Practically all of the 6.5 Dutch ammo was/is Berdan primed.  For practical purposes, you will only get one shot out of it.  Some or all of the bullets will be copper or cupro-nickle plated soft steel. These are a bit tough on the bore, but may be valued for other purposes.  Many of the war-time cases are steel and are of dubious desirability.  When you inventory the stuff, test the cases and bullets with a magnet.  Separate by headstamp and by magnetic/non-magnetic.  Also measure bullet diameters of the various headstamp loads.

There are those who shoot the Dutch or Rumanian military rifles (I am one) and those who shoot long-range target rifles chambered for the Dutch cartridge.  If the brass is good, it may appeal to the target rifle guys.  Otherwise, military shooters are your market.

For a behind-the-seat truck gun, I replaced my Bannerman Krag with an Old Model 1895 Dutch carbine, so I'm a potential buyer.

FWIW:

After WW1, the 6.5X53R cartridge (.256 Mannlicher) had some popularity in Great Britain as a Hunting Cartridge for Deer in Scotland.

After "The Great War for Civilization", long barreled Dutch infantry rifles hit the surplus market. Famous British Arms Makers bought the inexpensive, but, well made rifles, fitted handsome sporting stocks, and installed multi-leaf 'express sights. (The cartridge was simply the rimmed version of the 6.5X54mm Mannlicher-Schoenauer round and shared the rim and head dimensions of the .303 British round). Hunting ammo for the 'Dutch Mannlichers' was loaded in GB.

I use to have a ('Bubba-ed') 6.5mm Dutch Mannlicher carbine. I shot a few score of the brass-cased military cartridges through it and it proved relatively accurate.

Tired of cleaning for corrosive primed ammo, I reloaded for it, using .303 British and .30-40 Krag brass, reformed with 6.5X54mm M-S Dies. This worked well using 6.5X54 M-S loading data.

(I learned a valuable lesson one day!):

I loaded some of my re-formed brass with the 'square-flake' powder and projectiles from Dutch military ammo (I had pulled the bullets on). I poured the full charge from each 'pulled' round into my new re-formed brass.

I 'proof tested' that little carbine!

When I opened the bolt and ejected the first fired case, the spent primer fell out of the stretched primer-pocket!

I was lucky. No harm done except to one re-formed cartridge case. I disassembled the rest of these reloads and used the powder to fertilize our garden.

I would recommend keeping your 6.5 Dutch ammo as a collectable. If you get a Dutch Mannlicher and chose to shoot it, remember the primers in your ammo are corrosive.

(p.s. - The Mannlicher 'clips' are likely in short supply and more valuable than your ammo).

These are the same 6 cases from the previous photos. This should be fairly representative of the finished product after thorough clean up. I've included a shot of the case head showing the sealant still around the primer.

Sorry it took me a little bit to post pics of my pull down. The Artillerie Inrichtingen brass as you can see from my second photo marked their projectiles on the base as well.

Studying the cartridge more I have discovered a change in head stamping circa 1921. Pre 1921 you will see codes at only 12 and 6 o'clock. Post 1921 you will possibly have markings now at roughly 12, 3, 6, and 9 o'clock. Marks at 12 o'clock denote year of manufacture, 6 o'clock indicates brass supplier/manufacture, 3 o'clock is date of manufacture, and 9 o'clock is powder lot. Many of the cases were re used and subsequently over stamped at later dates. This could explain the headstamp with all numbers we were having difficulty Identifying. Re used cases were either over stamped with new numbers, a O, or in some cases a triangle.

No problem at all! I enjoy learning about the history behind weapons, ammunition, and world militaries and sharing with others. This is really the only forum I belong to and I enjoy being able to converse with like minded individuals.

I have cleaned the clips with a nylon brush as well as an all copper penny/bronze brush on surface rust, then soaked in a mix of marvel mystery oil and break free for 3 days, brushed again with nylon, and finally lightly tumbled in some corn cob media. I will be grading these into two categories Grade A (little to zero minor surface putting) and Grade B (will contain surface pitting and have significant loss of the lacquer coating but not impact functionality whatsoever). I will probably post a listing for sale either later today or tomorrow.

I definitely most enjoy the KCA Forum.

There are many other interesting 'gun forums' with talented, generous, and helpful individuals.

Gunboard's Forums is a 'Really Big Tent' with some interesting coverage of more obscure firearm families and good 'search features'. It has a forum on Mannlicher weapons.

I found an interesting link there to the Dutch Army Museum. If you Google Search: collectie van het Legermuseum and select 'thema's' and then 'draagbare wapens', there is interesting information on the Model 1895 rifles and carbines.

I don't speak or read Dutch, but could figure out some things: "Munitie" must mean munitions. The site has some neat graphics and pictures.

Paul, here is a pattern for Dutch "Patroonhouders"!!!