Best vent hole size for BH209

[bowbender6]

I have been making my own vent liners for over 5 years using HoloChrome screws. I have been drilling them .031". It looks like the opinion is .033" is the optimal for BH209. I have some .033" drill bits and could drill them out easily. I have five .45 and 5 .50 cal guns and I haven't had any issues. What is the opinion on the
best size?
Thanks

 

[ronlaughlin]

Here is what i wrote in May of 2011.

One ventliner has a flash hole of 0.033". The other ventliner has a flash hole of 0.028"

The load was 115g of BH209 ignited by STS primer, pushing a 270g Deep Curl in a Harvester sabot.

When i purchased my clock, i couldn't bring myself to pay extra for a model that calculated the extra things such as SD. Today i was some sorry that i didn't. The 0.028" flash hole seemed to be more consistent, but i have no Standard Deviation # to illustrate this.

I shot 3 shots with each ventliner, and then switched to the other, and then switched to the other, and then switched to the other. The results are:

0.033" flash hole gave a muzzle velocity of 2010 fps

0.028" flash hole gave a muzzle velocity of 2017 fps

For some reason i never wrote down how many total shots were made.


Recently a fella had me modify a breech plug to utilize vent liners. When i sent the plug back, i included a vent liner with a 0.027" flash hole. He wrote back to say the plug/vent liner did not reliably ignite Blackhorn, so he replaced the vent liner with one with a larger flash hole. Then, he say the plug worked good. This is kinda of a mystery to me; i use the 0.027" vent liner all the time without issue.

TC factory breech plugs mostly come with 0.029" flash holes.

In Conclusion, i don't know what is best flash hole size.

 

[bestill]

.030

 

[Chick]

Here is what i wrote in May of 2011.



For some reason i never wrote down how many total shots were made.


Recently a fella had me modify a breech plug to utilize vent liners. When i sent the plug back, i included a vent liner with a 0.027" flash hole. He wrote back to say the plug/vent liner did not reliably ignite Blackhorn, so he replaced the vent liner with one with a larger flash hole. Then, he say the plug worked good. This is kinda of a mystery to me; i use the 0.027" vent liner all the time without issue.

TC factory breech plugs mostly come with 0.029" flash holes.

In Conclusion, i don't know what is best flash hole size.

Maybe that guy was using a colder primer?