primer pocket uniformer

[solocam72]

Any of you guys use one of these? I have one and have used it for several years, I use it on new brass and its amazing how much it removes from some cases and not hardly any on others, guess it goes to show how inconsistent new brass is. I have found weatherby brass to be one of the worst, at least my .257 weatherby anyway. The problem with mine is it gets darn hard on the fingers using it very much, I don't know the name of mine? Its a carbide cutter with a blue knurled end, was fairly expensive to the best of my memory. Anyway would like to hear your guys take on this tool

[solocam72]

Sorry for this, I just found another thread on this that I missed

[Unclenick]

I'll post a couple of points here anyway.

IIRC, the only spec drawings for primer pockets I've seen (old Olin and Remington military drawings) give the depth as ±0.001". It can take some time to scrape that off with a hand tool, though. It's much easier to chuck one in an electric screwdriver and let the machine do the work. You can make the cutting a little faster if you apply cutting oil, but then you have to wash and degrease the cases afterward.

A number of folks use the same tool (dry) to clean primer pocket residue out. With repeated firing the brass at the bottom of the primer pocket gradually flows rearward, making the pocket more shallow again. The higher the load pressure, the faster this happens. Using the tool for cleaning keeps the depth constant, though the brass is gradually getting thinner.

The main advantage to uniforming primer pockets is so seating primers to the same height below flush with the case head achieves the same amount of bridge set. This is mainly helpful with a priming system that fixes that depth, such as the one on the Co-ax press. The Sinclair priming tool can also be set to force a chosen fixed depth below flush when closed all the way. 0.004" to 0.005" are typical numbers. Under that circumstance it improves regularity of ignition. It is also good to maximize that depth for gas operated military rifle firing mechanisms that have floating firing pins, in that doing so helps minimize the chances of a slam fire.

That said, if you go to that trouble and don't also deburr your primer pockets, you are likely wasting your time. If you prime by feel, but don't also uniform the primer pocket profiles to keep primer seating force constant, you probably won't get uniform bridge set and are wasting your time. If you don't load for floating firing pin self-loaders, but do have the patience to use the K&E Primer/Gauge tool, then that compensates for different primer pocket depths, making the depth uniforming unnecessary for consistent bridge set.

[solocam72]

Thanks unclenick, that was a good read!

[Bart B.]

Here's my only test of primer pocket depth change with max loads that was expected to make them shallower.

The same Federal brass .308 Win. case was primed with Fed. 210 primers, loaded with 42 grains of IMR4895 under Sierra 165-gr. SBT bullets. 47 times that max load was fired with the same case, full length sized each time between firings. No primer pocket depth was measured between shots but all primers seated consistantly about .003" below case head with a Lee priming tool. If there was a depth difference, it wasn't enough to make any difference.

I've never prepped primer pockets in any way except to try all the popular tools and techniques testing them only to find out it made no difference at all in my .308 Win. and 30 caliber magnum match rifles. My reloads shot as accurate as the best of anyone elses; 1/4 moa at 200, 1/3 moa at 300, 1/2 moa at 600 and 3/4 moa at 1000.

But if it makes one feel better about their reloads, then by all means. . . . prep your primer pockets to the nth degree.

[hounddawg]

might just be mental but I have noticed a improvement in my LR groups since I started cleaning my primer pockets. Not that I am all that great since still can't break 1 MOA at 800 consistently. My best was last week with a 193

[solocam72]

Bart B., Do you do anything at all to your primer pockets, use a brush?

[Unclenick]

solocam72,

Primer pocket depth uniforming is really a benchrest loading technique, and like a number of such techniques, the difference it makes to accuracy is often buried in the noise of a shooting platform not capable of near bughole precision. Whether or not your platform sees an improvement in ignition consistency from it or not can likely be detected by chronograph, even if it doesn't show up in group size at short ranges.

To test that, fire the same load from two sets of cases, identical except one having primer pocket depth uniforming and the other not. I would run 15 of each, filling two 20 round boxes with 15 rounds plus 5 foulers. I would load the two sets of cases in the same bench session, alternating between cases with and without pocket depth uniformity. This is to tend to equalize the influence of any change in conditions that occurs during loading. When I fired the loads, I would run all ten fouling shots first. For the chronograph record I would fire rounds alternating between the two boxes also to share changing conditions equally. I would fire them at a controlled rate, record the individual velocities manually in separate columns to keep them straight, then calculate their velocity averages and SD's later.

If the velocity averages for the two sets of loads are not significantly different (look up statistical T testing for how to make that determination), and if the uniformed cases exhibit no better SD than the non-uniformed ones, you probably are not affecting ignition or ignition consistency in your weapon system with this technique. It would suggest other factors are swamping out the influence of primer pocket uniforming, and that until you eliminate them, no significant benefit is going to accrue to you from the practice.

