Best trimming option and other questions?

[lurcher]

I'm getting some form dies made to make a simple wildcat based on a 7mm saum case. The dies will allow me to simply push the shoulder back 200 thou reducing the case capacity to about 66 grains, similar to a .284 win or .280.

For FL sizing I plan to remove 200 thou off the bottom of a redding body die (I will neck size with a Lee collet neck die)

I plan to have an existing reamer run in short. The axial clearance at the base of the case based on examining the reamer print and measuring unfired rem brass will be a hair over 2 thou.  Hoepfully enough to avoid the dreaded bolt click at top of the lift?

Had anyone had any experience with running reamers in short and subsequent base sizing issues is 2 thou enough clearance? Has any one tried/had success with polishing a chamber to open up the base dimension a thou or so?


Getting to the trimming question, what would be the easiest way to sort this? trim prior to forming or after? Would I be best to make up some kind of trim die or is there an alternative approach?

[yooper77]

I'm getting some form dies made to make a simple wildcat based on a 7mm saum case. The dies will allow me to simply push the shoulder back 200 thou reducing the case capacity to about 66 grains, similar to a .284 win or .280.

For FL sizing I plan to remove 200 thou off the bottom of a redding body die (I will neck size with a Lee collet neck die)

I plan to have an existing reamer run in short. The axial clearance at the base of the case based on examining the reamer print and measuring unfired rem brass will be a hair over 2 thou.  Hoepfully enough to avoid the dreaded bolt click at top of the lift?

Had anyone had any experience with running reamers in short and subsequent base sizing issues is 2 thou enough clearance? Has any one tried/had success with polishing a chamber to open up the base dimension a thou or so?


Getting to the trimming question, what would be the easiest way to sort this? trim prior to forming or after? Would I be best to make up some kind of trim die or is there an alternative approach?

I have to ask you Why? I don't understand the need for such work. Plus dies are hardened and will be a chore to remove 0.200" off the bottom.
 
yooper77

[jedman]

Lurcher,   If I understand you,  Yes I have ground and polishes a rifle chamber to pick up a few thousands  clearance.
  I built a short rimmed version of a 270 Win. on a 7 X 57 R case by removing about .240 off the bottom of the sizing die and sizing the 7 X 57 R to the new neck and shoulder profile.
Being both the 270 Win and the 7 X57 R have the same base dia. after cutting off the .240 I needed to take a dremel tool grinder and while spinning the die chucked in the lathe at high RPM in the CCW rotation I gently ground the base of the die until I got it back to the dia it was before cutting.
I used a pre chambered 270 Win. barrel and after I had dummy rounds made from the modified die I used them as a headspace guage so when I cut the breech end of the barrel off and made the rim cut I used the dummy rounds to headspace the new round on the shoulder and the rim so as to have a near zero headspace.
The chamber in the barrel then had to be gently ground like the die for clearance.
When done right you cannot see any step or difference in the fired brass, they come out looking just like a factory round.                             Jed

[lurcher]

I have to ask you Why? I don't understand the need for such work. Plus dies are hardened and will be a chore to remove 0.200" off the bottom.

The reason I am doing this is that I have a remington model 7. You cannot fit wyatts extended magazine boxes to a model 7 like a model 700 short action because the trigger is too close to the rear of the magazine slot.

I had a nice barrel chambered with a no turn neck reamer with 180 thou freebore. 160 grain VLD type bullets (160 accubond 162 amax). seated out to the lands are about 160 thou longer than magazine length. If I seat the bullets to magazine length they take up room in the case and with VV N165 powder loads are compressed at close to starting loads. I calculate that in order to have bullets touch the lands and feed out of the magazine I would need a reamer with no freebore. Apparently not a good idea.

I would like to have a lightish carry rifle that can reach out further if needed, I would like to shoot 160 grain VLD bullets. I like to be able to  load bullets that will feed out of the magazine and be within a reasonable distance of the lands (usually I start at 20 thou off when working up loads). I could stick my current barrel on a 700 long action and the problem would be solved. I like my model 7 and I have put some work into it. Fibreglass stock, basix ERV3 trigger gretan bolt kit action trued decent mounts etc... It has a magnum bolt face so without a new bolt I can't switch calibers to anything that will fit the mag. I live in New Zealand so finding a cheap long action with a magnum bolt face is not easy...

Thankyou Jedman I am thinking along similar lines. I have ordered a custom form die plus inserts, go and no go gages from spencertooland grind and a redding trim/form die which I will modify for the trimming. Looking forward to trying the brass forming. Here is a link to a similar form die to the one I am getting

[briannmilewis]

Jedman has more than one wildcat project under his belt, I think he did similar work on our 223 Short project too. He knows what he is doing, good advice, take it.