SmallCaliberCentral

Oops! Somewhere I thought I had read that the .204 Ruger was another user of the small flash hole however I have since found that my 5/64” drill bit (~.078”) will easily pass through new Hornady brass.

Sinclair has their .081 Flash Hole Reamer #07-3081 for the .204 and most others with the exceptions being the few Lapua cases listed on their site as needing the .0625 reamer. This reamer looks to index from the outside bottom of the primer cup and will center and enlarge the flash hole to .081” but without shape (chamfer) on either end.

Sinclair’s flash hole deburr tool #05-1720 with pilot #26-204 that works off the case mouth does fine IF all you want is to deburr previously fired and not resized cases (collar fits) and are not too concerned about a consistent chamfer shape that can only result if cases are always first trimmed to a set length before use of the tool. Their Generation II tool does it “right” but the shaft is too large to fit through a case neck of less than .22 caliber.

K&M has the Model #UM20STD Flash Hole Uniformer, Master Cal .19 & .20 with a silly looking wire nut handle. They also have the much better lookin #UPSTD Flash Hole Uniformer, Professional – Standard 0.080 with a hex drive end and collar to aid centering but I’m guessing that as with the Gen II Sinclair the shaft is too large to pass through the neck of anything less than .22 caliber, thus the existence of UM20STD.

I wish I had held out for the K&M or some other deburr/chamfer tool that indexed off the bottom inside of the case instead of the mouth but the piloted Sinclair tool was already mine before I was enlightened by a search of this forum.

Will someone please confirm that the UM20STD is a must for use of the K&M tool in .204 Ruger, and that the silly lookin but multi-purposeful wire nut is hiding from view the threads that will perfectly fit one of my three existing Redding handles?

I GUESS THE FLASH HOLE DEBURRING TOOLS ARE OK,IF YOU TRIM ALL THE BRASS TO A UNIFORM LENGTH ,BEFORE DEBURRING THE FLASH HOLE.THE K&M IS SIMPLE AND CHEAP.I GOT ONE FOR 20CAL,REMOVED THE ,sic,WIRE NUT,AND CHUCKED IT IN MY 3/8" DEWALT CORDLESS DRILL,WHICH I LOCK IN MY BENCH VICE.WEARING A GLOVE,LEATHER,OR LATEX,I ACTIVATE THE TRIGGER WITH THE THUMB OF MY LEFT HAND WHILE RUNNING THE CASE ON THE TOOL WITH MY GLOVED RIGHT HAND.WORKS SLICK.BTW,THE TREADS UNDER THE "WIRE NUT",ARE OF A WOOD SCREW TYPE,NOT MACHINED TO FIT IN A REDDIND HANDLE(MY GUESS).

Thanks Joe – I have hickory with nutin better to do and several drill motors to choose from. I take it that the “Professional” model is too large in dia. to pass through the .204 necks.

Is the shaft on the “Master Cal .19 & .20” enough to reach bottom with 243 Win. which is presently the longest case I load? If it’s too short I’ll have to force myself to buy both.

Never mind. I just placed an order for both. What’s next – 3 angles on both ends – swirl port – this junk is getting crazier than racing…?

The .204 Ruger uses the standard sized flash hole, .080" with decapping pins of .062" +/-. PPC cases use a .060" flash hole, and decapping pins .057" +/-. Where I ream PPC cases .0624" to prevent sticking an errant .060" pin, there is no need to ream .204 Ruger flash holes larger or more uniform.

Also, I use the .204 Sinclair flash hole deburring tool 05-1720 set to maximum depth and use feel to establish when the burrs are cleaned up.

There is nothing to be gained in trying to establish the same profile to every flash hole relief, given that any gain in ignition uniformity is theoretical and will not improve the normal variation in accuracy of the .204 ammunition/rifle system. The average varmint hunter and rifle is incapable of using the minuscule gain, if any, in the field. There is some discussion that even the practice of flash hole deburring does not produce statistically identifiable improvement in accuracy in these rifles.

I still use the flash hole tool to deburr, and then only enough to observe a small bright ring around the flash hole when viewed from the neck. The normal variation in case head thickness of production lots of brass make an exact repeatable contour impossible anyway, as most brass is impact extruded over a series of machines and dies then mixed together. This is busy work that I do when uniforming primer pocket depth, it is something of a ritual more than practical, but makes watching NFL or PGA matches more productive during commercial breaks.

My suggestion is to simply deburr and load.

Update: Sorry I was writing when you posted that you ordered the tools. Ignore my comments.

I already have the Sinclair toy for the pocket and their piloted deburr tool. The K&M toys should be here soon. If the Jewell replacing the factory X-Mark doesn’t make a noticeable difference I will be evil. But at this stage in my life I doubt that I will ever notice any gain from anything more than a properly seated primer and possibly gittin rid of a big flap left by the punch. It gives me something to do and those tiny narrow rings of freshly cut metal just make me feel good thus better shooting from the feel good alone.