What in the world?

Greetings Moa Hunter,
Not quite. The primer backed out of the case just means that the pressure is not high enough to stretch the cases. I have not noted any leakage with backed out primers. We are only taking of .1 or.2 mm backed out, just enough to feel or see if you look closely. A leaky primer is almost always the result of a loose primer pocket from a far too hot load current or previous. Even with cases that have been expanded beyond further use (not in my loads in case you are asking) the primers showed no leakage. An interesting thing I found when using cases snug from previous loads with reduced loads is that the cases chambered easily after the reduced load was fired. This supports the suggestion that cases used in reduced loads should be kept separate as the case head space may increase slightly at each firing.
Regards Grandpamac.

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Originally Posted by grandpamac

Close Gyp,
What actually happens is that the force of the firing pin hitting the primer and the primer going of shunts the whole case to the front of the chamber. You can often see this with sub loads where the primer is protruding from the back of the case due to the low pressure. As pressure builds the front of the case grips the chamber walls and the case head is forced back over the primer to contact the bolt face. This is the point where the case may separate. If it does then the gas can flow forward until it gets to the shoulder that is still pressed tight into the chamber. The dents we see form at this point. Dents like that can also form with very low pressure loads. And it all happens in microseconds!
Regards Grandpamac.

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Grandpamac, in the case of a bolt with a plunger ejector, would it not be the plunger holding the case forward in the chamber and not the firing pin driving it forward ??

Yes to the plunger holding the case forward but it is captive on the extractor, some wiggle room though. . the belt also stops the pin driving a belted magnum case forward. You don’t size the belt back when you FLS only the shoulder. In a non belted case more room for the case to move forward in the chamber.

Often when you think you see a ring the paper clip trick will not show it until the case is close to splitting. Just Looking at the outside is not enough.

Greetings Moa Hunter and Dicko,
Yes Moa Hunter the plunger will hold the cartridge forward in the chamber on rifles with ejector plungers. However primers back out on my low pressure loads in my scoped .303. This rifle does not have a plunger ejector so the case being forced forward in the chamber is independent of ejector type. Yes Dicko the belt would hold the case to the rear of the chamber if the belt and chamber recess tolerances were tight. Unfortunately they are not held to tight tolerances, especially on cases that have a substantial shoulder. In practice the belt does not help. If the case is sized just enough to chamber another problem can develop. Minimal sizing can leave an unsized portion of the case body just in front of the belt with hot loads and some makes of cases especially with cases fired in another chamber. Even with the die hard down on the shell holder this may not be resized which can lead to hard chambering. Some of the die manufacturers offer a special die just to remove this bulge. A friend with a .308 Norma Mag used a .300 Win Mag die with the case sitting on top of the shell holder to remove the bulge. Unfortunately the belt on bottle neck cases can cause more problems than it solves.
Regards Grandpamac.

+1 the belt is the only negative of the 7mmRM. It's not a big issue though just requires a little care and awareness.

I've really enjoyed moving to 280AI as my 7mm round of choice.

Good article here on belted magnums including comments on headspacing off the shoulder rather than the belt, as I posted earlier.
https://gundigest.com/more/how-to/be...myth-dispelled

Just gotta have those sexy belts.....

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Originally Posted by grandpamac

If the case is sized just enough to chamber another problem can develop. Minimal sizing can leave an unsized portion of the case body just in front of the belt with hot loads and some makes of cases especially with cases fired in another chamber. Even with the die hard down on the shell holder this may not be resized which can lead to hard chambering. Some of the die manufacturers offer a special die just to remove this bulge.

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Grandpamac,

I mostly set my FLS dies up so that a resized case created a very slight pressure on the bolt when it is closed. The idea being it reduces stretch and increases case life. I have never had a case stick in a chamber and i tend to load fairly warm. My experience would be that if your FLS die is set to bump the shoulder back your taking care of the bulge above the base.

When i have repurposed fired brass from military rifles / chambers in my .223, i may screw / work the FLS die further down in the press (bit by bit), until i get case to chamber and be able to just feel a little pressure on the bolt at close. The big O frame press will be camming over at this setup.

I have had cases come apart at the web twice and in both cases it was due to excessive resizing and repeated firings. Modern bolt rifles have way more extraction power than need to pull a stick case out of a clean chamber with a normal "warm" but not over load.

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Originally Posted by Dicko

Grandpamac,

I mostly set my FLS dies up so that a resized case created a very slight pressure on the bolt when it is closed. The idea being it reduces stretch and increases case life. I have never had a case stick in a chamber and i tend to load fairly warm. My experience would be that if your FLS die is set to bump the shoulder back your taking care of the bulge above the base.

