Flash Hole Uniforming?

[GunAdmirer]

I've noticed that flash holes in some cases are all sorts of sizes and shapes. Anyone use a tool to uniform flash holes? I know you don't want to make them larger than a standard size because of increased pressure.

May not seem necessary but, hey, some deburr flash holes and uniform primer pockets.

Sinclair makes a tool for an exotic European cartridge but what about standard cartridges?

I haven't tried anything, I'm just wondering about it.

 

[Jim Watson]

I use a flash hole uniformer; it is amazing how much brass you can ream out of burrs around the holes. I even went back and did my Lapua .308s upon reading that it would help them with Ball process powders.

I do not use a primer pocket uniformer except on .38-55 BPCR target brass, but I am a pretty casual LR shooter.

 

[GunAdmirer]

Flash hole uniformer or deburring tool? Who makes/sells one for standard cartridges?

 

[ocabj]

The above is the newest version by Sinclair. I use the older model, myself.

 

[GunAdmirer]

That's a flash hole deburring tool - not uniforming.

 

[taliv]

i'm fairly certain sinclair makes both for large and small pistol/rifle primers. i wouldn't expect a different uniformer for each caliber.

 

[ocabj]

I'm not sure how you differentiate between a flash hole deburring tool and a flash hole uniforming tool. But, deburring a flash hole will uniform it.

 

[GunAdmirer]

Deburring the flash hole will make it the right size and more perfectly round?

 

[ocabj]

Yes. A flash hole deburring tool is a cutter. It's going to make the holes a uniform size.

As far as brass prep, the tools I use are the flash hole deburring tool, the standard neck deburring and chamfer tool, and a primer pocket uniformer.

 

[Khornet]

Primer pockets are UNIFORMED

and flash holes are DEBURRED. The above Sinclair tool (I too use the older version) will work for all standard, and many non-standard, cases. It removes the burr inside the casehead and reams the hole to uniform diameter and roundness, although it can't correct an off-center hole.

The idea is to make the primer blast uniform in power and shape, and narrow holes will decrease flame power and burrs will alter its shape.

How critical is it? Dunno. I give all my brass for rifle the full treatment: flash hole, primer pocket, neck turn, sort by weight. Never tried doing just one of them. But the treatment does work. I even worked up a batch of 100 cases for my accurized M1 and saw a clear difference, even though I shouldn't matter with a semiauto military rifle. Then again, it has been accurized and has a match barrel.

 

[ocabj]

...although it can't correct an off-center hole.

Yes, this is a very good and important point.

 

[GooseGestapo]

MidwayUSA also sells two different tools.

One reams the flashholes and chamfers them both reaming and "uniforming" them.

The other tool is a Primer pocket reamer/uniformer.

The above mentioned flash hole reamer/uniformer is for a standard case. For cartridges such as the .22PPC/6mmPPC, and .22/6mmBR which use a 0.060" flashhole, will need a smaller diameter reamer/uniformer.

The only rifles where I've seen a benifit to "reworking" the flash-holes has been with some of the above mentioned bench-rest cartridges where it will take some "rough" brass from shooting in the "3's" to down perhaps in the low "2's" or high "teens".

Or, in other words, If you have a 1/2"moa rifle, you "might" see 0.15" improvement.
Or, you might not !!!
Such has been my case, However, I still do it as it won't "stretch" your groups either, if done properly.

 

[Shoney]

In order for the deburring tool to work uniformly, the cases must first be trimmed to the same length. So you must also have a case trimmer.

I have used the Lyman deburring/unforming tool for over 25 years on all my cases. Only one rifle showed any results, 6mmRem Custom target rifle (used for hunting). The results were minimal. I still deburr and uniform all my cases none the less (suppose I’m anal retentive ?????)

 

[Uncle Don]

I don't think that this by itself will make a huge difference, but when you combine it with proper trimming chamfering, primer pocket uniforming, neck sizing - it all adds up to a difference. In my experience, there has never been a magic bullet - just a combinantion of several things that many of us do.