IME, obliquely dovetailing what Bart reported, is that benchrest case prep steps are inconsistently useful in less exotic guns. I have an older single receiver lug M1A which would max out precision at about 0.7 moa. Trying Accurate 2520 one year, I could not tune loads to group below 1.2 moa until I started deburring the case flash holes. Then it settled to 0.7 moa. However, the stick powders I ran in that same gun would tune to 0.7 moa without deburring flash holes, and deburring the flash hole did not improve their performance further. They just lit up more easily, I suppose, but it's an example of a benchrest loading technique that mattered under one set of circumstances and not others. The bottom line is to do what Bart did, and test the methods on your platform, with your component choices to see what matters.


Bart,

Interesting to hear about your experiment. A couple more pieces of information would be also interesting to have. What sort of primer pocket depth uniformity did those Federal cases start with? Also, do you have the barrel length and MV average and COL you used? The reason I ask is I tried to estimate the peak pressure you'd have had with 42 grains of IMR 4895 by a couple of different strategies and came up about 20% below SAAMI maximum average pressure both ways. But that's without information on your gun or chamber, so it assumes velocity and pressure test barrel conditions with a standard chamber configuration. The other numbers would narrow the estimate some.

There was a sectioned case photo up on the board not too long ago of a primer pocket floor pushed back by pressure, but I don't recall the chambering. All I do recall is that I had expected to see the middle of the web around the flash hole dome back, as I'd found in some Portuguese surplus .308 brass I'd reloaded once (very hot initial firing as surplus ammo), but this fellow had flow from around the pocket that appeared to cause the bottom corners of the pocket to increase their radius (flowing in from the head). So depth at the center of his primer pockets might not have measured much differently, yet a primer anvil's feet might find bottom early.

[Jimro]

Primer pocket uniforming is a waste of time for most hand loaders. The theory that carbon residue in the primer pocket is a big source of barrel wear has been bounced around here a couple times, so there might be something to cleaning the primer pocket.

However I know of no one who has shown a measurable difference in accuracy with anything but benchrest rigs.

Jimro

[browninghunter86]

When I get my bullets and powder in I will try to test to see if my # got better or stayed same from uniforming the pockets. I know my group size shrunk a good bit but as you know that doesn't always mean it is the best

[solocam72]

I've been doing it long enough now that its just another part of my routine, I hate breaking routine so I suppose I will continue doing it, sure makes em look pretty if nothing else

[jepp2]

I'm not trying to suggest that other do what I do.

I have always cleaned primer pockets. Just prefer to seat new primers in a clean pocket.

I first started uniforming primer pockets on my rifle brass for the rifles with the best accuracy potential I have. Mostly in the goal of improving the consistency (along with reducing neck and bullet runout, sorting cases by weight, etc.).

When I saw how inconsistent they were, I started uniforming all my rifle brass primer pockets. I really like how uniform the priming seating is on the pockets that have been uniformed.

Then on my revolver brass, was encountering some primers that would slightly crack on rounds fired in revolvers with a very heavy firing pin strike. These primers were properly seated, but I didn't want to have to replace the firing pin. So I uniformed them and used CCI primers. I haven't had another split upon firing since then. How can you argue with this kind of result?

[solocam72]

What kind of tool do you use jepp2? I use a little hand turn tool with a blue knurled end, pretty sure its a carbide cutter, I bought it from a gunshop in Wa I did LOTS of business with when I lived there, the owner use to shoot a lot of small bore benchrest stuff and he advised me of the tool, it was kinda spendy for a simple looking little tool, iirc I paid 30 or 40 dollars for it? I use it now days to clean my pockets after each shot, starting out I only did it one time to new brass, it makes them look the same as what you have pictured. All I can say is it hasn't hurt anything and its part of my routine, my only complaint is its hard on the fingers if you sit down to a bunch of new brass! I figured they must make something like mine that would chuck up in a drill and definately be easier on the fingers

[jepp2]

What kind of tool do you use jepp2?

I started using the Holland's Primer Pocket Uniformer link. It does small rifle, small pistol and large rifle. It is a carbide cutter. On the small rifle/pistol side, it didn't get dull until I had done over 5,000. It is a carbide cutter, even though it doesn't list that on the site link I provided. The depth is not adjustable, so you can't mess it up (unless you use the large rifle in large pistol primers)

If I had to do them by hand (I did try) I wouldn't do them. I take the cutter out and chuck it up in my 18 volt drill and keep the speed below 800 RPM. It cuts really well with very little effort. No sore hands.

I'm using a Sinclair cutter right now, and I'm not sure I will ever dull it.

[solocam72]

Looks like a new tool I MUST have!

[reloader28]

I always clean the primer pockets just because.
I bought an RCBS primer pocket uniformer and have used it. It does a good job.I do think it is unnessisary for most reloaders, tho I have noticed a difference in accuracy. Plus one on Uncle Nicks drill idea. Thats the only way to go.

If you want a bigger difference in accuracy, I think the neck uniformer is a better way to go. I think you get a bigger gain. Its amazing how much difference there is in brands and the neck uniformity.

