European screw in primers - why?

I wondered, and found this quote in this doc

"These and all other European rounds of 20 mm or over use screw-in primers
whils we use the much cheaper press-in type. An interesting sidelight is why
Europeans insist on them. The author once asked a Swiss. He laughed and
said, “Well . . . it seems that as ammunition ages in storage, the first part
to go bad is the propellant. With screw-in primers we can remove the primer,
dump out the old propellant, reload with new propellant and a new primer and
have a new round . … Of course no one ever does it, but that is the reason.’’”

That’s awesome - thanks for sharing!

Keep in mind that the screw-in primers also have the primary charge built into it (often offensive nitro powder and or black powder).
Means these securely kept it where it belonged to and assured a propper ignition as a simple primer is not always doing the job. Also imagine the long types which contain a large primig charge, fixing these without a thread is only the second best solution.
Also threaded primers are easier to handle upon reloading.

I didn’t know they designed the case to be reloaded.

I’ve watched video of 37mm being reloaded and the pressed in flashtubes with pressed in primers were somewhat complicated to do. The Euro-style screwed in, after getting rid of whatever stakes were used to keep it in place, would be a whole lot easier for sure.

A friend with 30x173mm uses a floor jack to press out initiator tubes.

Very few threaded primers are staked and basically none which were meant to be reloaded.
Of course this was more common in the older days than it is today.

The only staked ones I remember right now are Soviet/WAPA types in 30mm, all of which are not to be reloaded.

Owing to fine threads and proper torque.
Does anyone happen to know the thread size/pitch on 20x139?


Plus special glues and today it is basically Loctite everywhere.
Large caliber ones do not necceessarily have such a small pitch. Need to go and look em up.

Primers of 20x139 and 25x137 + some other calibers are M11x1.

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In British service, screw in primers were found to be beneficial for a number of reasons -

Spare primers were provided to units to replace defective primers at the gun position.

With ammunition in storage, primers can be removed and inspected, visually and for function. For example - the minimum blow to fire a British Standard Cap filled A-1 composition has been determined at 13 in. lbs. Should the primers fail inspection for any reason, the Lot can be identified and the ammunition repaired. In most instances this would require only replacing the primer simply by unscrewing the old and screwing in the replacement, there would be no need to resort to breaking down the ammunition or sentencing it.

In British service, it is not just the cases that are refillable, it’s the primers as well.