Flash Hole uniforming

[nicholasjohn]

I use the primer hole cutter with my RCBS Casemate and it does a good job on most all brands. But I do not use it on Lapua brass because they are burr free right out of the box.

They must be drilling their flash holes. I have read that Norma also drills them, and most of them didn't have any burrs in them. I once had a bunch of Norma 6.5 X 54 Mannlicher cases, though, that had pretty big burrs in them. I cleaned them up with a Sinclair de-burring tool, and have made this operation SOP ever since, regardless of who made the brass. I actually quit looking at flash holes to see if they need it or not - I just de-burr them all.

 

[jpndave]

Interesting, I'll scope a few tonight as well.

 

[30BR]

21st Century makes the coolest flash hole reamers... Especially for small primer flash holes which can be undersized from some mfg. (May not be an issue for hunting rounds...) You can just tickle the hole to take off the high spots. Opening those up to std hole dia. typically worsens groups, so you need to be using the smaller diameter pin for decapping. That's why I always de-cap small primers with a Redding decap die; I pull the pins on my forming dies, or replace them.

 

[Savage 12BVSS]

I actually quit looking at flash holes to see if they need it or not - I just de-burr them all.

That's my feeling exactly make em all uniform.

 

[Oddbod]

Tried taking a photo down my Hawkeye borescope but couldn't get a usable image.
So: New in the bag .270 Win brass has small pieces of brass sticking up in places round the flash hole in some but not all cases.
Cases prepped with the Lyman tool have a small, uniform chamfer.
Checked some of a mate's once fired brass (Remington factory ammo) & there's no sign of any brass sticking up - perhaps the heat of ignition on such thin pieces vaporises them?
I guess the only way to tell is by loading a case I know has brass sticking up, then firing it to see if they're gone afterwards.

 

[JAYgs8163]

I've used the Lyman tool for over 10 years and actually recorded SDs in a few different loads. SD was dramatic change after uniforming. Most of my testing was done with a 308. I actually did it on my 6.5x47 Lapua with the Lapua brass but very lightly. It did make a difference there as well for consistently lower SD. I do it all the time now. Just differently with better brass.

 

[Ol' Red]

This is an interesting thread. I have been reloading for years and never uniformed the flash holes. After seeing these pictures and hearing about SD improvements, I guess it's about time to start.

 

[30BR]

... Most of my testing was done with a 308. ... I do it all the time now. Just differently with better brass.

That's what got me started too. Shooting NRA High Power with Winchester & Lake City brass, it was the one step I added to my reloading that made an immediate improvement.
Lapua brass, I don't usually touch unless its just to make sure there are no burrs.

 

[okie man]

This is an interesting thread. I have been reloading for years and never uniformed the flash holes. After seeing these pictures and hearing about SD improvements, I guess it's about time to start.

as long as you don't go to deep it's a step that won't hurt your goal to more consistent ammo !

 

[Sod Farmer]

as long as you don't go to deep it's a step that won't hurt your goal to more consistent ammo !

21st Century makes the coolest flash hole reamers... Especially for small primer flash holes which can be undersized from some mfg. (May not be an issue for hunting rounds...) You can just tickle the hole to take off the high spots. Opening those up to std hole dia. typically worsens groups, so you need to be using the smaller diameter pin for decapping. That's why I always de-cap small primers with a Redding decap die; I pull the pins on my forming dies, or replace them.

I think 21st Century and Redding both make a deburring tool that indexes on the webbing of the cartridge head. This style cutter makes it impossible to cut to deep. The older style tools index on the mouth of the case and the slightest variation in trim length can either cause the cutter to chamfer the flash hole or fail to deburr.

 

[Savage 12BVSS]

I think 21st Century and Redding both make a deburring tool that indexes on the webbing of the cartridge head. This style cutter makes it impossible to cut to deep. The older style tools index on the mouth of the case and the slightest variation in trim length can either cause the cutter to chamfer the flash hole or fail to deburr.

I agree, however I only deburr once and that is always when brass is new and always already cut to trim length, gotta do this before weight sorting which I also do with new brass. I guess for fired brass that would make a difference what it indexes on but it never effected things the way I do them, I like them new and clean inside so I can see.

 

[birdiemc]

I cant believe with all the new teslong borescopes floating around, nobody is able to get some pictures of what finish other mfr tools leave behind...

 

[mountainman56]

Finally got around to taking some pictures. First two are Winchester brass, before and after using a Lyman flash hole uniformer. 3rd picture is untouched Nosler brass. I think I'm liking the results with your uniformer better.

 

[nvschütze]

I also uniform the flash hole because I believe the chamfer allows the primer flash to spread-out in a cone and start the combustion at the bottom of the powder column, as opposed to having a spire of flame shoot upwards through the powder column and ignite the whole mess of propellant at once. A slow ignition builds a consistent pressure. A dagger of flame up through the powder causes high pressures and inconsistent bullet velocities. At least that's what I believe...