Seeing FPS differences based on how powder was dropped

[va_connoisseur]

As the title says, I am trying to figure out a velocity issue I am experiencing. Twenty rounds loaded with 44gr of Varget in FGMM once fired cases.

So here's the deal, I loaded 20 rounds, with one difference:

(a) 10 rounds were loaded using a simple funnel (RCBS cup/funnel) to dump to charges into the case (rounds on the right)
(b) 10 rounds were loaded using a "long neck" funnel (like 4"), to dump the charges into the cases (rounds on the left)

Both groups were seated to 2.21" CBTO. However, Group A what I can only describe as a pressure ring near the top of each round. Group B did not, also there was no "crunch" when I loaded each round. There was a crunch for each round of Group A.

While the group sizes were negligible, group A was running about 25fps faster. Neither group showed pressure signs. Any ideas? Am I concerned about nothing?

 

[spife7980]

You are crunching powder which is breaking it up which is increasing the surface area which is increasing how quick it can burn in addition to packing it all tight.

 

[Precision Underground]

You are crunching powder which is breaking it up which is increasing the surface area which is increasing how quick it can burn in addition to packing it all tight.

This. And the ring is from the stem pressing on the bullet while it’s crunching the powder.

 

[Deleted member 113831]

You are crunching powder which is breaking it up which is increasing the surface area which is increasing how quick it can burn in addition to packing it all tight.

Bingo. Spife nailed it.

 

[RackOpsTactical]

The long neck funnel is settling the powder. This allows you to put more in the case or give you more air between powder and bullet. This makes perfect sense that the short funnel had crunch and the other did not.

Settling can be a helpful tool but it may allow you to over pressure so use with caution. However if you are not getting pressure it can be useful to fit more powder in with little to no compression. A tumbler can be used to settle powder by placing a case with powder on the top of it as it vibrates.

 

[AIAW]

Reloading 101.

That ring... Seating those couldn't have felt "right". I speak from experience

 

[bunsen27]

You are crunching powder which is breaking it up which is increasing the surface area which is increasing how quick it can burn in addition to packing it all tight.

The long neck funnel is settling the powder. This allows you to put more in the case or give you more air between powder and bullet. This makes perfect sense that the short funnel had crunch and the other did not.

Settling can be a helpful tool but it may allow you to over pressure so use with caution. However if you are not getting pressure it can be useful to fit more powder in with little to no compression. A tumbler can be used to settle powder by placing a case with powder on the top of it as it vibrates.

winner winner chicken dinners for both guys correct answers and an article on the effects of using a drop tube for reference:

Powder Column Height Varies with Case-Filling Methods « Daily Bulletin

Most of us assume that if we weigh our powder carefully (down to the tenth of a grain or less) we can achieve a uniform powder fill from case to case in our handloads. Weighing does ensure that the weight of the propellant in each case is the same, but is the column of powder the same by volume...

bulletin.accurateshooter.com

 

[va_connoisseur]

Thanks for the insight