Perfect Union banner
1 - 17 of 17 Posts

·
Registered
Joined
·
3,331 Posts
Discussion Starter · #1 ·
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 ??

kwg
 

·
Registered
Joined
·
986 Posts
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
 

·
Registered
Joined
·
3,331 Posts
Discussion Starter · #4 ·
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
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.

I did try some larger primer holes and the results were not good. Too many flyers and several seperated cases. Since I don't have a chrono I can't give you any information about pressure. I can only tell you going bigger than. 082" was counter productive and created more seperated brass.

In a bolt action my best groups were with the consistently sized .082" hole. When time and resources allow I plan on doing some more shooting. But, I think making the primer hole size consistent has been worth it. I use my drill press to run the drill. I mount the drill bit and simply push the brass up to the bit. I do not chamfer the inside of the brass.
 

·
Registered
Joined
·
8,470 Posts
yeah I've done that, deburred the inner flash hole and used the RCBS center drill tip bit.
both my '06 loads and x39 loads I made up for tests on paper - which lead to selection for a white tail load. settled on the Speer FBSP 150 gr .308 bullet.
basically 30-30 power level.
 

·
Registered
Joined
·
986 Posts
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.
 

·
Registered
Joined
·
3,331 Posts
Discussion Starter · #7 ·
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.
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.

I did test some with larger holes than .082" and I found little change in visible pressure signs. I did have some near brass separations with the larger the holes. I needed a bore scope to find those inside of the brass. But, I don't have a chrono and that would be the real test for pressure issue based on velocity.

It was an interesting test and some may consider it a waste of time but like the TV comedy says "I gots to know". Now I know. Here is a study on the issue. My findings and the writers findings don't match. But, I did not have his support team and budget he did. kwg
The effects of physical flash hole deviations on factory-grade rifle ammunition (mst.edu)
 

·
Registered
Joined
·
986 Posts
interesting that the cases are ejecting more consistently. But it makes sense, by uniforming the flash hole it would give a more constant recoil force on the bolt affecting bolt rearward velocity and unlocking the bolt for it's rearward journey. I can't see how that could not help accuracy, especially in a mini. In my mind if the brass is ejecting in a more uniform pattern it would mean that the bolt rearward velocity is more consistent, due to the nature of the ejector/bolt system. That would lead to a more uniform feeding/seating into the chamber of the next round. Kind of falls on the heals of the infamous first round flier in the mini and some other semi-autos and letting the slide rack home instead of gently feeding the first round. The mini especially has a loosie-goosie chamber, a hybrid, not a 223 or a 5.56, more like a wylde but with a longer throat. I think that could be said for the mini 30 also, Ruger has their own reamers for that caliber. Not sure about the 6.8 SPC, but they missed the boat on that one too, with the 6.8 SPC spec 2 chambers coming later. But that was a Remington goof-up. Thanks for the opening post, solving the accuracy puzzle one piece at a time. It would be interesting to check some match quality brass to see if the flash hole's are more uniform.
you might have seen this, but if not worth the read, tips from the Army Marksmanship team.
Reloading 101: Primer Pocket and Flash-Hole Conditioning
 

·
Registered
Joined
·
605 Posts
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.
Bepe

Light Auto part Fashion accessory Electronics accessory Automotive wheel system

Writing implement Office supplies Font Stationery Plastic
 

·
Registered
Joined
·
3,331 Posts
Discussion Starter · #10 ·
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.
Bepe

View attachment 65519
View attachment 65517
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.

Just for my own information I actually took some holes to .101". I gained no accuracy benefits and upon inspection of the brass there were signs of excess pressure and several pieces of brass were showing sign of separating. I used my bore scope camera to see the near separations. Obviously, I suggest NOT to do this and if you do it would be at the risk of getting some unwanted results.

I used the #45 drill bit to get .082" diameter holes. The #46 gives a .081" hole but only cleans up about 50% of the primer holes. The #45 cleaned probably 90% of the holes. That other 10% was slightly larger than the .082". Any brass I took larger than .082 I discarded into my brass bucket just in case there was any brass that was damaged during my tests.

