Flash holes for pistol ammo

[Clint007]

Whilst admiring some processed mixed head stamp 45 brass I received, I noticed quite a bit of variation in size and shape. Some holes were even not fully round with tangents of brass blocking the hole.

Precision rifle outcomes aside, would these variations in the flash hole have any real practical impact on velocity variations, etc., for standard loadings?

C

[Clint007]

I found some discussions on a few forums most of which said it does not matter even for rifle for the most part, but especially not for pistol.  I think some of these partially wedged flash holes may be from the processing…this brass was deprimed, SS pin cleaned, resized and roll resized also.

C

[M1A4ME]

I've never done anything to flash holes except look at them to make sure they aren't plugged with cleaning media.

[Wobbly]

> The flash hole is one of the last features added to the case, and so it has to be punched. This punching operation is fairly rough, and so it leaves a LOT of variation in the results. The "tangents of brass" you see are the metallurgical equivalent of "hanging chad" that you sometimes get with paper. Holes can also be off-center, undersized and/or  oval.

All this is why tools like the RCBS Case Prep Center come with drill bits, chamfering tools and other cutters.

> If you are shooting in a competition category where details matter (like Palma Matches, 1000 yard rifle, bench rest, etc) then you should probably be looking at and standardizing this hole. So if your reloading processes includes spinning the cartridge in a lathe to do work on the neck or your resizing operation includes bushing sizing, then probably 'Yes'. Anytime you need ammo that is "double darn sure" to perform.

I take the time to do it on my carry ammo that I use for hiking. Truth be told, I've never had to fire at wild animals, but several times I have had to draw my handgun and backtrack. I simply want "to be sure".

[Clint007]

Thank you. The guy that processes the brass has a spring loaded hold down die that braces against the inside bottom of the case, and I think might flatten out some of these “hanging chad” edges down partially across the flash hole. This is all going to be practice ammo so I don’t sweat it.

C

[tdogg]

Yes, flash holes matter .  I've spent plenty of time uniforming precision rifle case flash holes. 

I too had the same concern shortly after loading for the first time on my S1050.  Dillon dies use a foot to hold down the case during the expansion/swaging operation.  That foot will flatten the flash hole extra burr that is left from its creation.  I noticed that some will even block the flash hole as you have also noticed. 

I actually drilled out the Dillon expansion die foot with a drill bit (can't remember what size I went with) to help minimize the contact with the flash hole burr material during swaging.  At some point I added the FW Arms dynamic hold down die and it has the same type of foot but I haven't done anything with it with no known adverse effects with my ammunition.  I haven't had a failure to fire that wasn't attributed to a light strike (Servicios y Adverturas primers are hard!!).

After it gets flattened by the foot, assuming the cartridge fires, it will get reopened by the decapping pin during the next loading cycle.  So I guess it is a self correcting problem if you load the case more than once.

Cheers,
Toby

[Clint007]

thank you for your thoughts that’s interesting

This brass guy deprimes, Then stainless steel pin cleans, and then Actually, resizes, roll sizes, and then polishes the brass. I filtered through quite a few, and only found one that had what I would consider a substantial obstruction of the flash hole by a flattened burr , It was about 50% of the surface area of the hole.

I’ll diplomatically ask him about this but I don’t really care; I do actually carefully select And inspect all the brass I use for high value sanctioned matches, these are just going to be practice rounds…

[Wobbly]

Note also that for about the last 10 years there have been experiments with various types of mercury-free and/or lead-free primers and some of this brass used 0.030" flash holes. Federal Syntech is one of these experiments. Also lots of complaints about Norma brand brass for having under-sized flash holes. They are probably punching 1.5mm, which equates to 0.059".

The typical American decapping pin is 0.060" and so most American made brass uses an 0.062" hole. (The RCBS case prep tool uses a 1/16" drill bit (0.062") to clear and standardize flash holes.)