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Factory-formed or cylinder brass?

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Have been thinking about creating another mildcat round. It will be an elongated 6.5mm Creedmoor that I call as of this moment, the 6.5mm Croodmeer. It will utilize the .30-06 Springsteen case and be 2.100 inches long-- the same as a 300WSM to make sure it's a short-action round. Neck length will be 1X the bullet diameter. Shoulder angle will be 23 degrees--the same as a .223Rem case. The angle was chosen because there is a neck-turning tool available that has the blade already cut to that angle. I expect I will have to turn the necks because the brass will most likely be kind o' thick right where we find the bottom of the neck on an '06 case. My question is, Should I use cheap & plentiful factory-formed brass? Or should I procure cylinder brass at $0.78 apiece?

23-degree shoulder angle.JPG


 
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I don't remember what the OAL is of a '06 natively, but necking down even a .308 will cause it to grow. I'm fairly sure changing the body taper will also cause it to grow. Whether it does this predictably or consistently is another matter. However you're probably looking at minimum two annealing steps and I don't think you have any good taper and plug dies (if you want I could in theory design them for you), which leads me to tell you just start with .30-06 brass and go from there.
 
OP
nvshooter
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I don't remember what the OAL is of a '06 natively, but necking down even a .308 will cause it to grow. I'm fairly sure changing the body taper will also cause it to grow. Whether it does this predictably or consistently is another matter. However you're probably looking at minimum two annealing steps and I don't think you have any good taper and plug dies, which leads me to tell you just start with .30-06 brass and go from there.
An '06 case is 2.494 inches long; the Lee Precision case-trimming mandrel trims 'em down to 2.487 inches. The Peterson "wildcat tubes" are 0.075 inches longer than my design length, so they'll work. The Peterson tubes' wall thickness is 0.009 inches down to about where the shoulder is on a 6.5mm Creedmoor. Good thinking on their part.

The dies will be custom-designed by Ben Syring at Hornady; Hornady will make the three forming dies and the two-die reloading set-- just as they did for my two previous mildcats. I'll have Ben design for a neck bushing in the resizer, something I did not have done the first time around. The neck tension was too little on the .358-caliber example, and I had to have Lee make a set of neck-only dies. Took a year; I've forgotten the cost.

Dave Manson will make the floating-pilot reamer and headspace gauges-- just as he did for my first two. Lee Precision will make the Factory Crimp Die-- just as they did for my first two. I had a rough cost estimate written-up for these hard parts, but I've lost it. I sort o' remember the dies, reamer and gauges were around $750 or so. Then we will need to buy a rifle with a heavy barrel; I'm thinkin' a barreled Howa M1500 in 6.5 Creed for around $500 and some. Aluminum chassis; another $500-some. Cut the mildcat chamber in the Howa barrel; another $350-some. Muzzle brake and install it; $270-some. It adds up...
 
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