BR/PPC Flash-Hole Deburring Tips
There have been some questions on our Forum regarding the recommended procedure for flash-hole uniforming on Lapua 220 Russian (PPC parent), PPC and 6BR cases. The factory spec on these cases is 1.5 mm (.059″) for the flash hole. In the past, we found it was normally not necessary to touch the flash holes on Lapua PPC/BR cases. However, with recent lots, a few cases per box will have a little sliver of brass that may obstruct part of the flash hole. It is advisable to remove this–but you don’t want to enlarge the rest of the flash hole in the process. There are a lot of tools on the market to do this job, but we’ve found that some will actually enlarge the flash hole to as much as .067″ which is not good.
The problem with the Lapua brass is a little “quarter-moon” of brass that forms on one side of the flash hole. The objective is to knock that out without increasing the diameter of the flash hole. A simple way to do this is to simply punch out the hole using a #53 or 19/32 pin drill bit in a Pin-Vise (below, about $5). The #53 bit measures .0595″ while a 19/32 is .059375″. You can find pin vises and bits at hobby stores or eHobbyTools.com.
Sinclair Int’l has two flash-hole tools, one that works from the outside (DB 07-3000) and one that works from the inside (DB-2000). The DB-2000 is spec’d to ream a .060″ hole. Depth of cut is set with a conical collar that indexes on the case mouth. Note, this tool can also cut a chamfer or funnel on the top edge of the flash hole. We recommend you set the depth stop so you only clean up the flash hole and do NOT cut a funnel. We also recommend you actually measure the cutter tip to ensure it is the correct diameter–some examples have been oversized–the same problem we found with other brands.
Both Forster and Redding supply dies with a .057.-058″ decapping pin for use with BR and PPC cases. However, the “normal” small decapping pin on some other dies is .0625 (1/16″). Sinclair makes a second tool, DB 07-3000, that cuts to this diameter (.0625″), going in from the bottom side.
Sinclair explains: “This tool was designed specifically to ream small flash holes (.060″) to exactly .0625″. It enlarges the holes just enough for the die maker’s decapping pins to go through without getting stuck… This 3-piece tool has a stainless steel guide that centers the reamer in the primer pocket from the outside.”
Which tool should you use? We prefer to keep the flash-hole as close to factory spec as possible. However, plenty of BR matches have been won with cases reamed to .0625″. The important thing is to remove whatever obstruction may exist in the brass, and make sure all the cases are uniform, whatever hole size you prefer.
I ordered the DB-2000 because it was advertised as .060, when i got it measured .065. I sent it back. I’m still looking for a deburring tool that wont enlarge the flashhole.
Ken Markel (K&M) mic’d me one before sending it…told him smaller than 0.0590″ it was, and does not touch the diameter of the flashhole.
Ed,
1. Thanks for heads up. Removed 19/32 reference!
2. eHobbytools.com has a 1.5mm pin vise bit. That matches the Lapua spec. YES it is definitely possible to push or pop out the flake with the right sized pin vise bit. Just push and spin quickly to remove obstructions without increasing the whole size.
3. You’re right, most of the tools on the market are spec’d to 1/16 (.0625) and we’ve seen them cut up to 5 thousandths larger.
1. Seems missed math check, 19/32 = 0.59375, not 0.059375.
2. I am trying to reach a supplier that has drill blanks (hopefully that means no cutting flutes) – http://www.buydrillbits.com/products/hss/gp2.php?c=DRILLBLANK#DB55 – they list both the #53 (0.0595) and the next smaller (#54 at 0.0550). Seems one of them might work if it is actually possible to “push” out the burr.
3. I contacted K&M by phone re their tool on 2/10/2010 – http://www.kmshooting.com/catalog/flash-hole-uniformer-tools/flash-hole-uniformer_professional-ppc_0062.html. Response – the pilot is spec’d at 0.062 BUT may be as large as 0.064 (in which case some material may be removed).
Incredible to me after almost three YEARS that an appropriate tool has yet to be developed. If there is one, please provide info.
Follow-up…
I am interested in finding a flash hole deburrer for 6.5×47 Lapua brass. I suspect that the new PALMA brass with small rifle primer pocket will have the same dimensions and issue. Anybody interested?