Found 50 new Kynoch brass. When it arrived, I see it's for Berdan primers. Are there primers available for these or can they be converted to boxer primers? I've never had any experience with Berdan cases.
Thanks

Can't be converted as the holes are too big and also the two flash holes. Well, I guess they can by drilling, filling, and re machining the primer pockets to Boxer. Not worth it.
You can buy Berdan primers but you will need to look for them. There are a few sized that are all close is diameter so be sure you get the correct size. The Berdans I use are .251" diameter. It's a pain to deprive but a two prong tool can be made to de prime. Seating is easy.
Cal

What Cal said.

"If" you could find them the proper Berdan primer is the RWS 6507.
This Gunbroker advert has them....for a price.
https://www.gunbroker.com/item/849814803

There are/were 2 depths of .254" Berdan used by the Brits, you need the deeper ones for the big Nitro Express cases.
The old Kynoch Berdan primers for the Nitro cases were the corrosive No. 40 and the later non-corrosive no. 172
As far as I know there is nobody importing Berdan primers into the States so you would need to find someone with an old stash of them like the ad on Gunbroker above.
Then hazmat shipping and all that hassle.
- Mike

Here's a table with the Berdan primer sizing. I use Berdan primers when reloading my older Kynoch 404 cases. I have a good supply of the Kynoch 81 primers but can buy a variety of Berdan primers here in NZ. The priming arm on my press with the standard large rifle priming punch seats the slightly larger Berdan primers fine. Have never had a misfire and accuracy with cast bullets seems slightly better with the Berdan primer than the LR boxer primers I use for the same load.

Easy enough to punch the spent primers out, I just made up a two diameter pin, one end fits in the collet of a spare 222 Rem decapper stem and the other end fits down one of the case flash holes (off-centre of course). I just put the 404 cases in the case holder with the handle of my reloading press down, case up through the die hole, locate a flash hole with the adapted decapper pin and a tap with a hammer knocks the spent Berdan primer out. No mess like hydraulic decappers and no damage to the built in anvil as the RCBS Berdan primer decapper can do if you are not careful.

With the larger primers for your 450NE case you may have to make up a larger seating punch although if you start the primers carefully, (make sure there is a slight chamfer to the primer pocket mouth), the standard LR punch should suffice.
Berdan primer decapper for 404 cases with spare length of spring steel for making more pins, never had to though.


Berdan primer chart

I have a good supply of 450 3 1/4 and 450-400 3 1/4 as well as original Kynoch projectiles. Easy enough to load for. Just follow the above examples. I find the original Kynoch projectiles print lower than my Woodleighs by a good 4-5 inches at 50 yards.