Converting 7.35 berdan primed brass to boxer

[rovin32]

Hi,
I have a quantity of 7.35 berdan primed cases that I was interested in reloading for. The berdan primers in the cases measured .204 inches. The new boxer primers (no. 200 CCI) measure .2105 inches. This is what I did.
I held the case one at a time in a machinist vise and using a drill press drilled a .070 diameter hole (#50) through the old primer using the firing pin indentation as a guide. This effectively removes most of the anvil. Take your time and be carefull to drill the holes accurately.
Then one at a time using a .187 diameter drill, gently and using an even pressure drilll into the old primer using the .070 hole as a guide just past the cutting angle on the tip and lift the handle on the quill and nine out of ten times the old primer will be attached to the drill bit. Remove it and move on to the next one being carefull not to drill too deep. When all are done move on to the next step.
Enlarge the primer pocket using a .209 diameter drill (#4) just deep enough to go past the cutting angle on the drill tip. Do each one, one at a time until complete. This step will serve as a guide for the next step.
Using a .209 diameter carbide endmill, mill each case to a depth of .125 or just deep enough to remove any of the anvil not removed from the first step, again being carefull not to go too deep. A .209 diameter drill bit with the tip ground flat can be substituted for the endmill but better results will be had with the endmill.
For the last step use a chamfering bit or a larger drill bit to just provide a small lead in for the new primer.

Information

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[vintage hunter]

I tried this a couple years ago. I found it not worth the effort as the brass was brittle due to age, what didn't develop cracks had primer pocket issues after the 2nd firing. I ended up converting 6.5 brass(less work) but that was before PRVI started making 7.35 brass. Only problem now is finding it.

[oldpaul]

Nicely done. It is not always about cost or convenience, the process is often enjoyable for fiddlers like me. Likely annealing the cases will ease the brittleness somewhat. What are you going to do about the step inside the case neck that the original bullet was seated against? Maybe the 128gr flat based bullets available from Graf & Sons will work as is but if you are going to use heavier (longer) lead or swaged bullets, the ridge may cause a problem. Regards. Tom

[rovin32]

Thanks vintage hunter and old paul,
I may or may not have issues with the primer pockets, time will tell. I still am not sure what I will do about the step in the case, will repost with updates.

[DocAV]

Conversion of 6,5 and 7,35 brass from the Italian .204" Berdan Primer to the stand .210 Large Rifle Boxer Was first published by Geo.C.Nonte in his seminal work on Cartridge Conversions ( Home Guide to Cartridge Conversions, Maj.Geo.C.Nonte, Stackpole Books, 1965).

I have varied it a little, by drilling the New Flash hole from the inside of the case. The dimple of the formation of the anvil serves to centre the drill correctly. The Original flash holes remain, but the final "Milling" of the Pocket with a #4 End Mill ( #4 Drill, with point ground flat, and re-cut to resemble a 2-flute slot cutter) will remove any left over anvil. The Flash Hole drill is mounted on a 1/4 round bar to extend its reach into the case. ( and stiffen it.).

This was in the late1960s, when the original Mil cases weren't so Brittle as they are now ( age cracking).

Since PPU cases became available, and my re-forming .220 Swift cases ( 6,5 Japanese, 6,5 Carcano, 6,5 MS) I don't waste time doing Primer Pocket conversons on cases which will Split, Separate or Blow the Pocket web on the first shot (even if annealed properly.).

As to the Machined Step in the case (6,5mm) for Bullet seating, the only thing is to ream it out.

Anyway, original 6,5 ( and 7,35) cartridges are getting Collectible these days....either loose or in original clips/packets...and the Primers on most are Cactus anyway...

Doc AV

[oldpaul]

Brass doesn't get brittle or crack from age. It can get brittle from working it e.g. shooting and reforming or from exposure to some compounds most commonly ammonia or mercury fulminate but not from just sitting around for multiple decades. If more zinc is added for economic reasons or for some war expediency the resulting brass can be more brittle from the outset. Some time ago I bought some the 1950s era Kynoch 577-450 Martini Henry ammunition that has the deserved reputation for misfires, hangfires, and cracks upon firing. I used the tried and true method of pulling the bullets first, annealing the cases and modifying the primer hole to take a number 209 shot shell primer and am at six reloads and counting with only one split neck. I also have some new old stock Remington 8X50R Lebel brass that are on their 22nd reload at last count with no failures of any kind. In any event I think it is prudent and probably curative to anneal your brass. As you likely noticed, your 7.35mm brass also has the ledge inside at the base of the neck. Although I have never attempted it, I suspect that a drill close to the correct .300" (an 'M' at .295, or a 19/64 at .2969" maybe?) would probably take out enough metal for the neck expander ball to do the rest. Please update pro or con. Regards. Tom

[Aragorn243]

Graf and Sons has a company that is loading 7.35 using ppu brass. I have two boxes of it but I haven't shot any of it yet. It's in or out of stock so you just have to keep checking. I don't throw anything away but I'd be pretty hard pressed to reload berdan primed cases. But good to know how to do it if I ever needed to do it.

[Patrick Chadwick]

I suspect that a drill close to the correct .300" (an 'M' at .295, or a 19/64 at .2969" maybe?) would probably take out enough metal for the neck expander ball to do the rest.

Go metric! 7.6mm = 0.2992". But only in a properly rigid setup. Hand drilling usually runs a bit oversize.