That is a lot of work. I'm making the holes in my brass uniform by running the #45 drill bit through the holes. This hole size is .082". This is the biggest hole as recommended by SAAMI. I did shoot some of these out of my Mini. I did not see improved accuracy but I did see brass land in almost the same place verses being spread across the hole range.Personally I haven't, but I did know someone who did and his loads were very accurate, even out of a mini-14. saw him shoot about a 1 1/2" 20 round group (rapid fire) at 112 yards from a old standard mini that gundoc worked on. In addition to uniforming the primer pocket he deburred the inside of the flash hole. Also would sort his brass by weight and check the concentrically of the case mouth and runout of the bullet using a Sinclair Concentrically Guage.
not for me, just yet
For .223 I have settled on the .082" hole. That is the max hole diameter as per SAAMI. It seems that even with Lake City the holes vary in size. I can't say that doing this with the Mini 14 has improved accuracy (at least yet I can't say it) but my brass seemed to land in one spot instead of all over the place. I would say that 90% of the brass I ran through with the .082" bit I have changed the hole diameter by at least a small amount but the other 10% I have not changed it at all. In other words, the hole is slightly larger than .082". With that in mind I also reduced the load by a small percentage just to make sure there is no over pressure.the same person, rdhunter (PU name), a vietnam vet and one of the first of the Army Rangers also told me a story about one of the dirty tricks they used which was to leave ammo that was modified for the VC to find with enlarged flash holes that would cause the firearm to blow up when the excess gas came rushing out of the flash hole into the primer pocket. So yeah stick with the SAAMI specs on max size. Interesting in the variations you mentioned just in modifying the flash hole. But in the end reapeatable accuracy comes down to all things being consistant, so uniformig the size of the flash hole would be a step in the right direction.
Just my observation on predominately on Lake City brass and that is once I uniformed the hole to .082 there were no additional burs inside of the brass at the flash hole. The walls of the flash hole were straight and there was NO chamfer on the inside of the brass at the flash hole but there were no to very few burs in the ones I looked at with the bore scope. With other brass there were lots of burs. Federal 5.56 was bur city after making the home uniform to .082. I would of had to take the hole to .090 or larger to eliminate the burs. I tried some .090" holes and I did not get any additional accuracy plus I was starting to see some pressure signs.Been doing flash hole deburring and primer pocket uniforming to some degree for years. Enlarging or altering the flash hole itself.....never.
Usually I debur the flash hole on both pistol and rifle brass during my initial prep. Primer pocket uniforming is only done to rifle brass. As per Walkenbears link above..... the quality of the rifle brass determines what I do. I have found that most of the American brand brass needs attention. Usually the flash hole is the big culprit. Heavy burrs that will leave you with a pile of shavings after servicing a batch. The better quality brass like Lapua or Norma rarely needs any modification. Flash holes on the better brass are usually clean as a whistle.
Have I noticed any improvement in accuracy. I don't know. Never done a comprehensive test. I can say that when I was shooting CPM matches my brass from the 20" Colt would land in a circle the size of your hat. Accuracy was always as good as the shooter. All depends on the firearm I'm shooting the loads from also. Not going crazy if the gun is not capable.
Sinclair International has the equipment if you are interested.
View attachment 65519
View attachment 65517
I was recently noticing that much of the brass I collect from the range has a huge amount of variations in the primer holes. All the way from .076 to .082 thousands. (these are the SAAMI standards) Has anyone else played with primer hole uniforming ??
Yes, I use range brass. But, when I shoot for accuracy I try to get the same brass for the "test". For poking holes in paper I'm not as picky. Only brass like Hornady and the more expensive brass have holes that are constantly the same size. Lake city has holes from .076 to .082 inIn rereading the OP, regarding the variation in flash hole sizes, we may have found the smoking gun!!! ...... "range pickup brass"...... I pretty much overlooked that fact the first read. If you are using many different brands of brass it can only be expected to have variance. Not only in the flash hole size but case capacity....brass thickness and probably a few more parameters. The number of firings the brass has been through may also make a difference.
Curious if you have found any FH size difference in brass of the same manufacture?
Accuracy is all about uniformity and consistency. Neither can be achieved with different brands of brass. Not condemning anyone for using range brass., you have to do what you have to do........just not the optimum.
Hello BeckI use a primer pocket uniformer/cleaner, but I've never uniformed flash holes to a standard size. This thread has me thinking about it though. I avoid range brass except for my own. Sometime ago before Covid prices kicked in I bought some 1FX Geco 7.62x39 brass from that seller on Gunbroker that's been selling it for quite a long time. I got it so cheap I wonder if the seller gives you what you pay for. Mine was in pretty bad shape, so I won't do that again.
Most of the x39 brass I have on hand is brand new. I have a lot of brands and I don't mix them when loading. For example if I work up a good load using Lapua brass, I'll start over if using the same projectile with IMI brass, or Starline, etc.
The thickest brass I have is from my 1FX Federal American Eagle. The thinnest to my eye is Winchester. The case capacities vary from brand to brand. Not much variation but it is measurable.