Home Forums Hunting & Shooting Ask The Gunwriters Shallow primer pockets

I have been reloading Seller & Bellot 7x57 cases and have noticed that reloaded cases cause the bolt to close hard. After I remove a loaded case from the chamber I see that the primer has obvious scrape or rub marks on them from the bolt head. Loading a case without a primer is a non-issue. The problem is not with the primers being too large as I have used them in numerous other cases without issue. My question is—am I in danger of having a round go off as I close the bolt on on a loaded case with these shallow primer pockets?

I cant say for sure about premature ignition with a high primer in a bolt gun, but it doesn't seem like an optimal condition. Situation normal with all the S&B rifle brass that I've seen lacking in diameter & depth. I've heard the same from others as well. You could possibly uniform the pockets deeper, but the tool doesn't change the diameter enough for easy seating in the 2 or 3 cases I've tried with an old Hart depth uniforming tool & also a Whitetail carbide tool. Maybe a primer pocket swage will help. Mine broke years ago & hasn't been replaced. I'm just not that desperate or interested in wasting more time or $$ on this brass. If your primers aren't tight going in, maybe a depth uniformer alone will work for you. If I remember correctly, I had to go .010-.015" deeper to reach flush or a touch of recess. The Hart tool is adjustable, the Whitetail tool is not. I wonder how thick the brass web will be after adjusting the pocket depth & if it will matter? It seems like decent enough brass, but is it really worth all the dicking around to be reloadable? Mine sits in the scrap brass bucket waiting to be recycled. YMMV

That's a damn dangerous situation....I saw what can happen first hand.

A guy two benches down from me was working with his 30-06 Model 70 hunting gun. He mentioned to me that he was having trouble closing the bolt on his reloads and asked if I'd take a look at it. I watched as he chambered a round and it looked like it was pretty snug when he closed the bolt. He started to open the bolt and BAM...it went off!

He was damn lucky the bolt had j-u-s-t started to rotate when it went off. If the lugs had cleared the lug abutments in the receiver, he would have caught the bolt right between the eyes.

After everything settled down, I took a look at his reloads. All of the primers were far enough above the case head that you easily catch them with your fingernail. With my dial caliper, I measured them at about .010 above the case head....a little hard to do but that was in the ball park. He said they had gone in fine, using the priming tool on his Rock Chucker.

I took a couple loaded rounds over my bench, pulled the bullets, dumped the powder and pushed the live primers out. I had some Federal 210's in my range box and pressed those in with my hand primer tool...felt fine. But they were still way above the case head. Pushed the Federals out and used my carbide large primer uniformer on the primer pockets until it quit cutting. In with the Federals again and now they were about .004 below the case head.

He threw all the brass, bought new Winchester 30-06 brass and went happily forward.

I suggest you uniform the pockets to the correct depth before firing another round. Be careful!

I have a lot of S&B brass for my 7.62x54r. I like it. It's good brass. In my experience, the biggest difference is the factory primers are installed flush with the case head, not slightly inset like most other brass. So, the reinstalled primer will expected to be flush, not inset. The pockets are tight, I really have to reef on the handle, but in a few reloadings they are tolerable. After pressing the primer home, I run my thumb over it. Any significant protrusion is easily felt and I will give it another press to make sure it's set properly.

The only brand brass that I've experienced shallow primer pockets was Sellior & Bellot in .308. I could definately feel the primers protruding with my finger tip. But the brass chambered fine and shot really good groups after fire forming.

This isn't really relevant to this specific instance, because it's so extreme.

But when the .17 Hornady Hornet first appeared, some of the Hornady ammo had VERY shallow primer pockets. If you seated standard SR primers, the case wouldn't even come close to chambering. This was back when the factory ammo (believe it or not) was almost as cheap as handloading--and bunch of prairie dog shooters bought cases of ammo, then sold the once-fired brass.

I bought somewhere around 300 pieces of such brass on the Campfire Classifieds, for a very good price. But when it showed up, it turned out to be the shallow-pocket brass. I solved the problem by sizing/depriming all the brass, then putting a primer-pocket reamer in a drill-motor and running it into every case, which didn't take all that long. They worked fine, and am still using the brass.

But what I've wondered ever since is where in hell Hornady got the "shallow" primers!

I've made primer pocket reaming part of my standard prep for new brass. I've been using more Norma and Nosler brass in the last few years and these brands seem to have issues when trying to seat primers deep enough. This may also be due to my use of Federal LR primers which are .0005 larger in diameter than other brands IIRC.

The Sinclair primer pocket reamer with adapter to use in a drill driver makes quick work of this task. My old RCBS reamer got too dull and would bind up my case prep machine when trying to ream pockets.

Had my first experience with shallow primer pockets this past summer. On my buddies 300 PRC, with his once fired Hornady Match brass, and as usual I cleaned up the primer pockets real good with a Hornady power case prep tool. Thought I reamed the pockets out good and still got slightly high primers. Those primers have been used in other stuff with no problem. Figured those primer pockets are a bit out of spec and planning on trying to get 'em a hair deeper next time with the power tool. No issues with function in the gun, they chamber & shoot real good.

