I'm working on making a wildcat and need to know how much clearance is needed between the cartridge and the chamber.
The web of the cartridge measures .420, the reamer measures .425 is that to much clearance or is it just right for the cartridge to spring back, thanks, Bubba.

When I've had wildcat reamers of my own design cut I simply told them the dimensions of the finished case. Then told them to allow std clearance.

On 1 I did discuss a tight neck and gave them the OD of the brass I was going to use expanded to the new caliber.

That's what i do to Ramrod but i have a reamer already that i think will work, save me some money and time, Bubba.

FYI Example: The European head diameter of the 6.5x55 calls for .477" and most European made brass is close to that. I have personally measured Winchester brass as low as .468".
I've tried to keep my wildcat's head dia.
(reamer) no more than .003" larger than the Full Length forming dies head dia. roger

Thank you bartsche for your reply, ill check out the dies im going to use and see what i find out, thanks again, Bubba

0,005" is a little above what I have been told is "standard", but will work just fine.
I have a 8mm wildcat (necked down and blown out 9,3x62 to copy an pre-ww2 machinegun carteridge) wich is at 0,005"-0,006"-no problems.

bartsche reminded me I did measure the head of the brass I was planning on using. I didn't have them cut to a factory std then add clearance.

Absolutly; one will be suprised if one measures various makes of brass and compares to CIP or SAMMI!

Thanks for all the info, looks like ill have to have a reamer made or have one ground down to get it right, thanks again.