when your fireforming a bottleneck case, how much of the taper can be taken out of the body
before you lose strength in the wall? if the base measures .550 and the base of the shoulder
is .485, what would be a safe maximum you could take the base of the shoulder to?
also, if the shoulder is not supported in the process{ rimmed case} is there any tricks to get
the case perfectly straight in the chamber or does it matter?
thanks
woofer

I don't know the answer to your first question but the best way to insure proper fireforming is to do it with the bullet seated into the lands. This will insure the case head is held firmly against the face of the receiver (or the bolt face if it is a bolt-action)....you need to be careful of the powder charge as seating a bullet into the lands can very, very quickly raise pressure past the point where you want to go. Just how much and type of powder you will need will be cartridge specific.

Follow DB Bill's advice for the beltless cases.

If it is a belted or rimmed case, then the headspace is not a problem of course.

I have fire formed 300 H&H up to 300 Weatherby in both RP and WW cases with nary a problem. About a hundred rounds of each, with no lost cases.

I do not think the jump you are talking about is any problem, but the cases will likely shorten when blown out at the shoulder. Your trimming may be just for uniforming the case mouth, but concentricity should not be a problem if you have a good chamber. Neck turning might be involved for ultimate uniformity, but only necessary for the ultimate accuracy nut, most of the time.

My smith has a reamer for a 30 Cody Express, a full length 30 cal improved 416 Rigby cased wildcat. It has .015" taper. Another guy sent me a formed case from his 338/416 Rigby Imp, it had .025" taper. I would stay at least .015" if not .020" - .025" to offer easy extraction. Other guys here will know what works and what doesn't for sure.

I have been through this on designing reamers, one reamer company got me in trouble, my gunsmith said .008" per inch body taper was max, reamer company said .005" per inch. I went with the reamer co because I thought they would know better than anyone, they were wrong, I had extraction trouble. The maximum taper for reliable extraction is .008" per inch, Tim.

could i then blow out the case from .485 to .540 at the base of the shoulder? seems like a very large jump. i would think the case would split before reaching the chamber wall.
if i could would it affect the life of the case by a considerable margin?
thanks
woofer

The case won't split, remember ALOT of heat is involved in this too. Just make sure you have that .008" per inch, .010" and you'll never see a difference either. What case is it based on?

woofer, you must measure the distance from base to shoulder. Lets use your figure of .550", now the distance to shoulder, to make it easy lets call it 2.0" to shoulder, @ .008" per inch would be a total of .016" so the shoulder diameter should be .534" @ shoulder.

.010" per inch of case then would be a safe rule of thumb.
the case is the 348 winchester. i wewnt through howell's book last night and see that this has been necked up and down for everything but one was a strange one.
they had blown the case out to .530 or something at the shoulder but the shoulder itself was a true radius! no sharp angles! the neck and case body were normal but the shoulder itself was a nice radius that continued the case body to almost a 90% turn at the base of the neck. i thought maybe that this was what they had to do to keep the brass in shape when blowing it out. i will try to find a picture and post it. it was very slick.
i was wondering what type of lever actions could handle a wildcat based on the 348? seems like a nice case with plenty of volume but oal would be rather short for fitting in most actions.
thanks to you all!
woofer

Are you necking up or down while fire-forming or are you just moving the shoulder and removing taper?

You might take a look at the dimensions of the .284 Winchester......in my view that is about the minimum shape for reliable feeding. If you are talking about a single-shot then I don't see a problem as long as you have reliable extraction.

Final note.....working with a wildcat cartridge can be fun but it can also be very expensive(if you need to redo things) frustrating...especially if your 'smith isn't near to work with you and very time consuming. Just a word of advice from someone who's been there.

i would be necking up. i wouldn't move the shoulder, just sharpen the angle a bit with the case being blown out. any idea on actions? win big bore 94 or marlin 1895? i see that this should have the water capacity of the rem 7 mag or close. i dont know what that relates to in powder charge ie pressure and such but the volume will be there.
thanks
doug

Now you got me. I know nothing about lever-actions but there are ton of books out there on wildcats etc.

sorry bout' that. the wildcats in the book mostly had just been necked up or down with few blowing out the case to max capacity. a simple neck up would be easier but why not blow it out. this will take me the rest of the summer to finish so no hurry.
thanks
happy holidays
woofer

What caliber? No reason not to blw it out at all, except that a reamer for an existing cartridge design is rentable and cheaper. You might try to see what's availible first, your smith may have a reamer already too. All things to consider. Lever guns are not my thing but Marlin is my preference.

either 375 or 416. 416 being the preference. i checked with reamer rentals and they only list a 450 based 348 wildcat. not my thing. the reason i am building the lever is i could duplicate this in a bolt with an existsing cartridge or necking up a wsm or 350 mag case. i have a nice 350 so i cant justify building something "different" so close to something i have. and the levers kinda get to me after a while. i like the "handy" carry characteristics they have. open sights and such. this wont be a fancy one by a stretch. it will stay the season at our camp in maine. i am hoping to find an abused big bore or an older 1895 for under $300 at my door. the rest will be a piece at a time. if it gets to much of a pain i might just build that 416 wsm i have wanted. who knows.
woofer
happy holidays!

Mic McPherson, a left-handed lover of lever-action rifles, has built a .416 based on the Winchester .284 using a Model 99 Savage. He says the rotary magazine works great. The ballistics he reports are 2475 fps with a 300gr bullet, 2300 fps with a 350gr bullet and 2150 fps with a 400gr bullet....that get you over 4000 ftlbs of muzzle energy.

He also has done something called a .510 Kodiak Express on a Marlin 1895.....300gr at 2780 fps, 400gr at 2440 fps and 450gr at 2220 fps. I don't what the parent cartridge is but he says you need two mercury reducers in the butt to start. I guess the recoil is substantial.

Mic writes for a lot of the magazines but is most seen in Precision Shooting.

that 510 sounds like a rhino laxative! geez. what a blast that would be to shoot. once.
i like the 416/284 idea but i was trying to do something with a rimmed cartridge if i was going to go with a lever. dont ask me why. i think because i was planning on win or marlin and the rim diameter is where i was starting.
is it roughly the same price for a lever rebarrel as a bolt?
thanks
woofer