Purpose of over primer card?

[vagrantviking]

I've been looking at some BPCR load data and a number of the loads that shooters are recommending includes a newspaper card over the primer.

Not sure if they mean just in the primer cup or in the case below the paper. I'm just curious if anyone knows the reasoning behind this?

Thanks
VV

 

[ben hunchak]

Alot of savy experimentors are experimenting with lighter primers and/or a thin wad of paper between the powder and the primer(inside the case). The idea is to reduce any chance that some of the powder, bullet, etc. is being moved forward by the primer a millisecond before the big bang. Using the lightest primer or retarding the amount of initial gas produced by the primer is an attempt to keep all in place before the big bang. I won't give my results because alot of great shooters over the years shot some incredible scores that still haven't been beaten, and they didn't use over primer wads. I do however use the lightest primer possible including using large pistol primers under 103grs of Swiss BP in my 50/90 Sharps...Oh and by the way, I don't consider myself one of those "savy experimentors"!!!

 

[Smokepole]

I think it is to tone down the blast of the primer as black ignites so easy. It helps with consistancy from shot to shot.
I tried two methods when I reload my BPCR.
1. newsprint disc Drop in the case before the powder charge. Cut your own with a smaller cartridge casing chucked in a drill press. Cut right thru a stack of paper, then push them out with a wire through the primer hole.
2. Foil placed in between the primer and casing, then prime. The primer cuts the wad. Cut a long strip of foil (I fold mine double for more thickness and then use a pistol primer). Trim and feed the strip before each primer goes in.

 

[vagrantviking]

I was wondering if that was the reasoning. Last time I was doing load development the current wisdom was to use magnum primers which seemed to work OK.

Guess I'll have to try the pistol primers when I find a chance to get some more. Don't have access to a range over 25 yards till April anyway and that one is 2 hours away so load development is slow.

 

[BUSHMAN79]

Use caution if trying pistol primers. The firing pin on most Sniders, for example, can punch right through them. Not good. Prime a few cases and try them without a charge first.