forum that used an 1/8" FLASH HOLE and picked up an extra 300 FPS. Needless to say that after i told him what the fudge were you thinking? He went and bought a new breech plug

[ronlaughlin]

Did some more clocking today. The load was the same as yesterday, as was the rifle, and the method. The clock ended up a little closer today; about 14 yard.







This time the smaller flash hole produced the higher velocity, and as before it isn't significant.