Berdan Priming

Posted by on November 15, 2011

Berdan priming is really an unneccesary chore, but some of us do it for various reasons.   In my case, I couldn’t bear to throw out 300 good once fired cases, so, as berdan primers are still available (occasionally) in South Africa, I accept the chore of loading them.    

Once primed, the rest of the loading process is no different from boxer.    The chore is in the decapping.   There are two methods of decapping, a hook tool and hydraulics.    The only tool I know of is the RCBS.   It hooks into the rim or extractor groove, and a hardened tooth penetrates the primer and lifts it out of the pocket.   I have found it unreliable.  It works only some of the time, and breaks teeth often.    To be fair to the tool, military primers are crimped into their pockets and are very resistant to removal.  

Hydraulic removal is a bigger chore but works better.   At its simplest, the case is filled with water, and a close fitting steel or brass punch inserted into the neck and struck a smart hammer blow.    The hydraulic pressure is  often, but not always, enough to force out the primer.    It depends on the crimp.    On one occasion, half the primers came out easily enough, but the other half were so tight that the pressure bulged the cases enough to reduce them to scrap.    But that was extreme, and usually they come out without damage to the case.

It is a bit messy, but it is only water.   I do it inside one of those plastic cat litter trays.   It also works better with a base for the case.    I use a decapping base from a Lee Loader.    It is nothing more than a steel cylinder with a through hole and a counterbore for the case head.    The punch must be a tight fit, ie tight enough to need a couple of light taps to get it into the case neck.    If it is not tight, the water will squirt out the neck and the hydraulic pressure will be insufficient.

The first job after decapping is to chamfer the pocket with a chamfer tool.    I do that with my boxer cases because it eases priming, but it also removes the crimp from the berdan cases.    Future hydraulic decapping is then much easier.

I prime with a Lee hand priming tool.   As berdan primers are slightly bigger than boxer, they won’t fit into the shell holder.   I polished out the hole of a shell holder to take the berdan primers, and made a new punch to fit the hole.    Fortunately, it is for the 308 Win, which makes that shell holder fit a whole lot of other calibres. 

I haven’t checked whether press mounted primer arms, or ram prime tools, have enough dimensional tolerance to work with berdan primers, but if not, they shouldn’t be difficult to modify.

Small berdan primers are 4.50mm (0.177″) diameter, boxer are 0.175″(4.445mm).    Large berdan 5.50mm (0.2165″), boxer 0.210″ (5.334mm).    Note also different thickness.    Large rifle berdan 2.76mm (0.109″), boxer 3.22mm (0.127″).    As boxer primers are made to imperial dimensions, nominal thickness is 0.125″ so the measured 0.127 is because of tolerance.    Small boxer primers are 0.302 – 0.304mm thick (0.119 – 0.120″).    I have no small berdan to measure, but it can be assumed that they are thinner than boxer.

Sophisticated tools are available for hydraulic decapping.    They work on the principle of equalising pressure by having water inside and outside the case.    The idea is to avoid losing the cases by bulging them.    A buddy of mine made one – it worked very well.

All this is for bottle necked rifle cases.  It doesn’t work too well for short pistol cases like the 9mm or 45ACP, because the case tapers inside, and there is not enough depth for the punch to exert enough pressure.   It will probably work quite well for longer straight cases like 38 Spl and 357 Mag, but I haven’t tried it.

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  1. Willie barnard November 23, 2011 6:21 pm

    Dear Richard,
    I also dislike discarding anything that has to do with shooting.
    Years ago, I used to reload a lot of PMP berdanprimed cases in the 9 mm Para.
    I scrounged all the “not reloadable” brass on shooting ranges, and reloaded them.
    I started withe the RCBS berdan decapper, but it broke pins all the time, and damaged the anvils if set too deep. Then I got the following idea:
    Needed: Lee loader shellholder (the one you stand the case in when decapping with a mallet) for 9 mm, .270 Win case fired, 7,65 ACP case fired. Hammer.
    Method: (do this outside – it is a wet job)
    Place the 7.65 case over the neck of the .270 case and tap with hammer till it is tight.
    Fill the 9 mm cases with water.
    Place the lee shelholder on an anvil, or sturdy bench.
    Place 9 mm case in shellholder.
    Place bottom of 7,65 case in mouth of 9 mm case, and give a sharp tap on top of .270 case. Remove spent primers from under shell holder every 5 or so cases.
    Let cases dry and reload as usual.
    This way I saved a lot of money, and I never had to be too particular about finding all my doppies on the range, as the supply was allmost endless.

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