[solocam72]

Neck turning is something I've never done, I've looked at tools for it many times but just never followed through with it. I know an ole boy that swore by it, id bet he owns every reloading tool known to man, his loading room is bigger than my living room and its stacked from floor to ceiling, he's 65 yrs old and never been married, owns more guns than most large sporting goods stores, he just recently purchased a kriegohff double rifle in .600 nitro express, said he got a great deal on it at 15,000.00

[solocam72]

Maybe that kriegohff was a .470 nitro express? Either way it was a bargain to him

[browninghunter86]

uniforming tool in drill takes the pain out of your hands!! I believe it is more consistent than doing it by hand too?

I use the K&M tool since I only do it on my 308 match brass.
https://www.kmshooting.com/catalog/p...tion-tool.html

[reynolds357]

I have one, but it really amazes me that your .257 WBY does not have uniform primer pockets. Norma brass is top end. Winchester brass is what I have problems with.

[Romeo 33 Delta]

I have an RCBS prep center and use that for uniforming my primer pockets with the RCBS hand uniformer tool heads.. It may not make a bit of difference, but I feel it makes seating primers easier as well as more consistant. I also chamfer/deburr the pocket at the same station. I've found that with some calibers that getting a perfect shellholder match for priming (Lee Hand Primer Tool) isn't possible and if just a hair off center, without a chamfered pocket, things get "sticky" because things are just a hair off. The chamfer helps to allow the primer to better position so she heads for the pocket like it's home!

With my set up, I will have a batch of brass in the tumbler, running while I de-prime & resize the next batch. If I use a collet neck sizer, I clean my pockets (with a uniformer which works really well) and then after emptying the tumbler, throw the new batch in. If I used a F/L die and Imperial, I get those into the tumbler first and then clean the pockets after ... just easier to handle "dry" cases.

I do this after each shooting session, after cleaning my firearms. The brass gets put back in their respective boxes and set aside for reloading come Winter. Speaking of which, it should be here any day and I'm all ready to go! Bring it on!

[old roper]

Little bit of history on the one I use it's from Varmint Al's page. Dick Wright started making his for the Br guy's.

"PRIMER POCKET.... I use the Whitetail Design's carbide primer pocket tool. The tool is expensive, but will last a lifetime if you don't drop it and break it. On new brass, this tool will cut the primer pocket to the correct depth and remove the fillet radius at the base of the pocket. This cutting process only needs to be done once to new cases. For each reloading, the primer pocket can quickly be cleaned with the same tool. If your loads are hot, you will be able to cut metal at the base of the primer pocket after each firing. This is an indication that you are yielding the brass case head and setting back the base of the primer pocket slightly. When you clean the primer pocket this way, you will get a better "feel" when seating the primers (no variable fillet at the base of the primer pocket), and you will not be shooting extra primer residue down your nice shiny barrel. Note: Dick Wright, the former "Mr. Whitetail", who made my Whitetail Design's carbide primer pocket tools, has gone out of business but designated Russ Haydon's Shooters' Supply as his successor for the primer pocket uniformer tools. They sell his original knurled handle style as well as the same cutters (Large Rifle, Small Rifle or Lapua) alone or in the screwdriver handle, which is the Haydon-style."

http://www.shooters-supply.com/photo...tUniformer.jpg

http://www.shooters-supply.com/reloading_equipment.html

I always feel some things are just mental game and this may be one.

[solocam72]

Old roper, I use the whitetail also, I didn't know the name of it til I looked at the links you provided, there is a good picture of it in the second link, I have owned and used mine for several years now, it does a really good job but sure gets sore on my fingers if I sit down to a batch of 20 brand new brass, I've done hundreds and hundreds of rifle brass with it over the years but not at one sitting!

[solocam72]

Reynolds357, I have some old .300 weatherby brass and it is a real pleasure to work with, very little to any material to remove from the primer pockets, this brand new .257 and .270 weatherby brass are identical, I bought 2 boxes of each to dissasemble for the brass to reload what I wanted, both the .257 and .270 have been some of the worst I have ever worked with, I question the quality of this new stuff compared to the older weatherby brass?

[Bart B.]

Solocam72, I've used wood toothpicks, bristle brush primer pocket cleaners, flat tip screwdrivers, primer pocket uniformers, a toothbrush and several other now forgotten things to clean primer pockets. I've also uiformed their flash holes to exact .045" diameter with a drill, chamfered their flash hole inside with a tapered uniformer. Nothing seemed to make any difference in the .308 Win. match rifle used to test the methods; 1/2 MOA at 600 yards for all of them. Including uncleaned, yes residue coverd primer pockets that were not surgically clean after tumbling in walnut and rice media.

Unclenick, that 42/4895/165 load that went 47 times in the same same as the standard M118 7.62 NATO match load with a slightly heavier and fatter bullet. Of course, the primer and powder lot was different. But it was fired in a SAAMI spec chamber with a .2990" bore and .3077" groove diameter 1:11 twist 26 inch barrel. Muzzle velocity (chrono'd at 15 feet) was around 2610 fps with around 2500 rounds through that barrel. So my SWAG is it was about 50,000 cup for peak pressure as that barrel's specs for diameters are smaller than SAAMI as well as MIL SPEC ones. An M118 round shot its 172-gr. bullet out at 2650+ fps from that barrel as I remember.