Primers end up proud of the case head in 358 win Mauser 96

[zymguy]

What have I got going on here ???

Primers end up proud of the case head in 358 win in a rebarelled Mauser 96
218583
218584
218585

[Bazoo]

Max headspace or, perhaps over max headspace. I had a winchester 94 that did that.

[bosterr]

Your spent primers look very round suggesting a light load. A light load will allow the primer to back out.

[CastingFool]

Your spent primers look very round suggesting a light load. A light load will allow the primer to back out.

This!

[Pipefitter]

How "hot" are the loads? Factory or handloads?
I had a 30-06 with a slightly long chamber (but still within spec) that with the resizing die touching the shellholder and starting loads, would back the primer out like that.
Take a factory or mid to high range load and fire it. When you go to resize that case lube it and then smoke the neck/shoulder area with a candle. Back the sizing die out a couple turns and size the case. Look at the neck area and you will see where the die is working the brass. Adjust the sizing die into the press until the shoulder is just being touched by the die and lock it down (this will set the "headspace" for the cases in that particular rifle).


What is actually happening here is short case is fed into a long chamber (although both may be "in spec" but at opposite ends of that spec).
Firing pin hits primer, driving case into the chamber before powder starts burning. Pressure from burning powder sets primer back against boltface, increasing pressure causes brass to swell to grip chamber but is insufficient to stretch case back against boltface which would "re-seat" primer flush with case head.

[zymguy]

They were mild reloads 11 grains 700x under a 158 g powder coated boolit

[Bazoo]

Does it do it with full power loads or just the light loads?

[zymguy]

Those are the only rounds I’ve put through it . I’ve shot those rounds in my 760 they did not behave this way

[jcren]

Common problem with light loads in rifles. As stated the firing pin drives the case forward, primer explosion drives primer backward, but low chamber pressure prevents brass from expanding to fill the chamber and reseating the primer. Long chambers will increase the problem. Repeated use of the same brass for light loads will result in shoulder set-back and shorter brass. This is the reason for the old drilling out the flash hole trick. Drilling allows primer pressure to escape into the brass quicker and reduces primer pressure and set-back. Unfortunately, drilled flash holes mixed and loaded full pressure will subject the primer to higher pressure and possibly blown primers. Personally I use only less desirable mil surp for light loads and drill em. Keep the good stuff to spec.

[Larry Gibson]

The headspace of the cartridge is considerably shorter than the chamber headspace. With the CRF M96 the case is probably headspacing on the extractor. Fire forming the cases to the chamber will eliminate the problem. There are ways to do that w/o excessive case stretch at the web. If you want to and don't know how ask......no problem.

[mdi]

Common problem with light loads in rifles. As stated the firing pin drives the case forward, primer explosion drives primer backward, but low chamber pressure prevents brass from expanding to fill the chamber and reseating the primer. Long chambers will increase the problem. Repeated use of the same brass for light loads will result in shoulder set-back and shorter brass. This is the reason for the old drilling out the flash hole trick. Drilling allows primer pressure to escape into the brass quicker and reduces primer pressure and set-back. Unfortunately, drilled flash holes mixed and loaded full pressure will subject the primer to higher pressure and possibly blown primers. Personally I use only less desirable mil surp for light loads and drill em. Keep the good stuff to spec.

^This^. I've experienced this with light, pistol powder loads in a .223 single shot.

[zymguy]

I’m asking ! :)

[Larry Gibson]

Can you seat the bullets out to engage the rifling (leade)?

Do you have and medium burning powders such as RL7, 3031, 4895, etc?

[Tenbender]

Load up one a bit hotter and see what happens ?

[zymguy]

Can you seat the bullets out to engage the rifling (leade)?

Do you have and medium burning powders such as RL7, 3031, 4895, etc?

These were seated a little longer in effort to come closer , I shoot them out of 2 different rifles currently. I was actually thinking I’d seat deeper which would both put me back in the crimp groove and presumably increase pressure, right ?

Yes I’ve all those powders .

[zymguy]

Load up one a bit hotter and see what happens ?
I may go up a grain but I’d like to find a chronograph to shoot through before I get too far off on my own

[higgins]

Find a case or two that will not chamber if your rifle. Instead of screwing the FL die down till it touches the shellholder, Leave it a turn or three off the shell holder and size a case. If the case will not chamber as it should, turn the die about a half turn and try again. Do this until the case just fits your rifle.

I've done this for years with bolt actions since I'm not hunting and don't need to be assured of easy chambering in the field. The instructions that come with dies often cause cases to be oversized, but the instructions are good for beginning reloaders so that their handloads will chamber easily. I've picked up a lot of .30/30 factory load cases over the years of all brands that have protruding primers. Not unusual with lower-pressure cartridges.

[Char-Gar]

They were mild reloads 11 grains 700x under a 158 g powder coated boolit

There is your answer. All this talk about headspace in interesting, but is not you problem. Your loads were to light to drive the case back against the bolt head and reset the primers. Even with rifles with proper headspace, the primers will back out a tad before the rearward thrust of the case reseats them.

Up the loads and the problem will go away.