Another issue is the quality of the brass. It's my understanding that the Lake City brass is punched verses being drilled brass in the more expensive makers. There is no doubt the Federal 5.56 brass I have is punched based on the number of burs inside of the case. I would say the holes are punched by the lowest bidder with the dullest tools.

Even if I don't get better accuracy out of my Mini, I'm willing to uniform the primer holes in the brass if I can get brass that pretty much lands in one spot. That is the advantage of winters in Iowa, I have time to mess with this over the winter and shoot the other 3 seasons.

kwg
 

·
Registered
Joined
·
605 Posts
Pic #1 is the flash hole deburring tool. A kit of different caliber guides is supplied with the kit. After sizing and trimming I run the guide into the case neck. Push the cutter rod until you feel contact with the case head. Give a twist and the spiral cutter will remove the burr. You can feel it cutting. Once cut there will be no more resistance on the cutter when turning. Simple process. It does not enlarge the flash hole...just chamfers the burr.

Pic #2 shows the primer pocket uniformer. It has a depth specific shoulder on it. Select the proper cutter for the primer size. Insert into case and twist. It will cut the bottom of the primer pocket and stop when the shoulder hits the case bottom. Can't go any deeper as the shoulder makes contact. I've never found it to take an excessive amount of material off but it will cut some. Primer pockets look like the pic in Walkenbears link. This insures all the primers are the same depth.

One time deal for both operations. I usually do it on the initial brass prep of new brass. Accuracy is all about consistency and uniformity. If a little extra work produces such.....than I'm in. I enjoy the task and the hobby. Nothing better than shooting a one hole group with your reloads.

Bepe
 

·
Registered
Joined
·
605 Posts
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 ??

kwg

In 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.
Bepe
 

·
Registered
Joined
·
8,470 Posts
different makes of brass cases likely varying metal composition, thereby varying neck tension of the seated bullet.
I don't shoot formal matches but do my own bench rest group size tests with among others my Mini30.
different make cases have an effect.
 

·
Registered
Joined
·
3,331 Posts
Discussion Starter · #14 ·
In 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.
Bepe
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 in
size. It was the differences in hole size that got me going down this rat hole.

Prior to shooting to test for accuracy I measure the lenght of the brass and I trim brass as needed to get consistent length. The only thing I don't do is weigh the brass. I would like to have a Labradar chronograph to check the speed but I have other demands for the money.
kwg
 

·
Major General Chit Chat
Joined
·
1,632 Posts
I 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.
 

·
Registered
Joined
·
3,331 Posts
Discussion Starter · #16 ·
I 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.
Hello Beck
I picked up some once fired PMC today from a young man who did not reload. I have used PMC brass before and it is good brass. I will check hole size when I resize it to see how consistent it is. I have bought "once fired" brass from the internet and you are taking a chance. Sometimes you can tell by looking at the brass if it has been fired more than once and sometimes you can't. I like military brass that has the crimped primers. If the crimp is intact you know it's only once fired. Shooting new brass used to be economical but not lately. Anytime new ammo is $1 a round or close to it, that takes the fun out of shooting new ammo. I'm not independently wealthy enough to shoot new brass at every range trip.
kwg
 

·
Major General Chit Chat
Joined
·
1,632 Posts
I hear ya, KWG. I can't afford much these days with prices as they are. I got most of my x39 brass before covid-19 became a thing, and the brass I bought after covid hit was at pre-covid prices from honest, reputable people. Now I have have enough to last for many years to come.

If I was short on brass I don't have anything against once-fired per se, but it depends on the source. I know there's a lot of 1FX brass out there because there are so many people who aren't into reloading. I should clarify that I would buy 1FX brass if I know the person selling it.

Handloading/reloading is a fairly new activity for me. I left a lot of good 1FX brass lying in the dirt in the early days when I first bought my Mini-30. After a few years I started picking it up for one day when I might try my hand at reloading.

And yeah, PMC brass looks good to me. I only have 20 1FX pieces from an older box of PMC soft point I finished off within the last year. I'll load it back up with something at some point.
 
1 - 17 of 17 Posts
Top