6.53 Dutch converted Cases question

[Aragorn243]

I bought a 20 round bag of 6.53 rimmed Dutch ammo yesterday at a gun show. Everything looked good at the time, converted 303 cases. On bringing them home and comparing them to existing Dutch rounds the necks on these are set back a bit, maybe a 32nd of an inch. As it is a rimmed case and the rim creates the head space I assume this is not an issue and they will fire form to the correct dimension. Is this correct? Or do I need to pull bullets and fire form them without the additional pressure of the bullet?

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[WarPig1976]

Your good. Even new brass will come in under minimum case length, the neck will be short by like .005. Your rim thickness is a more critical measurement in this case. I forget the numbers exactly but new .303 brass is .064ish and military brass is like .070,, again I can't recall exactly right now but you get the drift.

[vintage hunter]

Or do I need to pull bullets and fire form them without the additional pressure of the bullet?

Pressure is necessary to ''blow out'' the case to match the chamber. No bullet, no pressure. Being a rimmed case you should be ok. If it were rimless and the shoulder is set back as much as you say the result would be misfires and those that did go off would surely show a fair amount of case stretching and head separation.

I forget the numbers exactly but new .303 brass is .064ish and military brass is like .070,, again I can't recall exactly right now but you get the drift.

WarPig, CHS for the .303 Brit is .064 minimum and .074 max. All .303 cases(military and commercial) I've measured have a rim thickness of .060-.062.

[WarPig1976]

That's where the numbers where coming from,,,CHS. I learned the importance of rim thickness when my No1 was splitting cases,,a few thou makes a big difference.

[Aragorn243]

Everything looks good on them except the neck. The case length is the same, same type bullets, same length total cartridge.

Yes, if these were spaced by the neck, I doubt they'd go off.

I got a box of actual military rounds also but I don't plan to shoot those. Just wanted them for display.

I read about a guy fire forming by putting powder in and then some sort of padding rather than a bullet. That's why I asked. I think it was part of the process for making 41 Swiss center fire cartridges.

[Parashooter]

Fireforming without a bullet is a common custom handloading practice. With a fast enough powder (like Bullseye) the lightweight filler and wad provide enough resistance to allow sufficient pressure to expand the case to fit the chamber.

While this is a useful technique for custom case forming, it's entirely unnecessary when firing rimmed cartridges in a normal military arm with acceptable headspace. Note difference in shoulder location of top and next cases in this image - completely normal and harmless with rimmed bottleneck cartridges.

[vintage hunter]

Fireforming without a bullet is a common custom handloading practice

New one on me, but I reckon your never too old to learn.

[WarPig1976]

New one on me,

Me too...

[browningautorifle]

No, I've known about it for years. The way I had in mind is powder first and then corn meal on top. Carefully chamber and fire. The case expands to spec and you size to finish it.

[Aragorn243]

Corn meal is the filler I read about.