Interesting observation

Varmint Hunter said:

In my endless effort to find the perfect load I observed something interesting.

I loaded 9 rounds of several different loads to be tested. This would allow me to fire 3 - 3 shot groups of each load. I shot the groups in a round robin fashion.
First group of load #1 - then first group of load #2 - then first load of #3 and so on. Eventually I'd get back to load #1 again to retest that load. This would allow the groups to be fired under different bore conditions.

I fired 6 fouling loads the day before the tests began. Everything was chronographed with the Garmin.

The two things that I noticed were:
1. Velocity of each load continued to rise throughout the testing - not dramatically but noticeable
2. Fouling conditions definitely affected group size. Virtually all the loads shot the tightest groups on a relatively clean but fouled bore. Groups did open as the barrel accumulated more fouling.

FWIW - I was shooting a custom 6.5PRC with a 23.5" Bartlein carbon bbl.

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VinceMule said:

Wind conditions change. The atmosphere heats up from morning till noon.

Wind has more to do with group size than most would ever like to imagine, yet few if any ever put out a wind flag. If you do not have a wind flag, you are shooting blind.

This is all I will say for now.

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VinceMule said:

Wind conditions change. The atmosphere heats up from morning till noon.

Wind has more to do with group size than most would ever like to imagine, yet few if any ever put out a wind flag. If you do not have a wind flag, you are shooting blind.

This is all I will say for now.

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Varmint Hunter said:

Fortunately, it was a dead calm day with no wind or heat mirage to speak of. Our club has wind flags out that are permanently mounted. We have flags at 200yds-300yds and 400yds. I was shooting at 400yds.

I rotated three guns and never shot with a hot gun. It was 50deg when I started shooting. I use a cordless mattress inflator with a surgical hose to blow ambient air through the barrel between shots 2 and 3, and then the rifle is set back into the rack while I slap steel with other rifles. Barrels are barely warm to the touch when I shoot the next 3-shot group.

On average - I'd say that velocities increased about 20fps from the first group of any particular load to the last. They increased incrementally from the first to the last.

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memtb said:

I think that a steel ring when heated, shows an increase in hole diameter. Perhaps the barrel interior diameter is getting "slightly" larger….giving less drag/resistance in the bore! memtb

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Beluebow said:

What increments were your three test loads?

Round count on the barrel?

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Phil Rizzo said:

I have tried 2 other manufacturers since my last Bartlein was installed, out of 3 I had in service.

Without getting too specific I can assure you of this Paison, I'm not going back.

Never owned a CFW Bartlein, these were SS. But I know of at least 2 that were returned because of QC issues, acknowledged and replaced. Eventually…

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Varmint Hunter said:

However, a Bartlein bbl should be smooth enough to resist fouling.

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Varmint Hunter said:

Loads were not incremental. I was testing proven loads with various powders to determine which was best overall.
Barrel has about 500 easy rounds on it.

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