When i have repurposed fired brass from military rifles / chambers in my .223, i may screw / work the FLS die further down in the press (bit by bit), until i get case to chamber and be able to just feel a little pressure on the bolt at close. The big O frame press will be camming over at this setup.

I have had cases come apart at the web twice and in both cases it was due to excessive resizing and repeated firings. Modern bolt rifles have way more extraction power than need to pull a stick case out of a clean chamber with a normal "warm" but not over load.

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Greetings Dicko,
I don't doubt your experience in this at all but it does seem to be a problem with some rifles and perhaps some makes of cases. The problem seems to stem from the rather generous chamber tolerances of some rifles and a thinner case head with some manufacturers. I had a ferret around on the inter web and found that the tolerance between minimum case and maximum chamber to the head space datum for the .30-06 is about 0.013 inches. This is about the same as the belt length tolerance. The min cartridge to max chamber tolerance for the 7mm Rem mag is about twice that at about .024 inches. So if the belt is toward minimum and the chamber toward maximum (which seems to be the rule rather than the exception with factory chambers) there can be a significant gap between the front of the belt and its recess in the chamber. If the case also has a thinner head then the body can bulge into the gap. This is what my friend found with his .308 Norma. Innovative technologies in the US offers a fancy collet die that deals with the problem which I imagine they would only do if there was demand.
No doubt a gunsmith could ensure any chamber he was cutting would be close to or at minimum thereby eliminating the problem. I suspect that most do. I have to admit right here that I don't own any belted magnums and have only loaded for one. This was a .350 Rem Mag for my son. I didn't have any problems and I don't think he has since he took over. He calls it his .350 Whopper Stopper. I have read about the problem in Handloader and knew what was going on when my friend had the problem. Perhaps you have been lucky.
Regards Grandpamac.

Grandpamac,

Good dialogue and in the right spirit. I guess my point here is we tend to wear brass out more quickly than needed by over re-sizing it, that is FLS at each re-loading and making cases smaller than they need to be, instead of making just the right size so it fits snug in the chamber. Hence we get stretching and case separation. When norma and lapua brass is getting close to $3 a piece for some calibres, you want to make it last. I see neck size dies making a comeback.

Thanks for that Dicko,
I use neck dies for most of my handloading. For the .303's it is a Lee Loader. Redding bushing die for the SAUM and cartridge specific neck dies for most of the rest. Minimal full length sizing is only when needed. I am not short of brass by any measure but don't see the point of squandering it either. I am still using some brass that I first loaded in late 1979. I made the point about the bulge as although it may not happen often it does happen as my friend found. Perhaps one of the others is struggling with this might find the information useful. My son has gone to using FL bushing dies together with the Redding shell holder sets for his target shooting in his Barnard rifle and gets extended life from his brass. He is another hand loading loony just like me.
Regards Grandpamac.

Ive been partial length resizing since first started rolling my own 25ish years ago....the "how to " and why is in my 1st edition nosler reloading manual.my poohseventy HATES neck sized ammo.....suspect bore is slightly off centre from chamber.... and full length resizing works brass heaps and had led to head seperation early on...so have stuck to partial sizing...when I got the .223 and .308 it got same treatment....the BLR wont chamber brass unless its been full length sized and some of it needs to go through an older 30/06 die aswell to squeaze the base in enough for it to chamber easily....which makes me suspect the hornady new dimension .308 dies have generous chamber sizing.

For my 2 cets. I always like to have the rifle present when I'm doing my case sizing to ensure I do the minimum amount of brass working.
I have 243 lever that requires a full length resize to minimum specs everytime. This also means I have to trim the brass every time. Hence I only get about 5 loads out of my brass. I brought a set of picks to test for that internal crack and do so everytime. You can see that ring on the outsize.
Had a trail boss round separate which stated this.

My bolt 243 and lever 358 only get a neck sizing and I can go 5-6 or more uses before I have to trim.
Z

That couldn’t of happened on fireing unless the dents are in the chamber as rased Portions
The brass will always form to the chamber

Unless something happens during a case head Separation never had one
So wouldn’t know

That couldn’t of happened on fireing unless the dents are in the chamber as rased Portions
The brass will always form to the chamber that being said if there was dents in the case before fireing they should be gone now aswell

The case head separation is really bad is the rifle still in one piece if so id have it checked over by a Confident gunsmith
You could of damaged something pretty easy

The dents are the strangest bit
Unless something happens during a case head Separation never had one
So wouldn’t know

@gundoc @greghud might be able to help out more here

Unless Obviously it’s fireformed forward into the Throat which would be understandable as no case head stopping it from moveing forward