Load development w/ popple holes (9mm Major)

[TangoShooter]

Hi to all,

I'm fairly new to open handguns, have ordered one from a german gunsmith.

While I work in my loads I wondered what this "popple holes" are for (Don't have one on my gun - additional comp?) and how they effect my load development?

Thanks.

[a matt]

9mm stay away from the popple holes. .38 that's ok the act as a comp. weak comp but a comp all the same.

[kneelingatlas]

The term "popple hole" referrs to ports drilled in the barrel, compensator ports are more efficient, but the barrel holes provide a little extra resistance to muzzle flip.

The trouble with these holes is that they bleed off gas while the bullet is still engaged in the rifling, so the reduce the velocity; there is no universal answer to how much, but it still has an effect.

[Desmo412]

I had 2 1/8" holes added to my open gun after shooting it for a year. Gun has a 5.4" Schuemann barrel and Cheely Comp in 9-major. Load before the holes was 9.1gr HS6 under a MG 115 JHP at 1.165 for a 175PF. After the holes, the same load made a 173PF. I upped the charge to 9.3 grains. They made the gun recover MUCH quicker....I will definitely have popple holes in all future gun builds.

[kneelingatlas]

I chrono'd my first gun with a hole in it this weekend and it shot much faster the expected. Experimenting with holes I didn't want to drill too many and destroy the top end so I just drilled one now I wish I had chrono'd before to get a baseline because this 4.75" Tanfoglio barrel with one 3/32" hole shot the same velocities as my 5.1" CZ barrel.

With so little detriment I plan to drill two more holes, I'll be interested to see the effect on velocity.

One day I plan to make a chart to extrapolate the effects of different variables in reloading: barrel length, popple holes, OAL, bullet weight and charge weight.