Dunno about that statement concerning Federal primers.

I'd heard all sorts of things about primer dimensions over the years, and a few years ago decided to measure a bunch to see what was up. Could find NO consistent difference in large rifle and small rifle primers of various American brands--and in some instances different manufacturing lots of the same brand averaged smaller or larger in diameter.

Measured 11 brands/types of Federal, Remington and Winchester Large Rifle primers, with a digital Starrett micrometer, all that the same temperature. One lot of Federal 215s was the largest in diameter--but Federal 210 and 215 Match primers were on the small end of the diameter-spread. Only had one kind of Federal Small Rifle primer was measured, the 205 Match--which ranked the second-smallest in diameter of the 10 primers. That info was published (along with a bunch of other info about modern rifle primers) in Chapter 3 of the first BIG BOOK OF GUN GACK.

I suspect the truth is that ALL primers vary somewhat in diameter, depending on the lot, due to the wear-use of the cup-forming dies.

Seeing how primer pocket uniformer tools are relatively cheap and easy to chuck up in a drill, I would uniform a couple pockets, seat the primers and see how the primed brass chambers.
I would recommend a carbide tool.

I wonder if the center of the bolt face may be a little high, or if the edge firing pin hole has become a bit ragged.

John, that's exactly what I've seen.

Even primers that seem loose don't leak around the circumference due to the cup expanding when the primer goes off. For those wanting to work with primers, uniforming the pockets with a non-adjustable carbide uniformer takes care of 90% of business by standardizing the depth and removing the chamfer around the bottom of the primer pocket. Then, using the uniformer to clean the primer pockets keeps the depth constant.

How much, if any, material comes out of the pocket during load work is a pretty good indicator of things, too.

Good shootin' -Al

I had a batch of military once fired 7.62x51 brass, Lake City, that had shallow primer pockets so it's apparently not a problem that is awfully rare.

I have your book and read the chapter regarding variance in primer sizes.

My basis for this information was a post recently on here that listed specifications for several brands of primers. IIRC its showed federal LR primers at .0005 larger than other brands. Don't know the source for the chart and it could be incorrect.

Dunno--but the first guy I ever ran into who claimed Federal LR primers were larger enough than other LR primers to be useful when primer pockets opened up turned out to have been using a BIG batch of primers he'd bought--which were all from the same manufacturing lot. His comment was one among several that caused me to measure a bunch of primers--which is not an exciting way to spend a couple of days, but I somehow waded through.

Funny story some may find interesting:

One of my favorite 'fun' guns is a Browning B78 heavy round barrel that was originally chambered in 6MM Remington. At some point, it was set back and rechambered to the 6MM Jet....which is based off shortened 307W brass. When f-formed, it becomes what's essentially a shortened 243 Ackley with a rim.

And the 307W cases aren't exactly stout, given the rifles that are chambered in that cartridge. After making these cases and f-forming them, the primer pockets don't hold up real well.

I can push any primer brand I have in with heavy thumb pressure. Yet they've never leaked, despite all the cases having been fired 30+ times. I do a final seat with with a Lee Auto Prime tool to compress the anvil enough for consistent ignition.

Too funny! -Al

Al,

Good example!

Have done some similar things--but the late Dave Gentry contended that Instant Glue worked wonders with keeping fired primers in "over-size" primer pockets. He laughed a little when he said it--but don't think he was joking!

My first experiences with salvaging primer pockets that were deemed "...too loose" by several of my early mentors were with Norma cases for my 220 Swift. At that point, the Swift had been mostly ignored by WW and RP for brass and Norma was all there was available. And while the runout and overall dimensional quality was great, they would rattle the primer pockets loose by the second or third firing.

The first thing I tried was not uniforming the pockets before firing them the first time....letting the pockets 'settle', for lack of a better term. That gave me another 2-3 firings before they got loose. That's a practice I still do today, even with the excellent Lapua cases.

In the end, since they never leaked and dinged up the bolt face, I just quit worrying about it.

I still have a couple of Hart primer pocket tightening tools in a drawer of my tool box.

Good shootin' -Al

I bought about 60 once fired factory Nosler 7-08 brass here on the classifieds. Sized and trimmed it up. Went to prime them and I couldn’t seat primers flush without denting or flattening them.

I got the K&M large rifle uniformer. Chucked it in my drill and made quick work of uniforming all of them. I have 5 firings on some of them and the primers still seat nice and snug and have the same feel when seating them as they did the the first time I primed them after uniforming them.

One of the best reloading tools I’ve bought in a long time.

I bought a 100 pieces of Norma 22-250 brass for a match. At the time, Lapua did not make 22-250 brass. I had to ream every one of those pockets as they were not deep enough.

As to primer sizes. I have 3 lots of Remington 9½ primers. They all measure smaller in diameter than any other primer I've used. Very noticeable when seating. I just figured they were all that way

I have a couple of lots of tall 9 1/2 primers. I have to cut the pockets to the full 0.132" depth to seat them properly.

If a green handloader got some of these along with some shallow pocket brass there would surely be problems.